Y-Tong garage directly on formwork stone - does that work well?

Hello friends,

our garage builder surprised us a bit today. Until now, I knew the method like this: strip foundation, formwork blocks with concrete, concrete slab, masonry.

But he wants strip foundation, fill formwork blocks with concrete, damp proof course, and then Ytong on top. The floor slab is then to be poured from fiber cement concrete with a thickness of 20 cm with edge insulation strips – up to the height of the formwork blocks. For me, this is not really comprehensible. The earth has been excavated and compacted with lime gravel (50 cm).

The 6x9 m garage will have a wooden flat roof. Could you help me? Is this an accepted method? The building expert as well as the surveyor said that structural calculations for a garage are not necessarily required if it is dimensioned sufficiently from the outset. I might agree with that, but like this?

I think that works fine in practice. We have a six by three prefabricated garage, which was simply placed on backfilled shuttering blocks. It works. It holds, no problem.