Footing 12" below undisturbed ground surface

[jtwright4216]

Hey guys,

IBC chapter 1809.4 Depth and Width of footings states:

The minimum depth of footings below the undisturbed ground surface shall be 12 inches. Where applicable, the requirements of Sections 1809.5 shall also be satisfied. The minimum width of footings shall be 12 inches.

And 1809.5 is for frost protection. My interpretation of this statement is to provide protection and prevent erosion for the footing on the exterior side in areas that don't have frost depth requirements. Such as California. Not a general requirement for ALL footings including interior pony walls and pad footings. The key word seems to be "undisturbed" soil. Building officials and other engineers are interpreting this as the crawl space finished floor as well. I don't agree because I don't see any benefit of digging down another 12" to put a interior continuous footing. The IRC (403) states it correct by saying 'Exterior' footings for the same statement.

Anyone else have an different interpretation of this?

 

[dik]

I used to require that the last 6" be hand excavated... now require the founding material be reviewed by a competent geotekkie... As long as the founding material is suitable, I really don't care what the depth is (except as noted for frost heave).

Dik