Can you add a screen/sun room and deck to a slab on grade?
Building a 26x32 cabin on a heated slab on grade and want to add a 12x12 extension as a screened room. The plan is to have the extension and roof attached to the cabin. Can I extend the concrete slab for this extension and not have it heated? Concerned that the concrete will fail on the extension as the heated slab will float differently then the non-heated section (Northern Canada build with cold winters). Also, when adding a deck to slab on grade building, does it have to ve floating and detached from the building? Thanks!
Yes, you can build a slab on grade with a radiant heated floor and have an attached unheated screen porch on the same slab, you just need to be sure to insulate between the heated and unheated portions. This is not the easiest thing to accomplish with a hand made slab but a company that supplies prefab slab on grade kits (Legalett) can easily provide that, see more here –
Slab-on-Grade Raft Foundation Insulation Detail, Prefab ICF Form Kits
There is reason to be concerned that the slabs would settle and shift differently and potentially lead to structural failure if it isn’t done right, so you would really want it designed by a geotechnical soils engineer that specializes in this. I know that Legalett does that, they provide stamped engineering drawings and installation instructions, and give that it is a ‘raft slab’, despite being thermally separated to prevent heat loss, when they design it the entire slab reacts as a single unit so you would not experience any differential settlement. They supply slab on grade form kits for the US and Canada, to most locations at least. Where in Northern Canada are you building?
Thanks for the quick response Mike an my apologies for the delay in responding. I'm building in western Quebec and have the size and model almost confirmed but again struggling with the options for the extenstion and deck. I keep searching the internet hoping to see information (video or pictures) of someone who has done it but no luck so far. Thanks! Pierre