So ours was about 9m x 6m and looks to have cost about £5-6k (cost + mgmt fee + vat). That includes prowarm insulation and was 2 layers of T&G chipboard.
That’s just for the underfloor yep
Some of it was around building the floor up and also getting it rock solid (our joists weren’t in great shape and a fair few needed replacing)
So ours was about 9m x 6m and looks to have cost about £5-6k (cost + mgmt fee + vat). That includes prowarm insulation and was 2 layers of T&G chipboard.