SBMS Posted April 18 Posted April 18 Just noticed this on the architects drawings for flat roof makeup. The firrings have been specified as going on top of the PIR. There’s a comment regarding providing ventilation which doesn’t seem to make sense. Can firrings go above the PIR, or will this cause issues?
SBMS Posted April 18 Author Posted April 18 FYI plywood sub deck is already down as joiner followed architect drawing - so would potentially be rework to put firrings on joists. Should firrings go on top of plywood before PIR? More I look more I think architect has made a mistake?
Mr Punter Posted April 18 Posted April 18 The preference is to keep all the timber on the warm side of the insulation. I would go firrings on the decking, then another support layer of decking, VCL, insulation, waterproofing, sedum system.
SBMS Posted April 18 Author Posted April 18 6 minutes ago, Mr Punter said: The preference is to keep all the timber on the warm side of the insulation. I would go firrings on the decking, then another support layer of decking, VCL, insulation, waterproofing, sedum system. No osb top deck? Can you GRP directly to the top of the insulation?
Mr Punter Posted April 18 Posted April 18 You may need tissue faced insulation but it can be pricey. It may depend on the membrane.
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