10.6092/issn.1973-9494/7120
Nella cornice di un programma di formazione in Cambogia, durante una visita al Museo Nazionale di Phnom Penh, il più importante nel Regno di Cambogia, gli autori hanno notato la presenza di alcuni segni di attacco di termiti negli elementi secondari del tetto di un giardino interno. In base a questa osservazione, un’ulteriore indagine fu effettuata per valutare la condizione fitosanitaria dell’elemento portante in legno del tetto. L’ispezione ha evidenziato la presenza di un grave decadimento che costituiva un chiaro pericolo per l’integrità del tetto, dunque un intervento di restauro, conservazione e salvaguardia è stato considerato come necessario ed urgente. In questo lavoro sono presentati i risultati del lavoro di indagine sullo stato di conservazione delle strutture portanti in legno del Museo Nazionale di Phnom Penh, Regno di Cambogia; inoltre è riportata una proposta di intervento correttamente progettato per la salvaguardia contro le termiti per un lungo periodo di tempo.
application/pdf
1973-9494
7120
2
en
Giovanni Liotta
Conservation Science in Cultural Heritage
Phnom Penh National Museum
Biodeterioration of the Wooden Roof of the Phnom Penh National Museum
Text.Serial.Journal
https://conservation-science.unibo.it/
15
Articles
2017-06-01
2017-07-04
2017-06-01
2017-09-04
73-83
CSCH
Giovanni Liotta
2015
10.6092/issn.1973-9494/7120
73
Università di Palermo
1973-9494
2
Phnom Penh National Museum
en
83
Biodeterioration of the Wooden Roof of the Phnom Penh National Museum
https://conservation-science.unibo.it/article/download/7120/6830
15
B     IODETERIORATION OF THE WOODEN ROOF OF THE
      PHNOM PENH NATIONAL MUSEUM

    Bartolomeo Megna*, Giovanni Liotta 6
    Laboratory of Materials for Restoration and Conservation, Dipartimento di Ingeg-
    neria Civile, Ambientale, Aerospaziale, dei Materiali, Università di Palermo, Italy


    Keywords: termites, wooden structures, Phnom Penh National Museum


    1. Introduction

    In the framework of an international training program organized by the University of
Palermo in Siem Reap, Kingdom of Cambodia, during a visit to the National Museum in
Phnom Penh, the Authors noted signs of termite attack on the external wooden beams
of the southern portico of the inner garden (see Figure 1).
    Considering the risk connected to the presence of such insects in a wooden struc-
ture, a preliminary investigation of the roof was performed in order to verify the pres-
ence of termites in other parts, particularly in the bearing elements of the roof struc-
tures as, in an anthropic environment, termites represent a high risk level for wooden
elements [1-10].




                                                                                                           CONSERVATION SCIENCE IN CULTURAL HERITAGE




Figure 1. A) Floor plan of the museum; the black arrow indicates the place where signs of termite
infestation were noted; the blue frame indicates fungi infestation; the red frame indicates termite
infestation; the green area indicates the observed concrete structure. B) The external wooden
element damaged by termites.


   Identification of the termite species is very important for the proper design of any
restoration intervention. In fact, drywood termites (e.g. Kalotermitidae) have colonies
consisting of a few thousand individual the various castes and the whole nest is within
the wooden element they feed on [11, 12]; on the contrary, colonies of subterranean


*   Corresponding author: bartolomeo.megna@unipa.it

                                                                                                      73
                                                                                                   termites (e.g. Rhinotermitidae) consist of several hundreds of thousands of individuals
                                                                                                   (up to more than one million) and have their nest in the ground. They move back and
                                                                                                   forth between the nest and the wooden elements they feed on by passing through dark
                                                                                                   galleries that they build using excrements and soil grains glued together with saliva.
                                                                                                   The latter are definitely the most destructive [11-15]. These biological differences re-
                                                                                                   quire different methodologies for disinfestation and preventive conservation.
B. Megna, G. Liotta - BIODETERIORATION OF THE WOODEN ROOF OF THE PHNOM PENH NATIONAL MUSEUM




                                                                                                      The National Museum in Phnom Penh is the largest Cambodian museum of cultural
                                                                                                   history and is the country’s leading historical and archaeological museum. The mu-
                                                                                                   seum roof bearing structure consists of wooden A-frame elements, a drawing of which
                                                                                                   is shown in Figure 1. The Museum buildings, inspired by Khmer temple architecture
                                                                                                   (George Groslier), were built between 1917 and 1924. The wood used in the structure
                                                                                                   has not been identified, as the available samples were too rotten to be observed under
                                                                                                   the microscope.

                                                                                                      2. Previous restoration intervention

                                                                                                      It should be highlighted that a recent restoration intervention was performed in the
                                                                                                   north wing of the building due to the presence of severe termite infestation as reported
                                                                                                   by a museum restorer.
                                                                                                      The intervention consisted in the substitution of the decayed wooden beams, con-
                                                                                                   sidered unfit to bear the required load, with brand new ones. The latter underwent
                                                                                                   insecticide treatment performed by brush application of a liquid insecticide, mostly in
                                                                                                   the end grain or in the joints of the beams (see Figure 2). Signs of this treatment could
                                                                                                   be easily noted due to the visible brown stain of the product used.
                                                                                                      It could be noted that most of the original wooden elements were not substituted
                                                                                                   in spite of the presence of termite walkways on the surfaces, probably assuming that
                                                                                                   massive use of the insecticide could stop the ongoing infestation. Unfortunately this
                                                                                                   assumption is valid only in the case of drywood termites; the pathways were not con-
                                                                                                   sidered as being used only to move from one feeding place to another, while most of
                                                                                                   the termite population lived safely within the nest, where it cannot be reached by any
                                                                                                   treatment performed from the surface. Moreover, this approach would only be effective
                                                                                                   for drywood termites, as the colony lives in the feeding place, but totally ineffective for
                                                                                                   subterranean termites, as the colony mostly lives far from the feeding place inside the
                                                                                                   nest, that could be located dozens of meters away from the roof.
                                                                                                      Finally, the removed beams were stored in Garden S of the building (see Figure 1),
                                                                                                   very close to the new wooden beams, acting as a decoy for a new infestation.

                                                                                                      3. Results of inspection

                                                                                                      The main goal of this investigation was to verify the phytosanitary condition of
                                                                                                   the wooden roof of the National Museum in order to prepare, where needed, sug-
                                                                                                   gestions for its safeguard and the proper precautionary steps for its conservation.
                                                                                                   Starting from a preliminary observation in the south colonnade of the inner garden,
                                                                                                   the investigation moved to the main and secondary wooden structures of the north
                                                                                                   wing of the Museum roof.
                                                                                                      Before starting the inspection of the wooden structures the concrete structures were
                                                                                                   observed to evaluate their conservation state in relation to environmental conditions.
                                                                                                   The conservation state of the concrete was surprisingly quite good and only some mi-


                                                                                              74
nor corrosion was detected at the top of the roof, despite the structure being 40 years
old (see Figure 2). The presence of corrosion was probably caused by water conden-
sation occurring at the top of the roof.
    Study of the wooden structures was in two parts. The first was an in situ visual
examination, primarily focused on the heads of the primary and secondary beams, as
they usually suffer biologically induced decay due to water condensation which forms
on the wood as a result of its contact with walls. The second part was a microscopic
investigation of samples collected during the inspection, consisting of powdered mate-
rial taken from all meaningful parts of the structure.




Figure 2. Concrete structure of the roof: A) base of the concrete structure with no visible corrosion
of reinforcing steel bars; B) top of the structure with clear signs of corrosion.

   At first sight, the previous insecticide treatment was easily individuated as the wood




                                                                                                             CONSERVATION SCIENCE IN CULTURAL HERITAGE
appeared darker where the insecticide had been applied, as shown in Figure 3; moreo-
ver, signs of the termites’ walkways were identified both on the original wooden beams
and on the new ones (Figure 4 A and B), highlighting that termite infestation was ac-
tive after the restoration and had spread to the recently introduced wooden beams.
The presence of the ghost trace of a termite walkway (probably removed in the past
intervention) beside the new walkways, highlights the ineffectiveness of the insecticide
treatment.




Figure 3. A) Insecticide used in the previous restoration intervention; B) treated end grain of an
old rafter; C) sign of insecticide treatment on new beams of the roof.




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B. Megna, G. Liotta - BIODETERIORATION OF THE WOODEN ROOF OF THE PHNOM PENH NATIONAL MUSEUM




                                                                                                   Figure 4. A) The blue arrow indicates a termite walkway on an old rafter, the red one indicates
                                                                                                   ghost traces of the walkway removed during the previous intervention; B) termite walkways on
                                                                                                   newly installed rafter.

                                                                                                       As the bearing structures of the roof are installed over large tie beams going from
                                                                                                   one wall to the opposite one, forming the base of the A shape structural truss element
                                                                                                   bearing the whole roof, particular attention was paid to these elements. Some of the
                                                                                                   large tie beams resting on the brick walls showed severe deterioration of the end grain,
                                                                                                   induced by termites, while the remaining part of the beams appeared to be in good
                                                                                                   condition (Figure 5B); unfortunately, even though the external wooden surface appears
                                                                                                   sound, termites can act inside the wood. In particular, when the wood was hammered,
                                                                                                   the resulting sound clearly indicated the presence of large voids within: widespread
                                                                                                   termite galleries could be observed by removing the thin wooden film on the surface
                                                                                                   along the whole beam (Figure 5C). The decay appears to be quite severe as the gal-
                                                                                                   leries pass over the support area indicating a clear risk of failure (Figure 5F).
                                                                                                       On closer examination, it was possible to observe that the termites had hollowed
                                                                                                   out the wood, severely reducing the section and consequently its mechanical proper-
                                                                                                   ties. In the north-east corner of the roof structure (Figure 5D), there was some evident
                                                                                                   danger, as the wooden bearing tie beam was filled with recently constructed termite
                                                                                                   cells (Figure 5E); moreover, several termites were noted, indicating an ongoing active
                                                                                                   infestation (Figure 5C).
                                                                                                       Continuing further with removal of the termites’ nest, it was possible to observe that
                                                                                                   no wood was left in the beam head (Figure 5F). In these conditions, the whole roof was
                                                                                                   clearly in danger of collapsing.
                                                                                                       In addition, some of the roof prop beams showed clear signs of termite attack. One
                                                                                                   of the prop beams in particular was found to be broken in the middle as a result of the
                                                                                                   weight of the vertical poles connected to it, with no residual mechanical function, which
                                                                                                   indicated the presence of a large number of termite galleries within (Figure 6c).
                                                                                                       Finally, the pitches of the lateral colonnade of the inner garden were slightly sloped;
                                                                                                   according to this geometrical consideration, it would be possible for water to reach the
                                                                                                   wooden structures under the roof in the case of heavy rain and strong winds. These
                                                                                                   wooden beams in effect showed clear signs of fungi infestation, due to high water con-
                                                                                                   tent, even if transient (Figure 7a).
                                                                                                       It is well known that a high water content in wood, particularly in the presence of
                                                                                                   fungi, attracts insects and particularly termites. Taking this point into consideration, the


                                                                                              76
Figure 5. A) End grain of a tie beam decayed by termites; B) apparently sound tie beam, C) after
removal of the thin wood surface layer; D) the red circle indicates the position of the structural
corner element in the Museum floor plan; E) termite gallery extracted from the end grain; F)
hollowed out wood in the end grain of the corner tie beam.




                                                                                                          CONSERVATION SCIENCE IN CULTURAL HERITAGE
Figure 6. a) Termite pathways on a roof bearing beam; b) the same beam after the removal of the
wood surface; c) collapsed horizontal prop beam, caused by termite infestation.



presence of termites in the tie beams of the trusses of the colonnade roof was inves-
tigated. It was possible to note that all the shrinkage cracks were filled with a granular
material (Figure 7b). Sampling and direct observation of this material were performed
and identified as termite faeces, commonly used by termites to build their tunnels or
walkways. In general, these walkways or tunnels have to be perfectly sealed as ter-
mites are scared by light. The termite population was large and active (Figure 7c), as
clearly observed when the walkways along the whole beam were broken; in all investi-
gated points, a large number of living insects were seen to spread out from the wood.
This observation confirmed that termite presence was widespread and abundant.
   The termites responsible for the attacks on the wooden structures of the roof of
the National Museum in Phnom Penh belong to the family of Rhinotermitidae and
to the species of Coptotermes gestroi. This species is native to South East Asia but
nowadays is widespread in other continents. It is one of the most dangerous species


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B. Megna, G. Liotta - BIODETERIORATION OF THE WOODEN ROOF OF THE PHNOM PENH NATIONAL MUSEUM




                                                                                                          Figure 7. Colonnade beam: a) fungi signs; b) termite pathways; c) living termites.


                                                                                                   for wood. Coptotermes gestroi, as all other species belonging to the Rhinotermitidae
                                                                                                   family, are subterranean termites, i.e. they build their nest in the soil and the workers
                                                                                                   spread all around to find wet wood to feed on, reaching places that are quite far from
                                                                                                   the nest (dozens of meters) [15]. The Coptotermes gestroi species attack only wooden
                                                                                                   structures with a high moisture content. Once they start infestation, they can spread to
                                                                                                   nearby dry wooden elements because these termites are able to create by themselves
                                                                                                   a proper environment for their activity, potentially leading to very serious damage. In
                                                                                                   the roof environment, the main cause of high humidity is probably the occurrence of
                                                                                                   condensation phenomena. One way to prevent humidity from condensation is to en-
                                                                                                   sure good air circulation [16-18].




                                                                                                                       Figure 8. Coptotermes gestroi: A) worker; B) soldiers.

                                                                                                       The investigation was also extended to the west wing of the roof. In this part of the
                                                                                                   structure there was no sign of termites, but a large fungi infestation was clearly present
                                                                                                   and active (Figure 9). Visual investigation and knocking on the wood beams indicated
                                                                                                   that the decay was affecting only the surface of all the wooden elements. It should be
                                                                                                   highlighted that fungi infestation is mostly present at the top of the roof, indicating that
                                                                                                   the main cause of the high humidity is the condensation occurring when hot humid air
                                                                                                   reaches the cool top of the roof. Nevertheless, the restoration intervention on the roof
                                                                                                   must be designed to reduce the relative humidity in the garret ensuring good air circu-
                                                                                                   lation throughout the entire roof.


                                                                                              78
       Figure 9. Detail of the fungi infestation found in the west wing of the Museum roof.



   4. Proposal of intervention

    Suitable measures have to be taken to maintain good air circulation in the Mu-
seum garret in order to reduce or avoid the settling of new termite infestation. The
first step of the recovery will be the disinfestation of all the termite infested beams in
the roof and in the colonnade, by means of Cypermethrin (Cyano-(3-phenoxyphenyl)
methyl]3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carboxylate) base prod-
uct. The second step will be the removal of all elements showing signs of termite
attack. All the removed wood must be burnt. The insecticide has to be applied by
pressure injection, an awkward operation that has to be performed by specialized
operators. The beams severely attacked by fungi have to be removed too and all
the surrounding wooden elements have to be treated with a 10% solution of Benza-
lkonium chloride, also known as alkyldimethylbenzylammonium chloride (ADBAC),
applied by brushing.
    The last step in the recovery intervention will be the sanitization of the soil all around
the Museum against the species, Coptotermes gestroi. To achieve this result, a prod-




                                                                                                      CONSERVATION SCIENCE IN CULTURAL HERITAGE
uct such as hexaflumuron should be used which is able to affect the growing process
of the termites and lead to the destruction of the entire nest [19-21].

   4.1 Measures for long term safeguard and conservation

    All the new beams should be treated with the same products previously used
for the old parts.The heads of the new beams should not be put in direct contact
with the walls, in order to facilitate moisture exchange with the air and avoid the
settling and development of new termite infestation or fungi infection. It is essen-
tial to create in all the garrets, a good system of air circulation in order to avoid
condensation phenomena and prevent new settling of biodeterioration agents. It
should be sufficient to ensure the presence of open gaps between the beams as
shown in Figure 10A, in all parts of the roof. It is also necessary to avoid the mis-
takes highlighted in Figure 10B and 10C, where the gaps are sealed with tape or
mortar, respectively. In order to increase air circulation and prevent a high level of
humidity in the garret, a 50 x 50 cm window has to be created at the top of each
gable in the roof.These windows will be designed properly to prevent rain water
from entering.




                                                                                                 79
B. Megna, G. Liotta - BIODETERIORATION OF THE WOODEN ROOF OF THE PHNOM PENH NATIONAL MUSEUM




                                                                                                   Figure 10. Roof structure: A) open gap between the folds of the roof; B) open gap between the
                                                                                                   folds sealed with tape; C) open gap between the folds sealed with mortar.


                                                                                                      5. Conclusive remarks

                                                                                                       This paper presents the preliminary study for the conservation of the wooden roof of
                                                                                                   the National Museum in Phnom Penh. The study starts from a visual inspection of the
                                                                                                   external elements of the roof and goes on to identify the termite species responsible
                                                                                                   for the decay. Moreover, some proposals have been suggested to improve the envi-
                                                                                                   ronmental condition of the roof and to ensure the long-term safeguard of the structure.
                                                                                                       The observations reported in this case study offer the opportunity to develop some
                                                                                                   interesting advice on termite-decayed wooden structures.
                                                                                                       As a first point, it is evident that the old restoration intervention was ineffective,
                                                                                                   as the termite infestation returned after one year and today is more widespread than
                                                                                                   before. This fact appears to be related to some controversial decision in the previous
                                                                                                   intervention such as: old and new timbers being mixed in the structure, regardless of
                                                                                                   the presence of termite walkways on some old elements; no modification was made in
                                                                                                   the garret environment, no new openings were created to increase air circulation; old
                                                                                                   timbers attacked by termites were stored close to the building and the termites’ nest
                                                                                                   was not identified and eradicated. It is very important to note that the use of an effec-
                                                                                                   tive insecticide is not enough in treating subterranean termite infestation because the
                                                                                                   insecticide is only able to kill the termites present in the timber elements while the main
                                                                                                   part of the nest population is safe in the ground.
                                                                                                       As a second point, the wood severely attacked by termites shows a clean, appar-
                                                                                                   ently healthy surface, even if the infestation is ongoing: it is very important to look for
                                                                                                   small signs of the termites’ presence, such as walkways in the wooden elements or in
                                                                                                   the walls, filling of shrinkage cracks. As shown in this paper, the infestation could have
                                                                                                   totally decayed the wooden elements without affecting the surface.
                                                                                                       As subterranean termites are quite widespread in Cambodia, the only effective
                                                                                                   long-term safeguard consists in the environmental control of relative humidity in order
                                                                                                   to lower wood moisture content in the wooden elements.




                                                                                              80
      References

[1]     Harris, W.V., (1971) Termites: Their Recognition and Control. London: Longman
        Group Ltd.
[2]     Hichin, N.E., (1971) Termites-a world problem. UK: Hutchinson.
[3]     Edwards, R., Mill, A.E., (1986) Termites in buildings. Their biology and control.
        UK: Rentokil Ltd.
[4]     Lee, C.Y., (2002) Subterranean termite pests and their control in the urban envi-
        ronment in Malaysia, Sociobiology, 40(1), pp. 3-10.
[5]     Pearce, M.J., (1997) Termites: biology and pest management. UK: CAB Interna-
        tional.
[6]     Lee, C.Y., Chung, K.M., (2003) Termites. In Urban Pest Control - A Malaysian
        Perspective, University Sains Malaysia, pp. 99-111.
[7]     Clement, J.L., Bagneres, A.G., Uva, P., Wilfert, L., Quintana, A., Reinhard, J,
        Dronnet, S., (2001) Biosystematics of Reticulitermes termites in Europe: Mor-
        phological, chemical and molecular data, Insectes Sociaux, 48(3), pp. 202-215.
[8]     Constantino R., (2002) The pest termites of South America: taxonomy, distribu-
        tion and status, Journal of Applied Entomology, 126(7-8), pp. 355-365.
[9]     Su, N-Y., Scheffrahn, R.H., (2000) Termites as pests of buildings, Termites: evo-
        lution, sociality, symbioses, ecology. Kluwer Academic Publishers, pp. 437-453.
[10]    Kambhampati, S., Eggleton, P., (2000) Taxonomy and phylogeny of termites.
        Termites: evolution, sociality, symbioses, ecology. Kluwer Academic.
[11]    Roonwal, M.L., (1970) Termites of the Oriental Region. In: Biology of Termites,
        vol. II. New York and London: Academic Press, pp. 315-391.
[12]    Tho, Y.P., Kirton, L.G., (1992) The economic significance of Coptotermes ter-
        mites in Malaysian forestry, in Proceedings of the 3rd International Conference
        on Plant Protection in the Tropics, Volume IV, Genting Highlands, Malaysia.
[13]    Sornnuwat, Y., Tsunoda, K., Yoshimura, T., Takahashi, M., Vongkaluang, C.,




                                                                                                     CONSERVATION SCIENCE IN CULTURAL HERITAGE
        (1996) Foraging populations of Coptotermes gestroi (Isoptera: Rhinotermitidae)
        in an urban area, Journal of Economic Entomology, 89(6), pp. 1485-1490.
[14]    Ahmad Said, S., Yaacob, A.W., (1997) Termites from selected building premises
        in Selangor, Peninsular Malaysia, Malaysian Forester, 60, pp. 203-215.
[15]    Kirton, L.G., Wong, A.H.H., (2001) The economic importance and control of ter-
        mite infestations in relation to plantation forestry and wood preservation in Pen-
        insular Malaysia - an overview, Sociobiology, (37)2, pp. 325-350.
[16]    Liotta, G., (1987) Le termiti e i manufatti lignei, I Congr. Naz. Legno nel restauro
        e restauro del legno. Palutan ed. Milano, pp. 83-86.
[17]    Liotta, G., (1991) Gli insetti e i danni del legno - Problemi di restauro. Firenze:
        Nardini Editore.
[18]    Liotta, G., (2005) Le termiti agenti di degrado delle strutture lignee dei beni cul-
        turali, in Proc. of the International Conference “Conservation of Historic Wooden
        Structures”, vol. 1, pp. 3-10.
[19]    Miller, E.M., (1969) Caste differentiation in the lower termites. In: Biology of Ter-
        mites, vol. 1. New York and London: Academic Press.
[20]    Sajap, A.S., Amit, S., Welker, J., (2000) Evaluation of hexaflumuron for control-
        ling the subterranean termite Coptotermes curvignathus (Isoptera: Rhinotermiti-
        dae) in Malaysia. Journal of Economic Entomology, 93(2), pp. 429-433.



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                                                                                                   [21] Su, N., Hillis-Starr, Z., Ban, P, Scheffrahn, R., (2003) Protecting historic proper-
                                                                                                        ties from subterranean termites: a case study with Fort Christiansvaern, Chris-
                                                                                                        tiansted National Historic Site, United States Virgin Islands, American Entomolo-
                                                                                                        gist, pp. 20-32.
B. Megna, G. Liotta - BIODETERIORATION OF THE WOODEN ROOF OF THE PHNOM PENH NATIONAL MUSEUM




                                                                                                      Biographical notes

                                                                                                      Bartolomeo Megna is a senior researcher in Science and Technology of Materials
                                                                                                   at the DICAM Department of Palermo; he has always been interested in the theme
                                                                                                   of conservation of cultural heritage; he has a PhD with a thesis on materials for the
                                                                                                   recovery of wooden artifacts.
                                                                                                      Giovanni Liotta former full professor of Agricultural Entomology at the University of
                                                                                                   Palermo; he has a vast curriculum of research and interventions on cultural heritage
                                                                                                   subject to entomological attack, especially in wooden structures, library collections,
                                                                                                   etc.. He is the author of several books on the subject, including: “Gli insetti e i danni del
                                                                                                   legno. Problemi di restauro”; “Agli insetti piacciono le opere d’arte”.




                                                                                              82
   Summary
   Within the framework of a training program in Cambodia, during a visit to the Nation-
al Museum in Phnom Penh, the most important in the Kingdom of Cambodia, the au-
thors noted the presence of some signs of a termite attack in the secondary elements
of the roof of an inner garden. Following this observation, a further investigation was
performed in order to evaluate the phytosanitary condition of the wooden bearing ele-
ment of the roof. The inspection highlighted the presence of severe decay, constituting
a real danger for the integrity of the roof; consequently, an intervention of restoration,
conservation and safeguard was considered to be necessary and urgent. This paper
presents the results of the investigation of the conservation state of the load bearing
wooden structures of the National Museum in Phnom Penh, Kingdom of Cambodia;
moreover, a proposal is put forward for a properly designed intervention to safeguard
against the termites in the long term.


    Riassunto
    Nella cornice di un programma di formazione in Cambogia, durante una visita al
Museo Nazionale di Phnom Penh, il più importante nel Regno di Cambogia, gli autori
hanno notato la presenza di alcuni segni di attacco di termiti negli elementi secondari
del tetto di un giardino interno. In base a questa osservazione, un’ulteriore indagine
fu effettuata per valutare la condizione fitosanitaria dell’elemento portante in legno del
tetto. L’ispezione ha evidenziato la presenza di un grave decadimento che costituiva
un chiaro pericolo per l’integrità del tetto, dunque un intervento di restauro, conser-
vazione e salvaguardia è stato considerato come necessario ed urgente. In questo
lavoro sono presentati i risultati del lavoro di indagine sullo stato di conservazione delle
strutture portanti in legno del Museo Nazionale di Phnom Penh, Regno di Cambogia;
inoltre è riportata una proposta di intervento correttamente progettato per la salvaguar-
dia contro le termiti per un lungo periodo di tempo.




                                                                                                    CONSERVATION SCIENCE IN CULTURAL HERITAGE




                                                                                               83
