Is what my contractor telling me correct?
I have placed a contract for repair and insulation of flat roofs. A fibreglass finish to the roof.
The contractor stated that screws to hold the Xltratherm boards in place would not affects the insulation values also that fibreglass insulation compressed into 75mm rafters by 50mm Xltratherm boards is equivalent to 140mm of Xltratherm boards.
Is this a reasonable statement?
I am trying to discover how much if any degrading in insulating properties occurs when insulation boards are attached to roof beams by screws.