I'm building a deck over a walkout basement. I want to put a concrete patio below. Can I dig the footers (3 total) to depth of 30" below the frost line and then do a monolithic pore of the concrete for footers and slab? I plan to use simpson post base over the footer location imbedded in the concrete. The other option is to use the concrete tubes and do the footers/concrete piers first and then poor the slab around, but trying to save time.
Thanks
Best Answer
Since you’re not making your concrete patio as deep as the footers, your patio will be subject to frost heaving. This means that if you mechanically connect (e.g. build in a single pour) footers and patio, you’ll make your footers subject to frost heaving as well, even though they reach below the frost line.
I believe heaving of the patio might be mitigated if you pour it over a bed of crushed stone, like basement and garage slabs are done, but I don’t have experience with this.
Side note: you should use concrete tube forms regardless, as they will make your footers relatively smooth, making it much harder for anything subject to heaving to “catch” them and jack them up.