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fibreglass flatroof bubbles

  • 31-08-2021 11:15pm
    Registered Users Posts: 188 ✭✭ declanobrennan

    Hi - I got a single story flat roof extension built there over the summer, with GRP on top. While the final layer has not being applied yet there is concern from an inspection of the roof that the flat roof surface not bonded to the "substrate" - there are bubbles everywhere, particularly during the hotter days of August - and water is collecting in some sections. Basically it seems that the roof film isn't fixed to the roof.

    The builder sold me and my architect on this GRP on the basis that it's a speciality for him and he offered a 25 year warranty.

    He assures me this is the way it's supposed to me and all will be well but my architect is a little worried. Two questions:

    1. does this sound like a problem or is the builder right?
    2. how can I ensure the collateral warranty covers leaks which may occurs - and for 25 years?

    thanks in advance for any helpful replies!



  • Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 16,101 Mod ✭✭✭✭ DOCARCH

    Bubbles definitely do not sound good to me! Any pics?

  • Registered Users Posts: 6,376 ✭✭✭ Alkers

    I would be very concerned. We had a shallow roof replaced with fibreglass and it has been an absolute disaster. The fibreglass has delaminated from the timber underneath and over time this causes it to crack which naturally leads to leaks. Our started leaking within 18 months.

    We've had a nightmare trying to get the builder to repair or replace. Other roofers that we've had look at it have suggested it needs full replacement or possibly to lay felt over it as a remedial measure. I'm led to believe that this is all down to the installer and that appartenly the training course that you need to go on to become an approved installer is only a half day up in ballymount.

  • Moderators, Home & Garden Moderators Posts: 10,101 Mod ✭✭✭✭ BryanF

    Ask product supplier, builder and arch to site - then outline to them that you expect an agreed path to resolution before they leave the meeting..

  • Registered Users Posts: 1,071 ✭✭✭ PMBC

    The builder's warranty only lasts as long as the builder himself, although 25 years would be OK. I think its is that the GRP is guaranteed for 25 years - provided its applied properly and to a background that the manufacturer recommends. There is the rub; like lots of guarantees and insurances, its only when there is a claim that the disclaimers appear.

    In your case, I think its the application of the material. BryanFs suggestion seems good to me or at least talk to the manufacturer of the material - they dont want bad publicity. Hope you get it sorted out to your satisfaction.

  • Registered Users Posts: 188 ✭✭ declanobrennan

    I actually don't have pix but I'll get some and post them up (my own phone camera is not up to much)

    I met the builder at the site today. He is unflappable in his confidence that

    1. it's supposed to be like that and that the layers are connected to the timber below to the degree required and that it won't leak and anyway the final top layer is yet to go on.
    2. the warranty guarantees and leaks but "I promise you it won't leak". Don't get me wrong, I trust the guy and I trust that he believes what he is saying is true - but that's not much use if it turns out to be wrong!

    I'm meeting him and the architect on Monday morning. I don't know about the product supplier - I don't know how I would reach out to them?

    thanks for taking the time to reply lads.

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  • Registered Users Posts: 188 ✭✭ declanobrennan

    The builder did take the time to explain the whole layering process to me today but I'm a lover not a builder and my brain just can't seem to handle construction terms and explanations....

    At one stage he helpfully drew a pic which showed that there is air coming in around from underneath through a lip at the end - he said that this was a cold roof. Which I've read a bit about and seems fine.

    But later he said it was a warm roof. I did ask him to clarify if it is a warm or cold roof and I'm none the wiser from his answer. He said start explaining all the layers again and I glazed over.

    Any pointers to ladybird explanations of flat roof construction and GRP application would be very welcome at this point!

  • Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 16,101 Mod ✭✭✭✭ DOCARCH

    Sounds to me like your builder is trying to cover for the GRP/fibreglass installer!

    Again, to me, bubbles do not sound good, and I use GRP/fibreglass on roofs quite a bit.

    If you have an architect you should be asking them what they think (and to clarify if it's a warm or cold roof).

  • Moderators, Home & Garden Moderators Posts: 10,101 Mod ✭✭✭✭ BryanF

    OP, suggest You tell you arch to set up the meeting. They should organise builder, who should organise manufacturer and installer.

    have you a contract in place?

    have you retention money held back at the moment?

  • Registered Users Posts: 188 ✭✭ declanobrennan

    thanks again for coming back to me on this. I really appreciate it.

    There is a written contract - basically it's just the quote. There is about 40% of the building fees held back.

    DOCARCH the builder is/was the GRP installer. He presents himself as a GRP expert, (I think he even said he carries out training courses in it....not sure if that's a false memory...)

    I will see about getting that arch/builder/manufacturer meeting set up.

  • Registered Users Posts: 188 ✭✭ declanobrennan

    Still no resolution here aside from builder assuring architect and myself that the final two layers are yet to go on. Here are images of the bubbles and of rainwater gathering.

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