What material is best for a flat roof?

I am looking to replace my 55m2 torched-on-felt flat roof and would like to know if anyone has installed any one of these: mastic asphalt, GRP and Fibreglass, PVC single-ply membrane, TPO single-ply membrane (Thermoplastic Polyolefin) and EPDM single-ply membrane (Elastometric membranes) and what you have to say about it. I have read about the pros and cons, but would like to get the homeowner's perspective, and also what they paid. I have been quoted €14800 for a fibreglass roof and €10,000 for mineral roofing felt only (plywood already in situ). The cost seems OTT but perhaps this is the going rate? Any information you can share which will help me make an informed choice, will be greatly appreciated.

I have a converted garage (not as big as your area) with flat roof and we went with single-ply membrane. No issues with it so far after 4 years. One tiny bit where there was a join started to leak a little but company came back & sorted it out - at the joins they have to be careful for obvious reasons. We have the membrane and also a large rooflight in the middle of the roof. I'm not sure of the exact size but think a smallish garage with a bit added to the back making it longer. Just before Covid, this cost us €2500 for the membrane & fitting.

Is there a world you can add a slope?

Cooler_box said:

Any information you can share which will help me make an informed choice, will be greatly appreciated.

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I have a concrete 25 Sqm flat roof to the side of the house. I had the old felt removed and two new layers of torch on felt supplied, fitted and flashed properly with lead into the gable wall and around the chimney stack. Cost a few months ago was €4.5k plus vat. Two other prices were similar, another was €8k plus vat and these all wanted to leave existing felt in place, which I didn't want.

We had a fibreglass roof installed about 6 years ago, it was great for maybe two years then it all started to delaminate from the ply below. The more it did this it started to crack and leak and in the end we had to get torch on felt installed on top of it.

You really have to be careful with installers and with a torch on felt roof, it's obvious normally where it's gone wrong and you'll have no hassle getting someone to repair it.

Alkers86 said:

We had a fibreglass roof installed about 6 years ago, it was great for maybe two years then it all started to delaminate from the ply below. The more it did this it started to crack and leak and in the end we had to get torch on felt installed on top of it.

You really have to be careful with installers and with a torch on felt roof, it's obvious normally where it's gone wrong and you'll have no hassle getting someone to repair it.

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Thank you for taking time to leave a comment. I agree that one has to be cautious, but it is extremely difficult to know who you are dealing with. It’s easy for anyone to set up a website and have a portfolio of completed projects and 5 star reviews but how does one verify all of it is genuine? Is sight of their insurance and that they are registered on Solocheck enough?
I asked one Contractor to show me their insurance and another for references. None obliged and I haven’t heard back since.

Alkers86 said:

We had a fibreglass roof installed about 6 years ago, it was great for maybe two years then it all started to delaminate from the ply below. The more it did this it started to crack and leak and in the end we had to get torch on felt installed on top of it.

You really have to be careful with installers and with a torch on felt roof, it's obvious normally where it's gone wrong and you'll have no hassle getting someone to repair it.

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Thank you for your comment. GRP was an option I had considered until I looked into it. It seems there are different fibreglass materials out there, and they are not all equal!

Des Pondent said:

I have a concrete 25 Sqm flat roof to the side of the house. I had the old felt removed and two new layers of torch on felt supplied, fitted and flashed properly with lead into the gable wall and around the chimney stack. Cost a few months ago was €4.5k plus vat. Two other prices were similar, another was €8k plus vat and these all wanted to leave existing felt in place, which I didn't want.

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Thanks for leaving a comment. Most helpful. Do you mind if I ask who did your roof?

myate said:

I have a converted garage (not as big as your area) with flat roof and we went with single-ply membrane. No issues with it so far after 4 years. One tiny bit where there was a join started to leak a little but company came back & sorted it out - at the joins they have to be careful for obvious reasons. We have the membrane and also a large rooflight in the middle of the roof. I'm not sure of the exact size but think a smallish garage with a bit added to the back making it longer. Just before Covid, this cost us €2500 for the membrane & fitting.

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Thank you for leaving a comment. Mind me asking which Contractor you used? PM me as I’m not sure you’re allowed to mention it in a conversation?

Alkers86 said:

We had a fibreglass roof installed about 6 years ago, it was great for maybe two years then it all started to delaminate from the ply below. The more it did this it started to crack and leak and in the end we had to get torch on felt installed on top of it.

You really have to be careful with installers and with a torch on felt roof, it's obvious normally where it's gone wrong and you'll have no hassle getting someone to repair it.

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Fibreglass roof installed 9 years ago. It is still going as good as on day 1.
However, it is not exposed to the elements but 1) has been painted 2) edges are covered with zink finishing, and 3) on top of the roof, we put sedum. No issues.

newirishman said:

Fibreglass roof installed 9 years ago. It is still going as good as on day 1.
However, it is not exposed to the elements but 1) has been painted 2) edges are covered with zink finishing, and 3) on top of the roof, we put sedum. No issues.

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Thanks for your comment. The sedum on the roof sounds delightful and very eco friendly too. Not all fibreglass roofs are created equally. It all depends on the 'type' of fibreglass and who's installing it. If its lasted 9 years and you're still happy, I guess you were fortunate in the contractor you chose. Would you mind sharing their details and (if you don't mind) what it cost too (PM me if you wish).