Solution for crackling fiberglass roof

[johnny2007]

Hi everyone.
My friend had a dormer loft conversion done 3/4 years ago with a fibreglass flat roof.
When temperature changes the roof makes crackling noises and sometimes popping noises.
I went up there and all looks still brand new, no cracks, no bumps, not even moss on it.
In my limited roofing experience I think that they haven't left expansion gaps when installing the osb panels.
He's concerned that it will fail and will need to be completely replaced.
Is this the case or it's just an annoying problem?
Is there a solution to it, apart from redoing the roof?
Thanks

 

[oldbutnotdead]

More often the OSB not fixed solidly to a support structure. Nuisance rather than disaster

 

[johnny2007]

So structurally it's ok.
But is there anything that can be done without opening up the roof?
He would be prepared to take the ceiling down.

 

[oldbutnotdead]

Not much. The popping and groaning is usually the glassed OSB moving relative to the rafters (cos not enough screws, screws too short, board joints not supported fully). Is there insulation between rafters and OSB?

 

[johnny2007]

Not much. The popping and groaning is usually the glassed OSB moving relative to the rafters (cos not enough screws, screws too short, board joints not supported fully). Is there insulation between rafters and OSB?

From what he said the layers are:
Joists,
OSB
Insulation
Osb (apparently they coated this with resin)
Fibreglass 2 layers + top coat

 

[oldbutnotdead]

Does seem to be quite common people getting thermal noise from GRP rooves where the deck is fixed through insulation. My theory (not proved either way) is that insulation hard to the underside of the deck traps heat absorbed by the deck into the deck (rather than radiating into an air gap). Plus you'd need lots of very long screws (200mm ish) to get the advised purchase into the timbers, long screws are expensive.
There are loads of threads on here about noisy grp...

 

[johnny2007]

Ok, thanks.
But as you said, just a nuisance rather than a structural problem.
He said that they sandwiched the insulation between the 2 osb using very long screws into the joists.
Some missed the joists and were visible through the osb before the plasterboard ceiling went on.
The osb on the joists had been secureb prior to insulation, so i guess they did it correctly.

 

[catlad]

Hi Johnny

I have never had this issue, but then I have always glued and screwed my decks.

 

[oldbutnotdead]

Hi Johnny

I have never had this issue, but then I have always glued and screwed my decks.

Quick question (for my curiosity only) have you ever installed grp as his is done (screws through insulation)- i've only done deck direct to rafters/joists, air gap, insulation. No problems with mine either

 

[johnny2007]

Quick question (for my curiosity only) have you ever installed grp as his is done (screws through insulation)- i've only done deck direct to rafters/joists, air gap, insulation. No problems with mine either

Not a roofer, so maybe a silly question, but how would you hold the insulation?

 

[catlad]

If its a warm roof then you have to use min 200mm screws and yes you have to screw through the insulation. I always bond the insulation to the first/sub deck and then glue and screw the top deck.

 

[johnny2007]

I always bond the insulation to the first/sub deck and then glue

The glueing is what's probably missing.