3.6 Metres
precast concrete masonry lintels Quality Products for over 80 Years. INTRoDUCTIoN In residential and commercial buildings of concrete masonry, precast lintels are often used to span openings in the walls. The width of the lintel, or the width of the combination of side by side lintels, should equal the width of the supported masonry wythe. Typical concrete compressive strengths for precast lintels range from 2500 to 3500 psi. Lintels are manufactured to an actual height of 7-5/8 inches to coincide with the typical course height of concrete masonry. A modular lintel length should be specified which equals the clear span plus at least two times the lintel height to provide for proper bearing at each end. The width of the lintel, or the width of the combination of side by side lintels, should equal the width of the supported masonry wythe. Typical concrete compressive strengths for precast lintels range from 2500 to 3500 psi. Lintels Introduction Lintels are considered as beams that span over window or door openings. Lintels require special reinforcing details to meet the local code requirements.  The steel for lintels, as a minimum, shouldcomply with ASTM A 36. Steel angle lintels should be atleast 1/4 in. (6 mm) thick with a horizontal leg of at least 31/2 in. (90 mm) for use with nominal 4 in. (100 mm) thickbrick, and 3 in. (75 mm) for use with nominal 3 in. In cases where torsion is pre-sent, the rotation of the lintel can be as important as itsdeflection. The rotation of the lintel should be limited to1/16 in. (1.5 mm) maximum under the combined superim-posed live and dead loads. Deflection criteria, which governs most of the values in Table 2, is based on controlling cracking in masonry supported by precast lintels. Consequently, for lintels supporting non-reinforced masonry, lintel deflection should be limited to 0.00167 times the effective span of the lintel (L/600). The width of the lintel, or the width of the combination of side by side lintels, should equal the width of the supported masonry wythe. Typical concrete compressive strengths for precast lintels range from 2500 to 3500 psi. The steel for lintels, as a minimum, shouldcomply with ASTM A 36. Steel angle lintels should be atleast 1/4 in. (6 mm) thick with a horizontal leg of at least 31/2 in. (90 mm) for use with nominal 4 in. (100 mm) thickbrick, and 3 in. (75 mm) for use with nominal 3 in.  Lintel Length The length of lintel required is calculated by establishing the total widthof the structural opening and adding 150mm (200mm for CXL lintels)end bearing allowance for each end. For example, an 1800mmstructural opening will require a 2100mm lintel (2200mm for CXL). Cavity wall closed eaves lintels 100-115mm Inner Leaf Note: For heavy dutyapplication or lintel in excess of2.7m please refer to the CN71 and CN81 range of lintels onpage 29.Standard lengths are available in 300mm increments. The area of reinforcement for lintels should exceed the minimum reinforcement ratio (pmin = 200/fy) (2) to insure ductile behavior. In addition, the reinforcement ratio should not exceed 75% of the balanced reinforcement ratio (2) (P max = 0.75p b). The width of the lintel, or the width of the combination of side by side lintels, should equal the width of the supported masonry wythe. Typical concrete compressive strengths for precast lintels range from 2500 to 3500 psi. 2. 2.4 Metres. 3. 3.6 Metres. In the case of no 1. (2.7 M wide span) it has the inner leaf of blocks on the flat therefore this lintel will be 225mm wide. In the case of the outer leaf it will be a 100mm wide lintel. All that is over this is approx 5 courses of block and then the roof. Will a prestressed concrete lintel do this job. 
http://www.fendtproducts.com/pdf/products/concrete_masonry_units/precast_concrete_masonry_lintels.pdf http://www.fendtproducts.com/pdf/products/concrete_masonry_units/precast_concrete_masonry_lintels.pdf http://www.amvic-pacific.com/Downloads/Amvic%20Lintel%20Tables.pdf http://www.gobrick.com/portals/25/docs/technical%20notes/tn31b.pdf http://www.fendtproducts.com/pdf/products/concrete_masonry_units/precast_concrete_masonry_lintels.pdf http://www.parkerblock.com/pdf/divisions/brick/contractors/tech-note-31b-structural-steel-lintels.pdf http://catnic.com/assets/downloads/Catnic-Lintel-Brochure-2014.pdf http://www.fendtproducts.com/pdf/products/concrete_masonry_units/precast_concrete_masonry_lintels.pdf http://www.askaboutmoney.com/threads/maximum-length-for-concrete-lintels.59688/
maximum span for lintel