Bearing Length

Bearing lengths reported by RedSpec™ reflect the strength of the RedBuilt™ product listed on the calculation. The strength of the supporting member, however, may control the bearing length. The strength of the supporting member is not considered by RedSpec™. It is the designer's responsibility to do so. Trimmers around window and door openings, used to support headers, typically have a higher bearing capacity than RedLam™ LVL and glulam beams. When RedBuilt™ products are supported in this manner, no adjustment to bearing length is required. This is also true for steel post caps supporting beams. Beams may bear on wall plates which have a compression perpendicular-to-grain value less than the beam. When this occurs, bearing lengths need to be increased. Bearing length adjustments are a function of relative compression perpendicular-to-grain (Fcperp) stresses for RedBuilt™ products and the supporting members. Typical values for Fcperp are listed below:

Beam

​24F-V4 DF GLB Fcperp = 650 psi

RedLam™ LVL Fcperp = 750 psi

Supporting Member

SPF #2 (Spruce-Pine-Fir) Fcperp = 425 psi

SP #2 (Southern Pine) Fcperp = 565 psi

DF #2 (Doug-fir Larch) Fcperp = 625 psi

Note : Values from 2024 NDS® Supplement

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Example:

RedLam™ LVL beam supported on SP #2 plates

RedSpec™ calculated bearing length = 2.2"

Fcperp for RedLam™ LVL = 750 psi

Fcperp for SP #2 plate = 565 psi

Adjusted bearing length = 2.2" x ( 750 psi / 565 psi) = 2.9"

Even though the LVL beam only requires 2.2" of bearing length, the SP #2 plate requires 2.9" of bearing, which governs.