Footing Height
Trying to find the max height *above grade* for a monolithic slab-on-grade footing?
After perusing the IRC and web I have only run into the minimums for depth and width for footings (12×12″ below grade, with 4″ min above). The only thing close is from WA State Code (where I am building) but seems to pertain to stem wall foundations:
WAC 246-359-180 Concrete footings and foundations for wood framed construction.
(4) Concrete foundations must be a minimum of six inches thick, be reinforced with a minimum of one continuous horizontal No. 4 rebar within twelve inches from the top, and one continuous horizontal No. 4 rebar near mid-height, be reinforced vertically with No. 4 at forty-eight inches on center, extend at least six inches above the finished grade, and have a total height of not greater than forty-eight inches.
I am building on a 10-11% slope and hoping to extend the down-slope footing higher above grade to get out of pouring a retaining wall on the upslope side of the house (and instead build a couple of <2′ rockeries about 10′ apart). Any answers or suggestions much appreciated.
Cheers,
Kevin B
Salish Sea – 4c
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
I think at a certain point you stop having a footing and start having a foundation wall.
We looked into doing a monolithic slab-on-grade but because we have a slight slop, we would either need to build out an area with crushed stone which would be costly.
The other reason is many of the concrete trades in my area aren't familiar with monolithic slab-on-grade since full basement foundation is the norm. In fact one company told me they would not quote or do the work.
For those two reason, we went with a small stem wall with a footing at the base. It seems it will be cheaper and more familiar with the traders around here.
Arnold