Distance from retaining wall to house wall
We are working on plans for a new house in Western Wisconsin, and have a sloping site. We are working on a plan to have all critical living spaces on the lower floor to make it easier as we age. My original thought was to have the lower level as a walk out basement, but insulating and waterproofing a below grade wall seems expensive and difficult. There is about a 6′ to 8′ difference in elevation in 30 feet of slope, so a retaining wall behind the house could be 6′ to 10 feet in height. It would probably be stepped in 2 or 3 tiers as necessary–space isn’t a problem.
My concern is the minimum distance that makes sense from the back of the house to the base of the retaining wall. I am assuming that at least 10′ to 15′ would be good so that the grade at the house can slope back to the wall to ensure drainage away from the house.
Any suggestions or concerns that I am overlooking?
Thanks!
Jim in western Wisconsin
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Replies
Jim,
The greater the distance, the better. Certainly you want to be able to create a swale at the base of the retaining wall, and that swale needs to be drained. The grade from your foundation to the swale must be adequate to allow rain to drain away from your house.
I've seen a few retaining walls too close to buildings in my day. You want to be able to drive a truck or a tractor all the way around the house -- that will simplify future maintenance and repairs. You also want to be able to set ladders that can reach the eaves of the roof.
Another consideration is dampness. You want enough space for it to drain, as Martin says, but also you want any accumulated water to be able to dry out. If the wall is on the north side, there could be all sorts of problems. The house will shade the area between the house and wall and it'll never dry unless there's considerable space between them. Of course snow would also accumulate and take a long time to melt. You sure don't want a primary entrance there either.
Pushing dirt around is relatively cheap. I'd ask the excavator if it is possible to avoid the issue entirely by making the area around the house flat, even if it means moving a lot of material. That's what we did at my house, although the slope wasn't as steep.