Load Bearing Capability

An assessment of the loading carried by a lintel can be made by a triangle method, as given in BS 5977: Part 1 (European and British Standard specification for lintels). The 45 degree triangle, of base equal to the span of the lintel, represents the load the lintel must bear.

BS5977: Part 1 calculates that a lintel should resist a load of 1.46kN (kiloNewtons) at a 1.8 metre span of exterior brickwork with a serviceability load of span/200. The largest, 2.7 metre wide No More Props resisted a load of 20kN in test, giving a factor of safety in excess of 13 times the BS Standard’s requirement. See below for full load bearing details of all sizes.

BS 5977: Part 1 states that the laod a lintel has to bear can be represented by a 45 degree triangle of base equal to the lintel length. The remainder of the load above is dispersed through the wall of to the sides of the lintel.

Uniformly Distributed Load Test

Unit Size (mm)	Span (mm)	Maximum Load at Span Span/200 KN*	Load Required by BS 5977 (assuming brick & outer leaf) KN*	Maximum Load at Span Span/200 kg	Load Required by BS 5977 (assuming brick & outer leaf) kg
1900	1000	31.1	0.45	3141	45
2400	1500	24.2	1.02	2445	103
2700	1800	20.1	1.46	2028	147
* 10 kN is equal to 1 metric ton.

Ultimate Load Test

Failure Load (kN)	Failure Load (kg)	Central Deflection of Lintel at Failure Span/200 mm	Mode of Failure
73.43	7424	1.1	Diagonal cracking of the wall at the underside of the bearers and above the centre span of the lintel