Affordable backfill without sacrificing drainage?
My upslope lot results in one wall of the first floor performing as a retaining wall, with retaining walls extending some distance beyond on each side. About a 10% upslope behind the retaining wall as well. I will create a swale some distance above the house to direct most water away, but I still want to build in protection from potentially significant water during heavy rains.
Obviously it would be best to backfill with ¾” rock, so any water could drain freely to the drain tile at the bottom of the wall. However, the volume to fill is from 4′ to 6′ deep by 10′ high for some 70′ length, which—if rock—will cost a small fortune. There is however no shortage of soil.
Is there some method whereby I can fill a 1′ trench with rock and the rest with soil? I was thinking of building the two layers up at the same time with a plywood panel between that would have straps attached so the backhoe could pick it up after filling both sides. Labor for this also seems expensive.
Alternatively, will a drainage mat handle bulk water in fairly large volume if necessary?
Note that the house will have 4′ eaves, and 6″ gutters draining to daylight on the other side of the house; I think I’m talking about redundant measures here.
Thanks very much!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part