ᐅ Concrete slab foundation instead of strip footing?

Hello! I hope you can help me! We are building a single-family house with a garage and no basement, doing a lot of the work ourselves. There is a geological survey of the construction access road (about 10m (33 feet) from our plot). The soil is soft clay, so our architect and structural engineer believe that a strip foundation with a slab on grade would not be stable. Instead, they recommend at least 50 cm (20 inches) of compacted gravel using a plate compactor, followed by a 30 cm (12 inches) thick concrete slab on top. I’m not feeling confident about this. What do you think? Can I rely on that? And what about the frost protection edge? How should I insulate it?

Thank you very much in advance!

Hello Oleg,
as a layperson, you can only rely on what the professional says. You can always get a second opinion if you’re unsure. Why are you choosing not to include a basement? Is it cheaper, or is there another reason?

I probably have no choice but to trust the professional. A basement is not an option due to cost reasons and because the groundwater level is very high.

Hello,
we also have a very high groundwater level, so we built a waterproof basement tank. We needed the basement because otherwise we had no place to store our belongings. Additionally, we have a sauna, which we would not have been able to accommodate otherwise.

Hi,
I’m not very experienced with this either, but the idea of having gravel under the house sounds good. It’s definitely important to ensure proper water drainage. You can definitely consult a second expert; no one will mind.

Hmm... that's a complex question, but I believe that in your case, the quality of the soil plays a major role. Only an expert can really assess that.