10.6092/issn.1973-9494/7940
St. Peter’s Basilica inside the Royal Palace of Palermo, known as the Palatina Chapel, is one of the most popular medieval monuments in Sicily. Built between 1130 and 1163, it contains interesting wooden framings that represent both bearing and finishing structures.Studies about the Arab-Norman church have often concentrated on the very rich and suggestive decorative mosaic apparatus of walls and floorings, as well as the pictorial cycle of wooden ceilings. Knowledge about the constructive techniques adopted and, in particular, about the realization of the coverings, is very limited: there are wooden floors built at different levels, vaults and wooden ceilings and among these is the portion that covers the main nave, housing the muqarnas decorations.The fortunate coincidence of the restoration building yard made it possible to gain precious knowledge of this extraordinary wooden structure, also through a laser scanning survey of a significant area of the wooden ceiling, performed with a low range device. The collected data adequately represent the geometry and the state of conservation of the ceiling and have been used to develop a spatial and geometrical analysis of the muqarnas and relate it to the structural layout.The survey of the internal and external sides of the covering enabled us to investigate further the materials and constructive techniques employed in this ancient wooden ceiling. At the same time, we were also able to document the original structural system and the completion parts, its conservation status and the interventions and modifications it has undergone through many centuries.
application/pdf
1973-9494
7940
en
Giuseppe Costa
Conservation Science in Cultural Heritage
construction techniques
The Muqarnas Ceiling of the Palatina Chapel in Palermo
Text.Serial.Journal
https://conservation-science.unibo.it/
17
Articles
2018-03-28
2018-03-26
2018-03-28
2019-09-06
65-85
CSCH
Giuseppe Costa
2017
10.6092/issn.1973-9494/7940
65
Dipartimento di Architettura (d’ARCH), Università di Palermo
1973-9494
construction techniques
en
85
Genovese, C. and Valenti, F. (2010). <em>Restauro dei monumenti nella Sicilia del primo Novecento</em>. Edizioni Scientifiche Italiane: Napoli.
The Muqarnas Ceiling of the Palatina Chapel in Palermo
https://conservation-science.unibo.it/article/download/7940/7656
17
T    HE MUQARNAS CEILING OF THE PALATINA CHAPEL IN
     PALERMO

   Giovanni Fatta*, Tiziana Campisi, Mario Li Castri, Giuseppe Costa6
   Dipartimento di Architettura (d’ARCH)
   Università di Palermo, Italy


   Keywords: wooden structures, muqarnas, ceiling




   1. Introduction

    Roger II, the irst Norman king of Sicily, decided to build the Basilica of St.Peter,
better-known as the Palatina Chapel, at the centre of the Royal Palace in Palermo,
Italy, between the Greek and the Pisan Towers on the remains of an earlier church of
Greek rite. The chapel was consecrated in 1140 [1], but was actually completed well
before that date, given that in 1132, it had already been raised to the level of parish
church (during the Norman dominion, the second in the city after the Cathedral as
regards date of foundation). In 1143 the construction site was still operative, as evi-
denced by a mosaic inscription on the drum of the cupola. The Chapel has a Basilica
lay-out and is characterized by mosaic decoration which entirely cover its walls, cupola
and apseν the loor has marble inlays in geometrical patterns, as have the bases of the
wall surfaces. The interior is divided into three naves, with two different arrangements




                                                                                                   CONSERVATION SCIENCE IN CULTURAL HERITAGE
of decorated wooden ceilings over the corresponding spaces beneath: a slightly in-
clined one, with little vaults orthogonal to the longitudinal axis on the two lateral naves
(also called navatine [1] or navatelle [2]), and a muqarnas ceiling, a type of decoration
commonly found in Islamic-period architecture, with a compact arrangement of niches,
convexities, concavities and stalactites. This ceiling, above the Chapel’s central nave,
has a plan measuring approximately 18.84 x 5.60 meters and is richly decorated with
about 750 well-deined small-scale painted igures and scenes, on a variety of themes
ranging from splendid palaces to gardens with palm-trees, from lions to birds, from hu-
man igures to court-life, from beverages to musical instruments and everyday objects.
Leaving aside the exceptional intrinsic artistic value, it is an extraordinary testimony
to what is commonly considered the only known example of a muqarnas decorative
structure made entirely of wood.
    In previous centuries historians and scholars devoted their attention principally to
the extensive mosaics covering the entire walls and the painted ceilings, but much
less so to its construction from the point of view of the carpentry used in assembling
the wooden parts; our aim is to study both the load-bearing structures and other non-
structural parts in order to discover their peculiarities and possible correlations with
coeval architecture. However, the objective dificulty encountered when studying these



* Corresponding author: giovanni.fatta@unipa.it

                                                                                              65
                                                                                                             artefacts has so far limited technical knowledge to a reductive examination of the vis-
                                                                                                             ible parts.
G. Fatta, T. Campisi, M. Li Castri, G. Costa - The muqarnas ceiling of the Palatina Chapel in Palermo




                                                                                                             Figure 1. Internal view and longitudinal cross-section of the Chapel [1].




                                                                                                             Figure 2. 19th century survey showing longitudinal section and intrados plan of the ceiling.



                                                                                                                2. Past interventions on the ceiling

                                                                                                                Due to the complexity of their structure, the wooden ceilings in the Palatina Chapel
                                                                                                             (central nave and navatelle) have been subject to periodic damage and disigurement
                                                                                                             and have subsequently needed countless restoration interventions, the irst dating
                                                                                                             back to the early centuries of its long existence. In 1348, a document [1] described
                                                                                                             the above-mentioned restoration work as supervised by the engineer Ughetto from
                                                                                                             Milan (the successor to a certain Tommaso di Bonaccorso) on the Sala Verde1 and the
                                                                                                             actual Chapel, following damage caused by a ire started by the Catalana faction in the
                                                                                                             Palazzo Reale, during a revolt in the same year.

                                                                                                        66
   The irst reading and interpretation of the Arabic inscriptions on various parts of the
ceiling, from the springer cornice to the decorative thumbs, seem to have been facili-
tated by access to the scaffolding used during on-going restoration in 1798 [2]. These
inscriptions bear witness to a series of consolidation and restoration interventions car-
ried out in 1478, 1482, 1499 and 1553.
   The emergence of institutions responsible for safety measures prompted the requi-
site inspections and repairs to the monument, which marked a long period of interven-
tions with particular attention paid to the wooden structures. The irst documented 1λth
century conservational activity, handled by Francesco Saverio Cavallari, director of
Antiquities of Sicily in 1867, revealed damage to the wooden structures in the central
nave and to the stonework structures beneath.
   In 1884, the Restorations Director, Giuseppe Patricolo, carried out an inspection of
the condition of the structures and discovered that the ceiling of the central nave was
weighed down by a quantity of rubble deriving from the previous building works; he
had it promptly removed and proposed demolishing several odd additions. He added
(1887) that […] we were able to ascertain that on this side rainwater falls freely on the
brick paving immediately above the ancient ceiling, damaging not just, and in an irrep-
arable way, the magniicent tempera paintings [4]. The works planned by Patricolo and
others were urgently carried out in 1891, since they had to be completed [...] before
the arrival in Palermo of the Royal Family on the occasion of the National Exhibition
(held in Palermo in 1891-92), because it would be exceedingly inopportune, during this
happy event, to present shored up walls […]. In spite of the work carried out, in a report
compiled by the Royal Family’s engineer Nicolò Mineo, damage to the decorated ceil-
ing of the left navatina was detected, caused by the iniltration of rainwater from the
roof […]; apart from this, the entire rooing had aged and was deemed to be in poor
static condition and […] because of the construction system which was unsuitable for
protecting treasures of such importance and rarity. In 18λ3 the old rooing was repaired
and refurbished; iron structures were added together with skylights made with a galva-




                                                                                                  CONSERVATION SCIENCE IN CULTURAL HERITAGE
nized iron framework, at the level of the southern navatina.




Figure 3. Global view of the wooden muqarnas ceiling.



                                                                                             67
                                                                                                                 We need to leap forward to the 1λ20s to ind further information regarding inter-
                                                                                                             ventions on the roof. Francesco Valenti, in 1925, consolidated the structures which
                                                                                                             had to support the ceiling of the main nave from above, inserting squared pitch pine
                                                                                                             beams as additional purlins; restoration work was also carried out on the decorative
                                                                                                             paintings on the intrados together with the consolidation of small wooden parts of
                                                                                                             the ceiling.
                                                                                                                 In 1948, the Istituto Centrale del Restauro, with its director Cesare Brandi, opened
                                                                                                             a building-site employing the Institute’s students. Work was protracted until 1953 and
                                                                                                             aimed to tackle all the problems of the ceiling in the Palatina, with particular attention
G. Fatta, T. Campisi, M. Li Castri, G. Costa - The muqarnas ceiling of the Palatina Chapel in Palermo




                                                                                                             given to the decorated surfaces and gaps in the painted parts. We know that several
                                                                                                             interventions were carried out on the wooden structure.
                                                                                                                 Photographic evidence preceding the restoration reveals the disastrous condition of
                                                                                                             the surfaces with widespread gaps, laking, cracks and blistering of the pictorial ilm.
                                                                                                             The broken-up surfaces were restored and the gaps touched up using water-colouring
                                                                                                             applied with the technique of “colour breakdown” (rigatino), ine-tuned by Brandi and
                                                                                                             subsequently widely used in many interventions of pictorial restoration.
                                                                                                                 After the disasters of the Second World War, the Palatina Chapel, according to
                                                                                                             Brandi, was […] saved by a miracle, in spite of the devastating bombardment of Paler-
                                                                                                             mo […] the ceiling required minimal restoration […]: then one could see the under-
                                                                                                             stated diligence and frail simplicity with which all those cupolettas had been ixed to
                                                                                                             the ceiling […]. According to Brandi, the complex wooden scaffolding supporting the
                                                                                                             ceiling, seen from above, looked like a puppet theatre [10].
                                                                                                                 There was another long wait until the end of the1980s in order to resolve problems
                                                                                                             deriving from the iniltration of water. This was accomplished by the Superintendency
                                                                                                             of Palermo which had all the rooing structures removed and a new roof installed using
                                                                                                             classic truss-beams of glulam with overlapping translucent polycarbonate sheets; at
                                                                                                             the time this was considered a provisional measure.
                                                                                                                 The 2002 earthquake caused extensive damage to the Royal Palace and the Pa-
                                                                                                             latina Chapel; working in synergy, technicians from the Superintendency for Cultural
                                                                                                             and Environmental Heritage and the Regional Centre for Design and Restoration
                                                                                                             were forced to make the irst urgent interventions. The willingness of the German
                                                                                                             industrialist/sponsor Reinhold Würth,2 founder of the homonymous multinational
                                                                                                             tool-making enterprise, to inance large-scale restoration work on the Chapel proved
                                                                                                             providential. A restoration project was inanced with a speciic convention stipulated
                                                                                                             in June 2003 and developed by the two Regional institutions. The building-site was
                                                                                                             opened in March 2005 and the completed work was represented to the city in July
                                                                                                             2008.3 The work-site consented the utilization of a large, stable working-platform
                                                                                                             reaching up to the level of the ceiling intrados. In the irst stages this proved extreme-
                                                                                                             ly useful for acquiring irst-hand knowledge and analysing the plastic and pictorial
                                                                                                             decorative elements, together with sporadic information about the original construc-
                                                                                                             tion techniques and the stratiication of the interventions over the years. Without the
                                                                                                             need to remove the precious painted panels, we were provided with the opportunity
                                                                                                             to accede to the supporting structures, to the lofts and interspaces, in order to in-
                                                                                                             spect and examine the extradoses and the actual wooden structures. The straight-
                                                                                                             forward climb to the platform also allowed numerous scholars and tourists to gain
                                                                                                             access, providing them, for any number of reasons, with the possibility of inspecting
                                                                                                             both the decorated intrados of the wooden structure and the spectacular wall-mosaic
                                                                                                             decoration at close quarters.


                                                                                                        68
   These fortunate circumstances enable us today to have access to wide-ranging
documentation regarding the original and complex carpentry work and the interven-
tions it has undergone [3].
   An opening in the northern wall allows access to the interspace between the roof
slab and the monumental ceiling4 [4]. This circumstance enabled us to carry out ex-
tensive, direct scrutiny of the extrados of this ceiling and to understand the rationale
behind its construction and structure.


   3. The structural/static system of the wooden muqarnas ceiling

    In the inal years of the 1λth century F. S. Cavallari stated that the ceiling was
self-supporting [1], an unshakable conviction which is conirmed by literature in our
possession, according to which the complex system of the ceiling had borne its
weight for about seven centuries. This was evidently before the wooden tie-beams,
which transferred most of the weight to the overlying beams above, had been con-
structed. It is widely believed that, this profound modiication in the static condition
was probably the result of having raised the perimeter walls of the central nave at
the end of the 19th century. Resting on these walls, the afore-mentioned beams
had vertical boards nailed to them and were connected to elements projecting from
the ceiling structure. However, due to their particular design, we think that some of
these boards and connecting rivets might be ascribable to much older consolidation
operations which only analytical studies of the materials and/or archival research
might eventually conirm.
    Through close observation of the constituent elements visible on the bare jagged
extrados, when compared with the highly elaborate shape of the painted intrados (re-
cently subjected to an instrumental survey), we hypothesized what might have been
the ceiling’s original static system, with the exception of the two opposite extremities. In




                                                                                                    CONSERVATION SCIENCE IN CULTURAL HERITAGE
spite of great inaccuracies, the detailed surveys carried out during previous restoration
work (from the mid-19th century onwards), together with the technical-static considera-
tions, proved rather useful, enabling us to formulate suficiently plausible hypotheses
as regards the parts of the wooden structure that remain hidden from view and are
impossible to analyse.
    Taking into account any possible misinterpretation on our part, several rather un-
stable parts were identiied. It is probably these parts which led to the addition of the
afore-mentioned nailed wooden suspending boards This might have been due to the
appearance of deforming phenomena, if not actual structural failure, of which we have
not found any evidence in the speciic literature.
    In order to ind the original static design we deemed it useful, irst of all, to separate
the ceiling structure into two clearly distinct parts: A) the central part which is more or
less horizontal and B) the steeply sloping lateral strips which transfer the vertical load
to the perimetral walls.
    The central part of the ceiling is wide and lat with nine parallel “ribs” approximately
2.5 linear metres long, with a distance of about 1.6 linear metres between the axes,
made up of square beams about 20 cm high and about 8 cm thick. There is a distance
between the rib ends and the longitudinal walls of about 1.6 linear metres. These are
the main load-bearing beams, since their ends are connected to the perimetric system
B by two horizontally extradosed wooden panels, lying in a direction deviating by 45°


                                                                                               69
                                                                                                             from the axis of the ribs and connected to the latter by nailed boards. The whole, com-
                                                                                                             posed of the beams and the extradoses of the afore-mentioned panels, forms the lat
                                                                                                             sub-horizontal part of the ceiling of the main nave.
G. Fatta, T. Campisi, M. Li Castri, G. Costa - The muqarnas ceiling of the Palatina Chapel in Palermo




                                                                                                             Figure 4. A detailed view (from above) of part of the extrados ceiling: central ribs and diagonal
                                                                                                             beams positioned at 45° for reinforcement (brown); central squares aligned symmetrically
                                                                                                             along the axis (red); removable (covering) octagonal cupolas with multilobed star pattern (pink);
                                                                                                             cupolettas on square support (yellow); steeply inclined perimetral strips, with niches, stalactites,
                                                                                                             fan shaped vaults (light blue); perimetral masonry (green).



                                                                                                                 B) Interpretation of the static system of the perimetral parts of the ceiling is much
                                                                                                             more complex. On average the sections are between 65 cm and 90 cm wide in a hori-
                                                                                                             zontal projection, but are actually almost 2.3 m high, bearing in mind the difference
                                                                                                             in height between the central plane and the wide strip linking it to the outer wall. The
                                                                                                             tortuous structural lay-out seems to follow a line that forks out and breaks up in at least
                                                                                                             three points in order to enable the creation of decorative areas in accordance with
                                                                                                             complex and original outlines, and to form the three-dimensional shape of the cupo-
                                                                                                             las, niches, projections and stalactites. In our interpretation therefore, the load-bearing
                                                                                                             structure of each “module” in these lateral B areas, extends in the three directions, de-
                                                                                                             termining geometric igures able to transfer, at several points in an outward spreading
                                                                                                             direction, the load on to a complex and atypical supporting structure which rests on the
                                                                                                             lateral walls. This part is not visible since it is covered by a perimetral boardwalk; it is
                                                                                                             clear however, that the wide band running alongside the springer of the whole ceiling
                                                                                                             does not have the function of load-bearing as might seem evident at irst glanceν it is a
                                                                                                             simple cove composed of long thin wooden boards, decorated externally, their position
                                                                                                             and shape maintained by means of wooden frames hidden at the back [5].
                                                                                                                 As we have seen, whilst it was possible to utilize straight square beams for the ribs
                                                                                                             and some of the connections between them, they could not be used for the steeply-in-
                                                                                                             clined lateral bands in a broken-up axis; here, the load-bearing structure itself is made
                                                                                                             up of lat box-shaped panels formed by pairs of planks arranged in a vertical position,


                                                                                                        70
connected by systems of illets, wedges and joist-spacers at variable levels, nailed
into the space between the planks, their total thickness varying between 7 cm and 10
cm. The structure is very light but at the same time stiff, the lower edges of the boards
shaped in such a way as to follow the complex shape of the decorated intrados. On the
extrados these original structures have been left uninished and are visible from above.
    We believe that this undoubtedly bold and original construction system was chosen
following a series of considerations that offered more advantages than other solutions:
    a) taking into account the spaces between the two layers of boards, one can esti-
mate that the total weight was reduced by over 70% compared to any structure made
entirely of solid wood;
    b) over the course of time solid wood is subject to permanent deformation to a much
greater extent than a system composed of illets and boardsν
    c) making connections along the edges between diversely-oriented planes was
made easier by the use of vertical illets of variable shape.




                                                                                                     CONSERVATION SCIENCE IN CULTURAL HERITAGE




Figure 5. a) Detail of “B” construction system, consisting of wooden planks forming slim box-
shaped panels joined to the central rib; b) extradosal view showing the ribs, diagonal beams,
octagonal cupolas with multilobed star pattern and wooden suspending boards.

   The afore-mentioned perimetric walkway provided by the planking, less than 30
cm wide, (probably) separate from the lower structure, was built at the end of the 20th
century in the interspace between the extrados and the lateral walls. Although this
walkway, on the one hand, made it easier to gain access to the hidden parts, on the
other, it constituted an obstacle to examination of the extrados in the portion beneath
the planking. Therefore, our hypothesis regarding the connection between the load-


                                                                                                71
                                                                                                             bearing structures of the ceiling and the outer walls had to be based on an analysis of
                                                                                                             the overlying structural parts that were still visible and the evidence found along the
                                                                                                             painted intrados surface.
                                                                                                                 In our opinion, assumptions previously put forward by other scholars [5] with re-
                                                                                                             gard to the original support system for the ceiling and connection with the lateral walls
                                                                                                             found partial corroboration during the frequent site inspections in those points where
                                                                                                             they were discovered to be compatible with the geometry of the lower registers of the
                                                                                                             ceiling’s decorative system. Approximately at the height of the irst decorative register
                                                                                                             and thus, well above the cornice at the base, there are wooden brackets crossing over
G. Fatta, T. Campisi, M. Li Castri, G. Costa - The muqarnas ceiling of the Palatina Chapel in Palermo




                                                                                                             the perimetric walls, the rear ends of which are occasionally visible on the exterior of
                                                                                                             the walls themselves. These brackets are no longer visible throughout their length,
                                                                                                             but certain considerations and bibliographical documentation [5] [13] seem to make
                                                                                                             it clear that they jut out from the interior by about 30 cm - 35 cm and support a line
                                                                                                             of beams parallel to the wall, thus forming the main structural support system for the
                                                                                                             whole wooden ceiling. During restoration work in 1928, Francesco Valenti reported that
                                                                                                             there were 11 brackets on each of the long sides (and probably 2 on the short sides),
                                                                                                             with a cross-section of 0.08 x 0.10 meters, resting on a dividing system represented by
                                                                                                             “wooden girders” (with an average cross-section of 0.12 x 0.20 meters) deeply embed-
                                                                                                             ded in the walls. Over a period of time these beams rotted, leading to partial structural
                                                                                                             failure in the support of part of the ceiling, which made it necessary to ill the gaps with
                                                                                                             masonry [13].
                                                                                                                 A box-shaped panel is nailed to the vertical plane which is marked by the external
                                                                                                             ends of the beams and brackets; the panel is made up of vertical double planking
                                                                                                             connected and separated by large spacers measuring 80cm/90 cm in height and runs
                                                                                                             along the entire perimeter. This internally hollow panel with a total thickness of about
                                                                                                             12 cm constitutes the terminal wall of the whole ceiling structure. It receives all the
                                                                                                             loads through pairs of box-shaped vertical panels, rotated through 45°; the latter con-
                                                                                                             stitute the “ramiied” extremity of the afore-mentioned B system, making the whole a
                                                                                                             light-weight structure of great stiffness. This “terminal” panel is joined to the bracket-
                                                                                                             beam system at an intermediate position along its height, continuing downward in
                                                                                                             such a way as to form the irst underlying decorative register and linking up to the base
                                                                                                             cornice which, as already mentioned, consists of a hollow wooden cove.
                                                                                                                 This series of lateral structures (B), with only their lower ends resting on the cor-
                                                                                                             nice which juts out about 30 cm from the wall, is unstable if seen separately from the
                                                                                                             rest of the structure. On the contrary, these lateral structures are to be considered
                                                                                                             fully able to support themselves and any working loads tightly connected to the hori-
                                                                                                             zontal beams (the afore-mentioned “ribs”), by positioning pairs of the same nailed
                                                                                                             planks, that constitute a fundamental part of the structure, along the greater part of
                                                                                                             the lateral surfaces.
                                                                                                                 The sequence of the 9 main transversal trusses described above (A + B), is in-
                                                                                                             tegrated with longitudinal and diagonal linking elements, with a random and vari-
                                                                                                             able use of wooden beams, joists, simple/coupled/multiple planks, illets and various
                                                                                                             types of connecting elements. The result is a three-dimensional structural whole that
                                                                                                             is suficiently stiff with hardly any thrusting force. At the same time the empty areas
                                                                                                             are delineated using geometry suited to receiving and supporting the typical decora-
                                                                                                             tive elements of the muqarnas: from the star-shaped octagons, to the squares with
                                                                                                             cupolettas, from the niches to the stalactites or other built-in or protruding compo-
                                                                                                             nents (Figure 6).


                                                                                                        72
                                                                                                         CONSERVATION SCIENCE IN CULTURAL HERITAGE




Figure 6. View of structural/static system of the wooden muqarnas ceiling - extrados and intrados
view.

   As regards the type of wood used in building the ceiling, speciic analysis carried
out by a team coordinated by researchers from the University of Tuscia identiied the
widespread presence of ir and pine in both the structural elements and the larger-sized
panels, and birch, poplar and beech in the thinner slats. Literature regarding the techni-
cal-analytical study of vegetation existing in 12th century Sicily is limited and there was,
therefore, an objective dificulty in distinguishing between the various species of ir used


                                                                                                    73
                                                                                                             in the construction of the ceiling. Nevertheless, owing to certain peculiar aspects, an
                                                                                                             interesting hypothesis was put forward suggesting that 35 of the 150 samples of wood
                                                                                                             analysed could be attributed to the species Nebrodi ir (Abies Nebrodensis), of which
                                                                                                             only a few examples still exist in the mountains around Palermo; these are acknowl-
                                                                                                             edged as descending from an ancient group that survived the last Ice Age.
                                                                                                                In its present state, in many areas, the central ceiling hangs from the beams above
                                                                                                             by means of small, variously shaped wooden boards that have been nailed in position
                                                                                                             over the years/centuries using rustic wood, thick square planks and metal section bars.
                                                                                                             These have contributed to this unique work being handed down to us in almost perfect
G. Fatta, T. Campisi, M. Li Castri, G. Costa - The muqarnas ceiling of the Palatina Chapel in Palermo




                                                                                                             condition, the lower surface maintaining the extraordinary decorative quality that the
                                                                                                             Medieval artists succeeded in creating. The simple addition of wooden hanging units
                                                                                                             also enables us to perceive, in the extradosal details, the original construction tech-
                                                                                                             niques used in the Middle Ages to support and shape the various parts of a ceiling of
                                                                                                             great complexity and execution, as well as artistic quality.


                                                                                                               4. The ceiling’s decorative modules

                                                                                                                 Observing the ceiling from the rustic and bare extrados, a complex frame is visible
                                                                                                             which, on analysis, immediately reveals the skill used in creating the extraordinary
                                                                                                             tableau of the intrados with simple raw materials; its execution and static reliability
                                                                                                             were the result of construction know-how that was well-known to categories of special-
                                                                                                             ized craftsmen, from the choice of materials in the various applications to the way the
                                                                                                             structural elements were linked to each other, in other words the work involved in the
                                                                                                             inishing and completion stages.
                                                                                                                 The previously mentioned Saverio Cavallari was able to examine the extrados and
                                                                                                             tried to provide an analytical description: […] the vault is made up of pieces of wood,
                                                                                                             whose thickness is no more than about a centimetre and a half, with the ribs and the
                                                                                                             largest sectors skilfully connected to each other and reinforced with bronze pins. How-
                                                                                                             ever, independently of these pins, since the vault is generated from a mixtilinear curve,
                                                                                                             it supports itself by means of the wedge arrangement, in which the ribs are arranged
                                                                                                             between the joints in such a way as to increase the contact surfaces to achieve greater
                                                                                                             solidity. At the point the curve begins there is a series of niches one upon another,
                                                                                                             thrusting upward in order to support the central part where the octagonal lacunars
                                                                                                             are found. The upturned pyramids like so many stalactites also serve as just as many
                                                                                                             wedges … […] [1].
                                                                                                                 As a connection and an integral part of the main load-bearing structure, there is
                                                                                                             a framework that completes the whole by connecting and integrating it into the main
                                                                                                             load-bearing structure, thus giving shape to the lacunars and providing a space for the
                                                                                                             other decorative elements. The framework is made by means of juxtaposing and nail-
                                                                                                             ing planks and slats to give shape to the different surfaces of the wooden muqarnas
                                                                                                             decoration. Planks of wood are linked to small wooden boards and thin wooden illets,
                                                                                                             varying in width, length and section, ranging in shape from rectangle to wedge, use-
                                                                                                             ful for shaping the mixtilinear proiles, i.e. for determining the appropriate curvature
                                                                                                             to be used in the concave and convex parts, in the small-scaled barrel vaults or the
                                                                                                             truncated-cone and/or fan-shaped portions.
                                                                                                                 The wooden elements in the ceiling of the Palatina Chapel have been surveyed
                                                                                                             many times over the centuries5 [6], with results that have not always been consis-


                                                                                                        74
tent. Thanks to the raised work-platform and the site scaffolding it was possible to
carry out a detailed operation of measuring and examination of the ceiling, with the
additional aid of laser-scanner technology, both during and following the restoration
work [7].
    The irst evaluation phases were geared towards individuating the dimensions of
the ceiling and any possible warping phenomena (with regard to both the supporting
wall structures and the actual ceiling); investigations were carried out on the vertical
sections utilizing the cross sections for the axes of longitudinal and transversal sym-
metry. After close examination of the plan, it emerged that the central part of the wall on
the north side is affected by noticeable warping, whilst the east and west walls maintain
an almost straight proile. The south wall presents a planimetric curve on the west side
and a concavity on the east side [7].
    The geometric areas deined by the elements of the ceiling structure provide the
seat for the decorative modules, their succession and juxtaposition creating the volu-
metric shape of the entire ceiling.
    In the lat part of the ceiling it is possible to distinguish the following primary orna-
mental components of the intrados:
    a) 9 squares along the axis of longitudinal symmetry;
    b) 20 star-shaped, multi-lobed octagonal cupolas, arranged symmetrically with re-
gard to the longitudinal axis in two rows, each of ten stars;
    c) 24 circular, low-proile cupolettas along the four sides of the ceiling perimeter;
    d) 56 whole “stalactites”, of which 36 are arranged in groups of four around the
decorative modules of the 9 central squares; the other 20 are distributed along the
internal edges of the modules containing the multi-lobed octagonal stars. In addition,
48 other stalactites, incomplete as regards volume, are arranged along the perimeter
of the lat part of the ceiling.
    εore speciicallyμ
    a) At the intersection between the aforesaid nine ribs and the connecting beams




                                                                                                    CONSERVATION SCIENCE IN CULTURAL HERITAGE
along the axis of longitudinal symmetry, the nine squares with a lat intrados reappear
once again. From above, only the structural elements, at the edges of the square
which deine the perimetric framework are visibleν the two surfaces of the framework
itself are covered by nailed-down planks. At the centre of the intrados surface, richly
decorated with geometrical motifs, there is a metallic ring connected to a pin provided
with an eye which was presumably used as a hook for a lighting holder and anchored
deeply to the rib structure. The vertical surfaces of the stalactites converge at a point
corresponding to the vertices of the square.
    b) The star-shaped, multi-lobed octagonal module on the extrados is a rustic struc-
ture, created and decorated separately and easily removable whenever inspection
of the interspace is required. The posthumous construction of the “hanging units” in
most cases prevents their removal. Each side of the octagons measures about 60 cm,
with slightly variable measurements however, from one lacunar to another; the “star-
shaped” cupola has a rise of about 25 cm.
    The lat part along the perimeter, which is itself octagonal in shape, consists of
boards placed side by side and nailed to at least two other boards positioned in a
transversal direction. To ensure the sealing and consolidation of the joins between
the boards, wood-ibre bast was pasted on in a longitudinal and transversal direction.
    The structure of the poly-lobed star adheres to the building strategy of wooden
ceilings, with centrings of curved ribs opportunely shaped to follow the curvature of


                                                                                               75
                                                                                                             the intrados. These curved ribs are arranged radially and ixed with large nails to the
                                                                                                             planks on the edges of the cover-panel.
                                                                                                                 The “petal” structure is made with curved veneers (probably either using steam or
                                                                                                             through repeated soaking) and lint wood with glue nailed to the intrados of each of
                                                                                                             the afore-mentioned centrings. The cover-panel rests on the illets or the planks at
                                                                                                             the edge which are nailed to the “ribs” and the secondary connecting structural ele-
                                                                                                             ments. On the intrados, the cover-panel bears pictorial decoration only on the part
                                                                                                             that is visible (mostly geometric motifs and human igures). The line of discontinuity
                                                                                                             between the ixed and the mobile parts is partially hidden by small protruding cornices
G. Fatta, T. Campisi, M. Li Castri, G. Costa - The muqarnas ceiling of the Palatina Chapel in Palermo




                                                                                                             that form a continuous cordon, whilst the spaces between the planks and veneers and
                                                                                                             between the supporting structures and petals are hidden by layers of gypsum plaster
                                                                                                             and stucco.
                                                                                                                 c) The little cupolettas, with pictorial decoration of a mainly geometric and non-
                                                                                                             igurative type, are set in the middle of a lat cover-panel on a square baseν this too
                                                                                                             was made with planks placed side by side and nailed on to other transversal planks.
                                                                                                             The cupolettas have a base measuring about 50 cm per side and a rise of about 20
                                                                                                             cm. At the vertices of the quadrangular hole, on which the cover-panel with the cupo-
                                                                                                             letta rests, there are diagonal illets hidden on the intrados that provide a triangular
                                                                                                             support for the vertices of the cover. Only the central part of this decorative module,
                                                                                                             corresponding to the cupoletta and to the perimetric 8-pointed decorative band, was
                                                                                                             built off-site. After being completed and inished, it was placed on the ixed part of
                                                                                                             the perimeter characterized by a star-shaped hole. The cupoletta structure presents
                                                                                                             several construction variables: some have ribs jutting out from the extrados and the
                                                                                                             dome shape, produced using steam and/or wet curved veneers nailed to the actual
                                                                                                             ribs of the intrados, then stiffened with strips of pasted-on lint wood. Others include
                                                                                                             a structure with wooden strips positioned in different directions or a structure with a
                                                                                                             device consisting of small veneer rectangles applied in several layers with staggered
                                                                                                             joints, which perhaps made it easier to obtain the desired curvature. Along the edges
                                                                                                             of the lacunars, created to accommodate the mobile ornamental modules, the rustic
                                                                                                             planks were left to jut out from the extrados so as to keep the cover-panels irmly
                                                                                                             in place, preventing the lateral portions with no decoration from remaining exposed
                                                                                                             (Figure 7).
                                                                                                                 d) The “stalactites” in the central area of the ceiling placed at irregular heights, rang-
                                                                                                             ing between 40cm - 55 cm, are hollow wooden structures, most probably formed by a
                                                                                                             illet frame to which the small lateral wooden boards are nailed. They have the shape
                                                                                                             of an asymmetrical triangular section so as to render the surfaces congruent with the
                                                                                                             adjacent decorative panels. They stand upright, in a position corresponding to the
                                                                                                             central square panels and are inclined and mixtilinear in the other directions. As with
                                                                                                             the cupolettas they were constructed separately and then nailed to the structure above
                                                                                                             with appropriate boards and illets which emerge from the extrados of the stalactite
                                                                                                             itself (Figure 8). Each stalactite has a removable pendentif inserted into a predisposed
                                                                                                             clearance hole on the lower end. In addition to these are other partially completed
                                                                                                             stalactites which enhance the perimetric muqarnas decoration in such a way that they
                                                                                                             create […] powerful shapes which form a signiicant interplay of masses and thus, of
                                                                                                             shadow and light, a succession of planes of varying levels that give a strong sense of
                                                                                                             moulding [2].




                                                                                                        76
                                                                                                        CONSERVATION SCIENCE IN CULTURAL HERITAGE
Figure 7. Top: intrados views of multi-lobed star on octagonal support and star-shaped module of
a cupoletta. Bottom: different construction systems used for the cupolettas.

    Above the ornamental shell-cornice running along the four walls in the area of the
central nave there is a wide decorative strip with a succession of registers, with niches,
deep recesses and highly protruding elements, that reaches an overall height of about
two linear metres. This is the part of the wooden ceiling that slopes very steeply and
described in the previous section as “system B”. It is made up of structural elements
consisting of vertical double planks that go off in various directions, with interposed
spacing/stiffening joists. The inishing structure to complete the muqarnas was then
arranged on top of these, with variegated forms and modules making up the four over-
lapping horizontal decorative registers. Operations to inalise and complete the work
were steadily carried out drawing on geometric Muslim matrices [7] shaped in accord-
ance with the diverse types of niches and the outwardly jutting parts of the muqarnas.
    The result is cavities of different sizes that overlap with each other in the various
registers, such as the one with a superior mixtilinear proile (just as an example) made
with lat slats for the bottom and small illets, about 5 mm thick, for the surface. Its so-
lidity was ensured using nails and pasted-on lint wood. Niches of a truncated-conical
shape, made from a series of small trapezoid shaped veneers, are laid out radially
and are also connected to the small wooden boards at the end with nails and strips of


                                                                                                   77
                                                                                                             wood-ibre and glue. In similar fashion, the elongated niches were given a barrel roof
                                                                                                             shape and those that constituted the brackets, a “cavetto” proile, useful for linking up
                                                                                                             the honeycomb decoration with the central portion of the ceiling, creating the charac-
                                                                                                             teristic steep progression of the projections (Figure 9).
G. Fatta, T. Campisi, M. Li Castri, G. Costa - The muqarnas ceiling of the Palatina Chapel in Palermo




                                                                                                             Figure 8. Intrados view of square central modules and stalactites. Decorative muqarnas registers,
                                                                                                             steeply inclined, in proximity of masonry.




                                                                                                             Figure 9. Construction details of decorative elements in the muqarnas registers.

                                                                                                                 Here, we shall limit ourselves to pointing out the rich imagination demonstrated in
                                                                                                             creating the areas that give rise to the honeycombs of various shapes and sizes, the
                                                                                                             differences linked to their position with regard to the structural ields, to the disposi-
                                                                                                             tion of the portion of the ceiling and to their proximity to the corners [7]. The systems
                                                                                                             for connecting the wooden elements vary primarily according to the structural role or
                                                                                                             inish of the parts to be linked. There is widespread use of nailing to join the different
                                                                                                             elements and varies depending on the material employed: from the bronze pins men-
                                                                                                             tioned by Cavallari to the iron elements which vary in length and nail-head section,
                                                                                                             often with curved ends in order to prevent extraction. The preparatory layers for the
                                                                                                             pictorial decoration consented many of these nail-heads to be concealed but became
                                                                                                             visible once more in those areas most affected by deterioration. As already suggested,
                                                                                                             the system of veneering the thinnest and most fragile wooden elements is widespread,


                                                                                                        78
involving binding with wood-ibre and animal glue to ensure adhesion between the lat
elements placed side by side along the slender edges and possibly substituted and/or
reinforced at a later date with extra binding in lax and hemp gauze [5].
   There are also reinforcing and connecting elements made from small wedges and
chocks, used to strengthen the structural parts that tend to become detached.


   5. Overhead structures and support beams for the ceiling

    In the large space above the muqarnas ceiling, there is a system of wooden and
metallic beams which, as previously noted, today constitutes an appropriate support
structure from which the monumental wooden ceiling is suspended. This is evidently a
posthumous addition, but it has proved most useful in containing the warping, shifting
and deformation of the parts, which might have caused considerable damage to the
structure and, in a worst-case scenario, the precious pictorial surfaces on the intrados.
    The afore-mentioned perimetric walkway on the extrados of the ceiling, allows ac-
cess to the entire interspace and facilitates inspection of the various orders of beams
supporting the muqarnas ceiling.
    A irst order, made up of four NP-160-type iron beams, was set in place by Franc-
esco Valenti in 1939 in the direction of the short side of the nave. Apart from supporting
the ceiling, the two opposite walls were connected by using longitudinal contrast sec-
tions (with a UPN 140) and tightening bolts.
    A second order comprises two pitch-pine purlins, each made up of two pairs of
beams (with a 5.5 x 211 cm section), set in place in 1894; a subsequent third order is
made up of 22 semi-square beams (of sections varying between 10 cm x155 cm and
13 cm x18 cm) dating back to the period of the late 19th century when work was carried
out to raise the central nave. Due to the absence of ventilation holes, some of these
beams had visibly deteriorated heads, causing a reduction of the section, surface whit-




                                                                                                     CONSERVATION SCIENCE IN CULTURAL HERITAGE
ening and loss of material compactness. Between the ordinary beams and the purlins
there is often a contrast wedge for “structural activation”, i.e. a steel corner ixed to the
beams with self-threading screws. The stringers resting simply on the beams beneath
might be considered a fourth order, with a variable length of 77cm - 290 cm and a sec-
tion of 5 cm x 55 cm to 8 cm x 16 cm.
    The wooden hanging units are connected to the stringers and the beams; they are
simple laths with an average section of about 3 cm x 8 cm and a variable length of
between 70 cm -160 cm. In all there are 174, of which 114 are nailed to the system of
semi-square beams and 60 to the longitudinal stringers. The connection is made on
the long side of the section of the “hanging unit” as well as on the short side. In the
latter case the lath often has a cavity which reduces the section. It has a regular and
sub-vertical shape in the lat part of the ceiling and is slightly inclined when it lies along
the perimetral strip of the ceiling [8, 9] (Figure 10).
    In the central nave, the whole structure of the Chapel is covered by a lat loor, con-
sisting of a simple framework of beams placed along the smaller span; the planking
on top was exposed for a long time to the inclemency of the weather and only in the
1980s was it provided with a temporary covering which, however, caused a micro-
climate that was most unsuitable for wooden structures. The removal of several parts
of the 17th century loor brought to light ancient looring in cocciopesto, about 4 cm
thick; the exposed surface is beaten and smoothed over and has an underlying screed


                                                                                                79
                                                                                                             containing signiicant pieces of cocciopesto of a more reined texture. Elevation of the
                                                                                                             outer walls is clearly visible, with an increase in the height of the springing line of the
                                                                                                             loor covering the central nave of about 1.10 m, compared to the original, presumably
                                                                                                             dating back to the Norman era. This stonework is different in both bond and thickness,
                                                                                                             consisting of perfectly square ashlars of bio-calcarenite up to a certain height. On top
                                                                                                             of this lies disorderly masonry made of rubble from demolition- waste, the wall spaces
                                                                                                             being illed with the bones of fowls, cloth remnants and even a shoe and spoon clearly
                                                                                                             of 17th century production.
G. Fatta, T. Campisi, M. Li Castri, G. Costa - The muqarnas ceiling of the Palatina Chapel in Palermo




                                                                                                             Figure 10. Wooden plank hanging supports connected to overlying structures and support beams
                                                                                                             for the ceiling, made of iron and wooden beams.



                                                                                                                6. Conclusions

                                                                                                                 In addition to the evident aesthetic quality and skilfully depicted scenes from life at
                                                                                                             that time, the wooden ceiling of the central nave of the Palatina Chapel also displays
                                                                                                             its uniqueness and exceptional qualities in the conception of its structural system and
                                                                                                             building design together with the techniques involved in producing the different compo-
                                                                                                             nent parts. It seems that the numerous interventions for maintenance, restoration and
                                                                                                             consolidation over the years have not greatly modiied the original structure, except in
                                                                                                             several structural joins /connections or marginal architectural elements.
                                                                                                                 Accurate analysis enabled us to understand how different types of wood came to
                                                                                                             be employed; although the wood probably came from Sicilian forests, only a number of
                                                                                                             the species used still exist on the island. The variety in its workability and mechanical
                                                                                                             resistance indicate it was used in different parts of the ceiling, from the long, straight
                                                                                                             “ribs” to the connecting planks, from the illets to the extremely thin slats used in shap-
                                                                                                             ing the niches, honeycombs and the more complex reliefs.
                                                                                                                 The investigation was facilitated by recently-executed cleaning operations which
                                                                                                             vacuum-cleaned the damaging quantity of dust and other deposits from the surface
                                                                                                             of the ceiling’s extrados. In many areas, these substances made it dificult to iden-
                                                                                                             tify the various elements involved in its construction. Furthermore, the utilization of


                                                                                                        80
brushes and scalpels consented removal of the encrustations and the more irmly
attached elements. The same operation was necessary for the hollow interiors of the
stalactites, which were full of rubble resulting from the demolition of the loor above,
pigeon-droppings and dust. The consequent increase in load, in several cases, might
well have contributed to some of the parts becoming detached. This material, which is
loose and consequently unstable in the case of horizontal forces, was also extracted
manually, thanks to the presence of the mounting hole of the wooden pendant-drops
at the tip of each stalactite.
    As regards the other conservation and restoration interventions on the ceiling’s ex-
trados, mention should be made of the cortical consolidation of certain parts, and the
revision of the wooden and metallic joints, with accurate re-bonding and substitution
of small, deteriorated parts. The intervention was completed by treating the extrados
surfaces with a ire-prooing spray.
    The study has conirmed the extraordinary nature of this great structure with regard
to both the originality of its technical and decorative solutions and the executive qual-
ity. This is the only example of wooden carpentry from the Islamic era still surviving
in Europe; it is also priceless in that it has remained almost totally immune to change
when compared to its original structure.
    The neat, modular sequence that is recognizable on the decorated intrados loses
a great part of its geometrical rigour in the apparent disorder of the extrados; its rustic
wood box-panels linked to each other in complex shapes and horizontal dispositions,
the increasingly thinner slats, nailing, the pivoting and gauze bandaging, ibre and
glue, all bear testimony to the incredible artisanal and artistic skills.
    Most surprising is the multi-branched, three-dimensional static model which relies
on very few precise elements for its support on the walls: with no risk of instability, 26
brackets manage to keep the precious ceiling safe from damaging external sources
of moisture. The large cornice at the base is also rich in decoration and inscriptions
and leads us to believe that it constitutes the perimetric supporting base for the ceiling,




                                                                                                           CONSERVATION SCIENCE IN CULTURAL HERITAGE
whereas, in reality, it is internally hollow. The behaviour of the whole structure and the
decorative inishing elements is thus revealed, the understanding of which seems es-
sential to evaluate the Chapel’s state of health and to plan possible future maintenance
and consolidation interventions.


   Acknowledgements

   The author would like to especially thank Calogero Vinci (engineer) for his coopera-
tion in the CAD drawings of the structural model of the ceiling.


   Notes

1
  The traveller Ibn Gyubair, in 1184, described the Palazzo Reale in Palermo and, in particular,
what one presumes was its “green room”: “[…]We went through squares, gates, royal courtyards
and saw splendid palaces, well-laid out exedras, gardens and rooms for public oficials, things to
dazzle one’s eyes and astonish one’s mind… apart from other things we noticed a hall in a large
courtyard surrounded by a garden and lanked by porticoes. The hall takes up the whole of the
courtyard, to the extent that we marvelled at its size, the height of the belvederes. We discovered
that this was the place where the king usually dined with his retinue. Opposite were the afore-


                                                                                                      81
                                                                                                             mentioned porticoes and the ofices where the magistrates, public oficials and the inance agents
                                                                                                             sat […]”.
                                                                                                             2
                                                                                                               The authors wish to thank Würth srl most heartily for their cooperation in consenting the use of
                                                                                                             images taken from the site archives, as well as the restoration-site operations management and
                                                                                                             the sole project manager.
                                                                                                             3
                                                                                                               A temporary entrepreneurial association (ATI) was set up between the irms “εartino Solito
                                                                                                             restauratore s.r.l.” (group chief), “Consorzio C.B. ART” of Marina Furci, “Studio C.R.C. S.r.l.” of
                                                                                                             Paolo Pastorello, Carla Tomasi and Sergio Salvati.
                                                                                                             4
                                                                                                               This opening was attributed to transformations undergone by the northern nave between 1786
                                                                                                             and 1795, for the construction of an access stairway to the Astronomical Observatory; see [4].
G. Fatta, T. Campisi, M. Li Castri, G. Costa - The muqarnas ceiling of the Palatina Chapel in Palermo




                                                                                                             5
                                                                                                               In 1891, on the occasion of the Esposizione Nazionale held in Palermo, the pavilions designed
                                                                                                             by Ernesto Basile housed three wooden models of the ceiling, today conserved at the Accademia
                                                                                                             di Belle Arti in Palermo. In 18λ3 Alexis Pavlosklij published the irst thorough and precise analysis
                                                                                                             of the stylistic features of the ceiling, as well as an Islamic attribution for the pictorial cycle.


                                                                                                                   References

                                                                                                             [1]  Amari, M., Boglino, L., Carini, I., Cavallari, F. S., Terzi, A. (1889). La Cappella di
                                                                                                                  S. Pietro della Reggia di Palermo. Palermo.
                                                                                                             [2] Monneret de Villard, U. (1950). δe pitture musulmane al sofitto della Cappella
                                                                                                                  Palatina in Palermo. Palermo.
                                                                                                             [3] Li Castri, M., Campisi, T., Fatta, G. (2006). Timbered coverings and ceilings of
                                                                                                                  the Palatina Chapel in Palermo. Materials, constructive techniques, restorations,
                                                                                                                  Why save historic timber structures? In:15th IIWC International Conference and
                                                                                                                  Symposium Proceedings. Istanbul.
                                                                                                             [4] Trizzino, L. (1983). La Palatina di Palermo, Palermo.
                                                                                                             [5] Zoric, V. (2005). Sulle tecniche costruttive islamiche in Sicilia: il sofitto della Cap-
                                                                                                                  pella Palatina di Palermo. In: Bernardini, M., Tornesello, V.L. (eds.) Scritti in on-
                                                                                                                  ore di Giovanni M. D’Erme: Napoli.
                                                                                                             [6] Pavloskij, A. (1893). Decorations des plafonds de la Chaspelle Palatine, Byzan-
                                                                                                                  tinische Zeitschrift, 2,3. Munich.
                                                                                                             [7] Agnello, F. (2010). Rilievo e rappresentazione del sofitto della navata principale
                                                                                                                  della Cappella Palatina. In: Beat Brenk (ed.) The Cappella Palatina in Palermo.
                                                                                                                  Modena.
                                                                                                             [8] Li Castri, M., Campisi, T., Agnello, F. (2007). The Muqarnas Wooden Ceiling
                                                                                                                  and the Nave Rooing in the Palatina Chapel of Palermo: geometries, failures
                                                                                                                  and restorations, poster presented at the international symposium From Material
                                                                                                                  to Structure – εechanical Behaviour and Failures of the Timber Structures. In:
                                                                                                                  Icomos IWC -16th International Symposium. Florence, Venice and Vicenza.
                                                                                                             [9] Costa, G. (2007). δa struttura di supporto del controsofitto ligneo a muqarnas
                                                                                                                  della Regia Cappella Palatina di San Pietro nel Palazzo dei Normanni a Palermo:
                                                                                                                  analisi costruttiva e progetto di restauro e miglioramento sismico, master thesis
                                                                                                                  (II level) in “Restauro, Protezione e Sicurezza degli Ediici Storici e εonumen-
                                                                                                                  tali”, (supervisor Prof. Gennaro Tampone).
                                                                                                             [10] Brandi, C. (1989). “La Cappella Palatina di Palermo”, sta in Sicilia mia. Sellerio:
                                                                                                                  Palermo.
                                                                                                             [11] Li Castri, M. and Campisi, T. (2007). The Muqarnas wooden ceiling and the Nave
                                                                                                                  rooing in the Palatina Chapel of Palermo: geometries, failures and restorations.
                                                                                                                  In: Proceedings of the 16th International Symposium of the IIWC, Firenze.


                                                                                                        82
[12] Lavisci, P. and Mannucci, M. (1999). Legno - Diagnosi e restauro. Recupero &
     Conservazione, 26.
[13] Genovese, C. and Valenti, F. (2010). Restauro dei monumenti nella Sicilia del
     primo Novecento. Edizioni Scientiiche Italianeμ Napoli.


   Biographical notes

   Giovanni Fatta (Palermo, 1949), graduated in Building Engineering at the University
of Palermo. He is full professor of Technical Architecture and works in the Department of
Architecture at the University of Palermo, where he teaches Rehabilitation and Conser-
vation Design of historical architecture. He has been Head of Department, Coordinator
of the PhD Course and Master in “Building Rehabilitation”, President of the Research
Committee for the University of Palermo (Area 08); he has coordinated national research
groups. He has frequently acted as a “blind referee” for the evaluation of research pro-
jects and reports presented at international congressesν he is a member of Scientiic
and Editorial Committees of qualiied scientiic journals. He has been a member of Com-
mittees for the comparative evaluation of candidates applying for position of professor
or lecturer at several Italian Universities. His research and ield of publication cover the
analysis of materials and techniques of historical architecture and architectural and envi-
ronmental recovery, with particular attention to the Sicilian context.

    Tiziana Campisi (Palermo, 1972), Architectural Building engineer, PhD, is associ-
ate professor of Technical Architecture and works at the Department of Architecture of
the University of Palermo. She teaches “Technical Architecture” and has taught “His-
tory of construction techniques” for the ive-year degree course in “Building Engineer-
ing-Architecture”; she has collaborated in academic courses related to architectural
rehabilitation and restoration. Her research is mainly related to the analysis and study




                                                                                                   CONSERVATION SCIENCE IN CULTURAL HERITAGE
of traditional building techniques, concerning both the Sicilian and European area and
the compatible rehabilitation of historical architecture. She has written more than 100
essays on books, as articles in national and international scientiic journals and pro-
ceedings; she is the author of books, some of them concerning the study of historical
wooden structures. She is a member of national and international associations and in-
stitutions that deal with the construction history, architectural technology of and valori-
zation and safeguard of architectural heritage (RehabiMed Association, Construction
History Society, Italian Icomos wooden Committee section, Artec Association).

   Mario Li Castri (Palermo, 1967), architect, PhD, research fellow, has taught Archi-
tectural Restoration, Technical Architecture and Urban Planning legislation for public
works on degree courses at the Universities of Palermo and Messina; he has also
taught in post-graduate university courses. He is manager of the Technical Ofice at
the εunicipality of Palermo. He has carried out research in the ields of restoration and
recovery of monumental and historical architecture, of planning, design and execution
of public building works. He has been invited to speak at national and international
Conferences and is the author of numerous scientiic publications.

   Giuseppe Costa (Erice, 1980), has a degree in Architectural-Building Engineering
from the University of Palermo (2006), discussing a thesis about the recovery design


                                                                                              83
                                                                                                             of a rural building complex. In 2008 he frequented the University of Florence, doing a
                                                                                                             Master’s Degree in “Restoration, protection and safety of historic buildings and monu-
                                                                                                             ments”; in 2011, he obtained his PhD at the University of Palermo, with a PhD thesis
                                                                                                             on non-hydraulic cement mortars. In 2012, he became an engineer of the Technical
                                                                                                             Ofice of the Italian Navy, infrastructure section, and currently has a position at the Of-
                                                                                                             ice of the Army Corps of Engineers for ε.ε. Schools, inside the Arsenale district of
                                                                                                             Venice. He has carried out research on materials and construction techniques used
                                                                                                             in the historical building heritage of western Sicily, publishing in international journals
                                                                                                             and conferences.
G. Fatta, T. Campisi, M. Li Castri, G. Costa - The muqarnas ceiling of the Palatina Chapel in Palermo




                                                                                                                 Summary
                                                                                                                 St. Peter’s Basilica inside the Royal Palace of Palermo, known as the Palatina
                                                                                                             Chapel, is one of the most popular medieval monuments in Sicily. Built between 1130
                                                                                                             and 1163, it contains interesting wooden framings that represent both bearing and
                                                                                                             inishing structures.
                                                                                                                 Studies on the Arab-Norman church have often concentrated on the very rich and
                                                                                                             suggestive decorative mosaic apparatus of walls and loorings, as well as the pictorial
                                                                                                             cycle of wooden ceilings. Knowledge about the constructive techniques adopted and
                                                                                                             in particular, about the realization of the coverings, is very limited: there are wooden
                                                                                                             loors built at different levels, vaults and wooden ceilings and among these is the por-
                                                                                                             tion that covers the main nave, housing the muqarnas decorations.
                                                                                                                 The fortunate coincidence of the restoration building yard made it possible to gain
                                                                                                             precious knowledge of this extraordinary wooden structure, also through a laser scan-
                                                                                                             ning survey of a signiicant area of the wooden ceiling, performed with a low range
                                                                                                             device. The collected data adequately represent the geometry and the state of conser-
                                                                                                             vation of the ceiling and have been used to develop a spatial and geometrical analysis
                                                                                                             of the muqarnas and relate it to the structural layout.
                                                                                                                 The survey of the internal and external sides of the covering enabled us to investi-
                                                                                                             gate further the materials and constructive techniques employed in this ancient wood-
                                                                                                             en ceiling. At the same time, we were also able to document the original structural
                                                                                                             system and the completion parts, its conservation status and the interventions and
                                                                                                             modiications it has undergone through many centuries.

                                                                                                                Riassunto
                                                                                                                La Basilica di San Pietro, all’interno del Palazzo Reale di Palermo, nota anche
                                                                                                             come Cappella Palatina, è uno dei monumenti medievali più conosciuti in Sicilia. Cos-
                                                                                                             truita tra gli anni 1130 e 1163, contiene opere di carpenteria lignea di grande interesse,
                                                                                                             sia dal punto di vista strutturale che per quanto attiene gli aspetti decorativi.
                                                                                                                Gli studi sulla chiesa arabo-normanna si sono il più delle volte concentrati sul ricco
                                                                                                             e suggestivo apparato musivo, sia sulle pareti che nelle pavimentazioni, così come sul
                                                                                                             ciclo pittorico dei sofitti in legno. δa conoscenza delle tecniche costruttive adottate e, in
                                                                                                             particolare, dei sistemi di impalcato della copertura, è molto limitata: si ritrovano solai di
                                                                                                             copertura impostati a quote differenti, ma anche volte e sofitti in legno e, fra tutti, partico-
                                                                                                             lare qualità ha il sofitto decorato a muqarnas che copre la navata principale.
                                                                                                                La fortunata coincidenza del cantiere di restauro ha permesso di acquisire preziosi
                                                                                                             elementi di conoscenza di questa straordinaria struttura in legno, anche attraverso un


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rilievo a mezzo di scansione laser di un’importante area del sofitto a muqarnas es-
eguita con un dispositivo a bassa portata. I dati raccolti rappresentano adeguatamente
la geometria e lo stato di conservazione del sofitto e sono stati utilizzati per sviluppare
un’analisi spaziale e geometrica del sofitto stesso di correlarla allo schema statico-
strutturale.
    L’indagine sia all’estradosso che all’intradosso ha permesso di approfondire i mate-
riali e le tecniche costruttive impiegate per la realizzazione di questo sofitto in legno.
Allo stesso tempo, si sono potuti documentare sia l’originale sistema strutturale che le
parti di completamento, lo stato di conservazione e gli interventi e le modiiche subiti
nel corso dei secoli.




                                                                                                   CONSERVATION SCIENCE IN CULTURAL HERITAGE




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