Is it a bad idea to form the basement slab and footers and pour all at once? 2000 s.f basement with one side at grade (and deep frost footers) It sure seems nice to have a flat, clean surface to work on from the start…what are the issues I might be missing? Has anyone done this with a basement? Around here footers, walls, then slab is the usual sequence.
This way, when I form and pour, I can brace the forms from the exterior, and use scaffolding on wheels inside for the pump and vibrate guys. Plus I pick up 4″ headroom which I can use!
The only head scratcher is how to turn up insulation at the edges for a thermal break (radiant tubes in slab) which I can address creatively. Maybe I pour the footer, place foam, switch to 6 bag mix, then pour the slab. The foam break will also function as an expansion joint.
In terms of waterproofing, I am thinking of troweling a step in where the inside edges of the forms meet, and a slight incline past where the outside edges meet.
Here is a ROUGH drawing – not to scale!
Edited 4/14/2005 8:38 pm ET by Brian
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I recently built an ICF wall on top of a conventional thickened edge slab. I left the slab edge form in place to support the ICF forms and built up from there so the concrete slab edge lined up with the outside of the wall concrete.
After the wall pour, I removed the slab forms, added insulation and waterproofing membrane.
It was a pain. It added to the total time on the job because the slab couldn't be poured at the same time sopmething else was going on but had to be done first. We braced from the inside by laying rough 2 x 10's all over the slab and fastening the bracing to them. It felt pretty fragile at times as well as being a nuisance to move arouind in. I wouldn't do it again if I could avoid it.
Ron