Noise from GRP flat roof

[catlad]

Well another alternative to try before you start again is to buy a few hundred 10" screws and drill through your decking to find the joists ( which is how it should have been done in the first place) you will then need to do the GRP again.
This will only have some effect if you can locate the joists.

 

[KMirza]

Thanks Catlad. What about using chipping? Would that work?

 

[catlad]

Stone chippings I presume? It will have some effect I,d say if your roof can take the weight.

 

[Mick Smith]

Bit of an update, I have cut an expanding joint across the complete roof from side to side approx 30mm wide. The roof is now basically two sections, 8mtrs by 4mtrs each. I haven't got round to doing anything else such as adding additional screws across the whole area due to ongoing renovations internally however the noises are getting worse. Some days it's like firework night some of the bangs sounding like a shotgun going off.

Just wondering is it the OSB making the noises or is it the GRP when its expanding and contracting as i'm finding it very hard to understand how little movement can make such loud bangs?

 

[KMirza]

Mick Smith this is the conversation l just had with the builder. Is it the OSB or the GRP?
Can you recall what was the weather/roof etc on the day?
We just put shingles today to see if it works?

 

[Dr_D]

Add another to the list...

Had a ~35m extension built this summer with a GRP flat roof. Every time the sun shines it creaks and bangs, sometimes very loudly when the sun is strong.

We have a warm deck -> no insulation between joists, T&G OSB boards with 100mm insulation sandwiched inbetween then resin and topcoat on top.

IMO it is the GRP that makes the noise. It happens almost instantly when the sun hits it. Desperately following this forum to hear if anyone finds a solution.

If not, would it be a big job to remove the GRP and replace with EPDM sheet? The whole house has just been decorated, so don't want to start all over again.

 

[Dr_D]

I just spoke to the roofing system manufacturer (Cure it).

They said creaking and banging is most often caused by using too few fixings. The boards should be fixed every 200mm to a depth of at least 40mm into the joists. Will be taking this up with the installer to find out what he did. Given the rest of his work it's almost certain he cut corners on the number of fixings.

 

[Mick Smith]

I just spoke to the roofing system manufacturer (Cure it).

They said creaking and banging is most often caused by using too few fixings. The boards should be fixed every 200mm to a depth of at least 40mm into the joists. Will be taking this up with the installer to find out what he did. Given the rest of his work it's almost certain he cut corners on the number of fixings.

How did you get on with the installer?

I added a number of additional fixings to part of the roof to see if that improved it. Still getting a few creaks from the area even in this cold weather so not convinced. When I walk on the areas I fixed they crack like hell. I'm now resigned to the fact that the flexing in between the screws from joist to joist cannot be overcome so probably going to remove the GRP in the summer and replace with rubber.

 

[Dr_D]

He said he used the right amount of fixings. Now it's cold when there's a frost on the roof you can see the location of the fixings and there do appear to be quite a lot, probably not every 200mm though. As you mentioned though, obviously they can't fix the roof between the joists.

In this cold weather the noise is not as noticeable, but it still creaks occasionally when the sun shines.

Like you I will probably have it replaced with a EPDM rubber covering in the summer.

 

[David_S]

Another home owner here with the same problems.

We had a GRP roof installed in September 19. Warm deck construction. The roof makes very loud cracking and banging noises whenever there is the slightest change in external temperature. The builder/carpenter have never heard of this issue before and the roof installer assumes this is just the roof "settling in" and probably caused by the celotex insulation underneath.

Having read through this thread it seems as if there is no common fix to the problem let alone an well understood cause. Without doubt it is temperature change causing thermal expansion and contraction, but to what exactly? What other fix is there other to strip the roof and start again either with additional fixings or a different membrane? And then who is actually accountable for the cost of this? I don't think for a minute the carpenter or roofer will accept liability especially as the issue is not well understood.

My thoughts to remedy this currently are the addition of an expensive sedum roof or to re-roof with epdm.

Following this with interest to see if there are any developments with others roof's.

 

[Dr_D]

Without doubt it is temperature change causing thermal expansion and contraction, but to what exactly?

That is the question. And no one really knows, it seems.

My plan for the spring/summer is to get a flat roof specialist to come and have a look (builder did the roof himself). There are two possible problems from my lay point of view.

1: I don't think there is insulation between the joists at the end, i.e. where the fascia is. This probably means the warm deck contruction is wrong and cold air is getting in underneath the insulation. Possibly this could cause expansion/contraction of the insulation?

2: You can see the edges of the OSB boards on my roof. This may be because they are too close together - no expansion gap. Also because I can see them I know they run parallel with the roof joists in many places. I'm pretty sure they should be at right angles to the joists. This might be why they don't have enough fixings. At right angles they would have fixings every 400mm or so, everywhere there is a joist. But parallel the fixings will all run along the same joist.

Based on what a specialist roofer says I will go back to the builder and say I'm having this roof replaced after 5 months because it was done wrong and ask him to contribute to the costs. No way would I let him touch it again. If he refuses to help out I'll change my review on checkatrade to say what happend and how he did it wrong and left me to deal with it.

It's the only leverage I have now, not much but he was desperate for me to do a review so it might have some weight.

 

[alex henebury]

I too have a grp banging roof!! Definitely heat related , most specifically sunshine.
Its a warm roof and I noticed ( as its not plasterboard yet) that the firrings aren't as tight to the joists as perhaps they could be. Small gaps I can get a thin feeler gauge through in places.I wonder if the decking fixed through the celotex to the ply underneath , and this to the firings is all secure but as the sun heats it and it moves the whole thing ( decking , celotex,ply , firings - one giant structure) is pulling off the 8x2 joists the firrings are perhaps not best fixed to.
I think they used nails. as a carpenter I would have used screws.
Any thoughts on this?
Has anyone had any luck curing this?
I als wondered of the plant based roof coverings mentioned helped ( as they would act as barrier between the roff top and the sunshine

 

[alex henebury]

I just spoke to the roofing system manufacturer (Cure it).

They said creaking and banging is most often caused by using too few fixings. The boards should be fixed every 200mm to a depth of at least 40mm into the joists. Will be taking this up with the installer to find out what he did. Given the rest of his work it's almost certain he cut corners on the number of fixings.

I just posted something but looking at your comments they might be the answer. If the boards should be fixed 40mm into the joists , does this mean presumably 40mm into the main joists , after going through the firrings?

 

[alex henebury]

anyone...

 

[noseall]

anyone...

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