Backfill and retaining walls

[mayin]

Hello,
What is the maximum height of backfill or grade height on an exterior wall before you have to use conc. block or a poured conc. wall?

I am doing plans for a raised cottage and I don't have a code book at hand right now.

Thank you.

 

[cvg]

I would recommend that you don't place any fill against a wood framed wall, only against concrete or block

 

[cap4000]

The very max. for a "basement wall" I have used for 12 inch CMU block is 10 feet filled solid with rebar as required. Normally after 9 feet go to a concrete wall. The more dead load you have on top of your block wall helps reduce and offset the tension stresses developed in the mortar. Good Luck.

 

[RCEJD]

Bearing in mind the comment by cvg, we have designed walls in excess of 30 feet. Depending on the equivalent fluid pressure and slope of the backfill, calcs usually have the first 4 to 6 feet of CMU, 2 to 6 feet of 12 inch CMU, and then 2 to 6 feet of 16 CMU and then concrete from there. Again, there are many factors this is the typical sequence up to 12 to 18 feet.

There are many inexpensive retaining wall programs on the web, including retainpro that provide the necessary design info and calc quickly and efficiently.

Good luck.