Hi again, Got the old house completely gutted and chuffed with condition of walls and joists/rafters. Demolished outbuilding and starting to organise founds for new (small extension) build. However after quoting Walls construction on drawing (having obtained Planning and Building Regs Approval) as...100mm concrete block outer leaf + 50mm cavity + 65mm celotex +inner leaf of 115mm celcon blockwork.....I've been informed that because it's a kitchen then inner leaf should be concrete blockwork because Thermalite blocks (Celcon) is/are a nightmare for fixing anything heavy to it -like heavy kitchen units. Can anyone advise please.