• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

American Wood Council Calculators and Tools


Chief Cook & Bottlewasher
Oct 16, 2009
Palm Beach County Florida
You might find this link extremely useful:

According to the AWC:

A 2x8 treated southern pine used as a floor joist can span 12'11" at 16"o.c. with a live load of 40psf and a dead load of 10psf in wet conditions. They also claim that this span only requires 5/8" of bearing on each end. This would be in compliance with a deflection limit of 1/360.

How does this compare with the code requirements of the IRC for the same application?


Registered User
Oct 20, 2022
Berkeley, CA
The part that surprises me is the 5/8” bearing.
5/8" bearing at each end, and 1-1/2" member width = 1-7/8 in^2 of total bearing area.

50 psf total load * 16"/12" tributary width * 12' 11" span = 861 lbs total load.

861 lbs / 1-7/8 in^2 = 460 psi allowable compression load perpendicular to the grain, after all the design factors have been applied.

That's in the expected ballpark, depending on species the reference design value (before design factors have been applied) varies from 300 to 900 psi.

Cheers, Wayne