ᐅ Basement slab poured, now awaiting cold days with frost

Pictures and the weather report are sufficient for this. The slab is already poured, so the problem is already set in stone. If there are serious doubts about the professional quality of the work, you need to consult an expert.

Informing the general contractor (GC) that you are concerned about the workmanship is a waste of time. It also does not help in court... In court, what matters is whether the work is done properly or not. And that is assessed by an expert witness.

xMisterDx schrieb:

If he thought it would be problematic, he wouldn’t do the work.

That assumes 1. he is competent enough to identify the mistake and 2. he expects the client to notice the problems.

Here in the forum, there are plenty of examples that can only be explained by incompetence combined with a "no one will notice anyway" attitude.

What good does that do?

A general contractor (GC) is unlikely to say, "Oh yes, good that you told us. We didn’t know you shouldn’t pour the slab during freezing conditions. By the way, since we have you on the line, we had this dimpled membrane with us—should we have installed it under the concrete? And what was all that rebar for? We took it back with us; we’ll build a grill out of it."

If the tradesperson wasn’t confident that they were doing the job properly, they wouldn’t do it… and they certainly wouldn’t admit that the work wasn’t done correctly.

Do you think I would tell a client, "Well, I have absolutely no idea about this, but let’s just start and hope it works out"?

With the appropriate additives, it is possible to pour concrete reliably even at below-freezing temperatures (cement additive, antifreeze agents, etc.), but of course, this does not come for free.

Concrete C25/30 (standard for non-waterproof ground slabs) contains at least 280 kg/m3 of cement. At a thickness of 25 cm (10 inches), the core temperature rises to about 15 degrees Celsius (27°F) above ambient temperature. The core temperature is reached after approximately 1–2 days and then decreases by about 5–10 degrees Celsius (9–18°F) per day. Concrete is considered frost-resistant if it remains above 10 degrees Celsius (50°F) for three days.

The vapor barrier is sufficient to retain heat and moisture, and the ground slab generates enough internal heat. In my opinion, there is no reason to be concerned. If you lift the barrier at the edge, you will notice that it is damp underneath but no ice has formed.