This is reassuring. The conditions you describe are similar to mine, and it's the rationale provided by the contractor. Although our frostline is 4ft, I can imagine it doesn't get that deep anymore due to the gradually rising temperatures here (first and last frosts have been 2-4 weeks further in and out for years here.
My only thinking is that whatever is exposed underneath and left over night will then freeze by the next day, depending on the temps here (it really can vary in february)
Thanks again!
