Ask a tradesperson


Grp/fibreglass for walk on roof/terrace/balcony

Im thinking about having a single story extension built and to make best use of the roof and to add a feature I think I'd have the roof as an upstairs garden/terrace/balcony whatever you want to call it lol.
My research tells me GRP/Fibreglass is the best material for this taking everything into consideration.
Now the bit where i need help, so my questions:-
-Do you experts agree GRP is the best choice for the flat roof as described?
-If so which is the best online merchant to buy materials from?
-What is the likely cost of the GRP roof itself which will be 32sqm?

If anyone recommends a different type of system i will certainly look into that too and THANK YOU IN ADVANCE.

4 Answers from MyBuilder Roofers

Best Answer

Going for a GRP roof is definitely a good choice for what you are wanting to achieve, it's important to remember a (650g CSM) is required rather than a (450g CSM) referring to the stranded matting rollered into the resin as being used as a balcony will be subject to more traffic/weight, the best online suppliers of GRP products I would say are Cromar and tough stuff both being quite competitive, it's also a joint less roof system and will be easier to weather the fixing of a balustrade, a rough guide price for that area would be £2500 on a newly boarded roof, another roof system to look into would be EPDM rubber roofs.

Thanks Jason
JL Davis Carpentry


Answered 6th May 2017

We fit loads of GRP roofs now and find them great. You can get a non slip finish as the normal finish is slippy in wet weather. It can be formed round any shapes and upstand sand the finished product is a seamless roof with a 20 year guarantee from the manufacturer the materials can be bought for around £150 for ten meters but you need to install on to 18mm OSB sterling boards in 8x2 tongue and groove boards for best results these are extra on cost and the trims for the edges are around £10-£15 each 3m long so include all of above in price


Answered 5th May 2017

We normally give clients the choice of single-ply or grp, both being durable and long lasting. For the best possible finish, we encourage customers to fit Eurodec promenade tiles. Apart from protecting the roof covering, promenade tiles greatly improve the aesthetic and comfort of the roof terrace.


Answered 9th May 2017

2 layers of 450g matting is what I would strictly use due to heavy foot traffic,

600g matting for a roof, plus with over 80 custom colours to choose from & rubber anti slip granules, I would say grp fibreglass is the best option.

A good Llyods approved resin along with a tar like top coat (gloss) that will give a better finish,look good a few months down the line and gives a thicker lay up ensuring a long life span.

Always go with a specialist ; )


Answered 21st May 2017

Post your job to find high quality tradespeople and get free quotes

Can’t find an answer? Ask a new question

Question Categories