How far should concrete masonry lintels bear on the concrete masonry at each jamb?
The bearing length often will depend on the loads on the lintel. If there are concentrated loads within the area above the lintel, the bearing must be long enough to reduce the bearing stress to allowable levels. The structural engineer should determine the bearing length in these cases. In most wall systems where there are no concentrated loads above openings, a rule of thumb often can be used. The Portland Cement Association's
Concrete Masonry Handbook recommends 1 inch of bearing for each foot of clear span. The minimum bearing length, however, should be 6 inches. All decisions regarding bearing lengths should be approved by the structural engineer or architect of record on the project.