We are building a home on a lot that drops about 7′ over 100′. At the rear of the home we will have around a 7′ stem wall. We will backfill with #57 and do a slab on grade foundation. Is there any reason to waterproof foundation walls without a basement that I can’t think of?
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Some questions:
What is the local climate like?
What is your frost depth (by applicable code)?
How deep to ground water?
Will the home have gutters connected to underground drainage piping?
Will your floor slab butt against the wall or will the slab be cast on top of the wall?
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For an out-building, I wouldn't bother.
For a home (or an out-building that COULD become habitable), I would.
How I would approach it depends on the answers to my questions.
The wall should be reinforced with vertical bars tied to dowels installed in the footing, in addition to 2-3 horizontal bars.
Oklahoma. It get's freezing, but not often. Out of 500' of footer, we did hit ground water in a small 10' section at 24
deep for this lot. Gutters will drain underground to street. Slab will sit on top of wall fully. It is a home not an out-building. We of course will have visqueen under slab, so in my mind it doesn't matter if stem wall get's a bit wet. We also will be using the #57 to backfill which naturally allows for drainage and shouldn't hold water against stem wall.
The problem with casting the slab on top of the foundation is that the subbase material will settle over time. This can result in slab cracks around the perimeter near the wall as the interior of the slab will want to settle with the subbase material.
Crushed stone under the slab will certainly help insure that ground water doesn't accumulate in the soil below the slab - assuming of course that you'll be providing drainage plumbing to daylight inside the foundation walls.
Roof water drainage must be separate from any foundation drainage piping installed.
Reinforcing as I previously mentioned is a must whenever the backfill against the walls is not equal depth on both sides of the wall.
Yes, that it why we decided to go with 57 in hopes of minimal settling and we are doing a post tension slab. Sounds like you are saying we should also do a french drain prior to pouring slab? Would not think that is necessary since there will be a roof not allowing water in the majority of the area, but maybe I am missing something?