Proper way to pour a basement slab?

mebke33August 28, 2012

I also posted this on the "building a home" page. We are trying to decide on a sub for flatwork in our ranch style home with a walk-out basement. We have several differing opinions on how the the basement slab should be poured. One states that the slab should be in direct contact with the footings. The second states that the slab should float on a bed of gravel and not directly contact the footings. Is there a standard technique or is this just individual preference? Does anyone have any experiences, either good or bad, for either technique? Thanks.

Thank you for reporting this comment. Undo

Depends on the weight bearing ability of the soil under the footers and slab.

    Bookmark   September 1, 2012 at 4:04PM
Thank you for reporting this comment. Undo

For pouring the basement floor, one must take care to prevent future cracking. Unlike pouring an open slab of concrete, the basement floor has the unique aspect of sitting within vertical concrete walls so some special techniques are taken to smooth the concrete from only one side.

    Bookmark   September 12, 2012 at 3:07AM
Thank you for reporting this comment. Undo

compacted sand or gravel to be brought up to the level of the footing, then 10 mil vapour barrier/poly to cover entire floor area from wall to wall with all cuts or holes in the poly sealed.
Pour slab 4" thick on top of the footings. THis is the standard procedure and widely accepted as the proper way to lay concrete. The only guarantee with concrete is that it will turn gray and crack. you can try to cut in control joints but sometimes the floor doesns crack where you want it to anyway.


    Bookmark   October 28, 2012 at 9:36PM
Thank you for reporting this comment. Undo

Our full size basement has a concrete floor poured, with steel footings that hold the 2000 sq ft rancher house. All footings have contact with concrete but you can see that the floor was poured first - while footings had collars around them. Then the footings got the concrete too. So there is a circle line in the concrete around the footings. This is a 5 year old and no new cracks anywhere. I hope this makes sense, unless I can find pictures.

    Bookmark   October 30, 2012 at 11:57AM
Sign Up to comment
More Discussions
Flooring System over a basement
In my current house we used 16-18" deep floor...
want to finish basement but very humid...
Have an unfinished basement. House built 2012. During...
Str'l Wood Floor + CrwlSpace vs Concrete Slab
Hello, We were discussing our plans with a builder...
water leakage under drywall in basement
We just bought a new home. Originally built in 1907,...
Electrician on his way...
OK, we are in the beginning stages of wiring - and...
© 2015 Houzz Inc. Houzz® The new way to design your home™