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Best roofing material for flat roof

Hi. I'm having a small extension built with a flat roof. What is the best roofing material to use? On the roof will sit a fixed skylight. Thanks in advance.

10 Answers from MyBuilder Roofers

Best Answer

The best roof covering by far is Fibreglass (GRP). It is the only true seamless system and where you have roof lights being installed it is the best option by far.

The second option would be EPDM (rubber roof). This is sold as a seamless system but it's not truly accurate unless to a freestanding garage. Each upstand, although the edges are cut and turned, you have to have these taped - hence - seams. It is quicker to install however and slightly cheaper than GRP.

Then there is your basic felt roof - old roofers still try to sell this with a 20yr guarantee but it normally fails after 10-12 years.

Ensure your roofer/builder uses timber firings on the joists and the best decking is 18mm conditioned OSB T&G (4) NOT plywood.

Then if this is a new roof and has the appropriate planning and BC, you should be installing a warm roof to comply with current regulations.


Drew @ Fibretechs - GRP & EPDM Flat roofing - Gloucestershire


Answered 6th Dec 2015

go for rubber 25 year guarantee but it lasts a good fifty the company that supplies me have just celebrated 50 years since the put there first one down and its still going strong you can have it cut to size the largest they do would cover a football pitch. have a look at there product its called hertalan .


Answered 4th Jan 2016

GRP definitely! Usually comes with a long guarantee


Answered 22nd May 2020

Hi, there are a few different options available. My first choice would be fibreglass, there are different finishes and colours to suite your taste. Fibreglass should only be laid by a professional that has correct training for the specific product supplied. Otherwise any product warranty would be void.
Fibreglass leaves a great finish. Hope this helps. DK


Answered 6th Dec 2015

I would recommend a Cure It roof is a GRP (Glass Reinforced Polyester) fibreglass roofing system. Constructed from a GRP laminate. It has a specially formulated liquid Roofing Resin and Reinforcement Mat. Suitable for complex shapes the material is cut to suit the roof, and no heat is required the Cure It materials come with a 20 year guarantee the laminate is applied over a securely fixed Oriented Strand Board 3 (OSB3) 18mm tongue and groove (T&G) deck, the perimeter is finished with Cure It Trims. Finally the entire roof is coated with topcoat. This finish is available in a wide choice of colours. Installed correctly, a Cure It roof has a life expectancy in excess of 50 years.


Answered 22nd Nov 2019

I would say finreglass


Answered 9th Dec 2019

All roofers have their own preference in materials but at the end of the day what ever product you use weather it be felt, asphalte, rubber, Grp as long as it’s installed by a qualified professional it will be long lasting.

Some materials maybe suit certain roof types for example if you have a small balcony with lots of penetrations your not really going to wana use rubber it would be suited more for asphalt or liquid


Answered 15th Jan 2020

I would fit a (GRP) roof Which is a fibreglass roof My experience that is the best flat roof on the market at the moment but other people would give you other options


Answered 11th Jun 2020

As long as it is installed properly, I would use felt, looks neat and tidy and as long as good quality material is used has a long lifetime.


Answered 4th Feb 2022

Personally I would install a GRP Fibreglass Roofing System. You’ll be looking at a guarantee of 20+ years from most roofers but please ensure that you receive this in writing. GRP roofs are great and low in maintenance and do provide a no worry product. However they are many poor installers of any flat roofing product including fibreglass so make sure you look at reviews of the company’s and their portfolio.


Answered 20th Jun 2022

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