Why does the fiberglass roof bang?

Question

A flat GRP fibreglass roofed extension was added to my bungalow about a year ago. 

Occasionally loud bangs occur, usually morning and evening - presumably due to expansion and contraction and I am worried that this might cause damage. 

Should I be concerned?

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Answer

From your description I assume the GRP is of the corrugated pattern.

I think that you are right about the noises being caused by thermal movement. It may be that the builder, with the best of intentions, has secured the roof panels to the frame too tightly, using special fixings comprising a neoprene washer that sits on the crest of a corrugation through which the fixing screw or bolt passes.

Crucially the screw or bolt then passes through a spacer sleeve beneath the panel. You may find that loosening the screws very slightly reduces the noise. 

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