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Concrete Compressive Strength for Walls Per R404.1.3
April 26, 2017
9:51 am
New Member
Forum Posts: 1
Member Since:
March 2, 2017
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My question is related to the proper usage of the prescriptive code tables for a 48" tall crawlspace wall.  There is potentially 40" of unbalanced fill because of exterior grade being taller than the crawlspace grade.  Also, the EFP that we typically see in our area is 65 psf/ft of depth.  The tables in R404.1 all cap out at an EFP of 60psf/ft.  Since we are beyond the limits of the table, the way I've interpreted that in the past would be that we fall back out to a non-prescriptive wall via ACI332 or ACI318.  However, the f'c values differ in these codes based on the exposure class.  The ACI332 is closer to what the IRC shows, but it requires that the top and bottom of the wall have continuous support in order to qualify.  We do not consider the floor diaphragm a support for the top of the wall.  As such, we have then been kicked out to ACI318 for design.  However, the f'c requirements for similar exposure are more restrictive than the residential code (3500psi vs 3000 psi).  Would it prudent to argue that the residential code's f'c requirements would still be applicable for the design portion of the wall?