Hi. I’m having a loft conversion and retiling the roof. Structure is up including dormer but there are delays in getting roof materials to retire the front roof. Builder wants to press on a do boarding insulation and plastering whilst waiting for roofing materials. Roof has holes in it from velux instalment but is covered with a tarp. They assure me this is fine. I’m concerned that it should all be properly weathertight before proceeding with boarding and plastering. Really welcome advice. Should I tell them to get the roof done first?