Masonry Lintel Bearing Length (TMS 402)

Effective span = clear span + depth capped at the support centers (2.3.3.4.1), reaction from the UDL, required bearing = reaction / (allowable stress x width), governed by the 4-in code minimum (2.3.3.4.3). For an ordinary 6-ft lintel the stress check wants 0.44 in and the code minimum governs at 4 - which is exactly why a stress calculation alone misleads. The allowable stress is YOUR input: published sources disagree on the coefficient, so no number is shipped.

Effective span = min(clear span + depth, distance between support centers); reaction = udl x eff span / 2; required bearing length = reaction / (allowable bearing stress x bearing width); governing = max(required, 4 in).

TMS 402 (MSJC) lintel provisions by section number: 2.3.3.4.1 effective span (clear span plus depth, not more than the distance between support centers) and 2.3.3.4.3 end bearing not less than 4 in.

The two provisions used here are reproduced with their MSJC citations in the freely published CMHA/NCMA concrete-masonry lintel design manual; TMS 402 itself is available through The Masonry Society.

Estimate. AHJ and licensed professional govern.

Field names used by the API: clear_span_ft, lintel_depth_in, udl_plf, bearing_width_in, allowable_bearing_psi, eff_span_ft, reaction_lb, required_area_in2, required_bearing_in, governing_bearing_in

• Effective span clear span plus member depth, capped at the distance between support centersTMS 402 (MSJC) 2.3.3.4.1
• Minimum bearing not less than 4 in, and it usually governs over the stress checkTMS 402 (MSJC) 2.3.3.4.3
• Allowable stress entered no coefficient shipped - secondary sources disagree, so the designer supplies the valueuser input from the governing code edition