I am new to building additions with basements and to communicating with Breaktime but have a question I need your advice on. The kitchen addition I am building will have a full basement under it consisting of 10 inch poured-in-place concrete walls on a 18 inch wide by 8 inch deep concrete footing. The basement floor will be a 5 inch concrete slab on a 4 inch bed of gravel. My question is how much space should be between the top of the footing and the bottom of the floor slab or does it matter? The floor slab has to be the same elevation as the existing basement floor, but I can move the footing up or down some. I’m still excavating now. Thanks for your help in advance.
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Replies
I seat the slab on the footing but you could separate it with the sand bed or foam insulation
Excellence is its own reward!
If you have a problem in your area with water, as I do, I would lower the footing by four inches, have the crushes stone below the slab go over the top of the footing, and leave a space of 3/4" between the walls and the slab. This works the same as an expansion joint, and gives room for water to run off.
You have to install a sump pump to get rid of the water. I put a high quality pump in the bottom of the hole, and install a second pump on a block so that it is 8" higher. The second pump is AC operable, but with a battery backup, in case you lose power during a storm.When all else fails, use duct tape!