Question: Hi Karl, Our City recently prohibited the use of 3 1/2 " curb or stem wall from being used on the exterior load bearing wall of the garage.  We feel the code would require an 8" or possibly a 6" curb if that application is to be used to raise the exterior foundation and allow the slab to be sloped.  Is this correct?

Answer:  No.  The 2012 IRC Section 404.1.5.2  states that the thickness is based on the wall supported.  Also, it states that the minimum actual thickness of a load bearing masonry wall shall be not less than 4 inches nominal or 3 3/8 inches actual thickness.