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Fibreglass or EPDM flat roof?

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Doug71

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My mothers house needs a new flat roof on a kitchen/bathroom extension, the existing is traditional felt, probably done 20 years ago. The area is roughly 4.5m x 3.5m, it is attached to the rest of the building on 2 sides.

My trusted roofer does Fibreglass and has quoted me for this.

I hear many people singing the praises of EPDM but I know nothing about it?

Is one better than the other, educate me please 🧐

Many thanks, Doug
 

HappyHacker

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I have never had a fibreglass roof. I do however have three EDPM flat roofs, probably about 15 years old, have not had any problems and they look fine and I would use it agin if I needed to do a flat roof. I have heard of people having problems with FG roofs but I think it was down to poor application rather than an underlying issue with fibre glass system. The people who did my roofs had the EDPM made up in a factory so it was supplied to fit the roof, so there was no jointing on site.
 

RobinBHM

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both work well.......but:

both dont work well if badly done....

GRP is very rigid, it must be installed to avoid issues with expansion and contractions. generally that means fitting to the roof only, an upstand where it meets the house, the roof and upstand are fibreglassed, with nothing touching the house and then lead flashing dressed down.

also cheaper kits dont use proper roof resin which has a bit more flexibility.

GRP done badly can make awful banging noises as it heats up from solar gain


EPDM: great material, let down somewhat because DIYers and cowboys can get the materials
the jointing and detailing at abutments and corners is what lets it down if not done by a pro.
I fitted it on my cabin -its great, the only thing is on a really sunny day I get a whiff of hot rubber.

it doesnt matter if the EPDM comes in one piece or is joined on site -it can be glued very well on site, although as the roof is not too large it could be order in one piece. Even if it is ordered in one piece it may have a seam in it.

I took down a shed recently that my Dad had reroofed with EPDM 25 years ago -I kept the EPDM sheet as its good enough to be re-used.
 

weekend_woodworker

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I have no experience of fibreglass rooves but I know my brother in law had lots of problems with his that was installed by a builder.
Last weekend I replaced my parent in laws porch roof as the felt was leaking. I replaced it with an EDPM roof from rubber4roofs. I watched their videos and replaced the chipboard deck with an new OSB one. It took me two days to do. Laying the rubber is straightforward. The time consuming bits are clearing the old roof and laying the deck and then finishing off the corners.
I am told it is nice and dry and would certainly recommend it to others.
 

Fitzroy

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It’s all in the details as others have said. A flat roof with only external corners is easy, it’s the upstands, internal corners, hidden gutter pipe, roof window etc that act as leak points and scupper the job. I’d check the roofer has experience of a similarly detailed roof in the same roofing system and recommendations from that client.

F.
 

Suffolkboy

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I have some experience with glassfibre in boatbuilding and have done a few roofs with it.

I have also repaired roofs where the glass was poorly laid by numptys.

Issues like getting moisture on the glass mat, not mixing the resin and catalyst properly. Not finishing with proper gelcoat, just general incompetence/laziness.

Done right Fibreglass is a fantastic material and will last and last. Like anything though if it is poorly applied it won't work.

I'm not a roofer nor do I have any experience of EDPM so not sure how valid my post is but I wouldn't hesitate to have a glass roof IF I knew it would get laid right.
 

NikNak

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This thread caught my eye....

We're also about to have a flat roof to the front of our house redone as it could 'do with it', approx 28sqmtrs. Currently (proper) hot melt tar ashfelt as done by the builder when the house was built some 30 odd yrs ago. No blisters but is showing some cracking though.

I looked at the 3(?) alternative methods of repair.... traditional torch on felt, GRP and EDPM. And we've decided to go the torch on felt route. Mainly due to cost, not that that is an issue, but more because we won't be here to see the 'life' of the new roof expire.

I worked with GRP for over 30yrs, mainly building the tooling for the wind turbine blades, and then teaching the infusion method of building the blades. And having checked out several sites that would sell you a 'kit' to redo your roof i can tell you theres no way i would put down just a 450g mat, or even a 600g if you pay extra. In my early days i used to build motorcycle fairings, Pantera, and even they were built using more matting that what they're supplying to do your roof. As others have already mentioned it IS rigid. Done well it could be good. Done badly.... good luck....

Hope this helps...


Nick
 
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