Short Cripple Walls

2308.9.4 Cripple walls. "Foundation cripple walls shall be framed of studs not less in size than the studding above with a minimum length of 14 inches, or shall be framed of solid blocking."

2304.11.2.1 Joists, girders and subfloor. "Where wood joists....are closer than 28 inches....to the exposed ground in crawl spaces....the floor assembly shall be of naturally durable or preservative-treated wood."

2304.11.2.2 Wood supported by exterior foundation walls. "Wood framing members, including wood sheathing, that rest on exterior foundation walls and are less than 8 inches from exposed earth shall be naturally or preservative-treated wood."

What is the upshot of these three codes? If a home is built over a crawlspace it is likely set close to the minimum height above grade or 18" to the bottom of the joists. The foundation will be poured 8" above grade and the cripple studs will certainly be less than 14". Many homes in the San Francisco Bay area fit this style. So this scenario will come up a lot. Note the short cripples in the above photo with plywood showing behind. Exterior shearply will cover the exposed side.

Surprisingly our structural engineer did not include the detail on a recent addition. Furtunately, our inspector interprets solid blocking to include installing shear plywood on the inside, as well as the outside of short cripple studs. I don't know if you can always get away with this approach. I would personally prefer it to solid blocking. The cripple studs allow one to correct the level of the foundation. I have tried "wet-setting" mudsills at the right elevation when the detail ran concrete right up to the bottom of joists but still think cripple walls are better.