Is GRP a good roofing material?

GRP flat roofing Prose and cons


  • Now easily available in DIY shops
  • Good and strong
  • Tested over many ears to perform
  • Comes in any colour
  • Can be formed into any shape
  • Will hold standing water


  • Very rigid and brittle if laid to thin
  • Has to be laid by experienced people
  • Has to be built up to form a good surface and this takes time and materials
  • Weather and temperature dependable

Other options to consider

  • 3M SD650
  • GacoRoof
  • Kemper

All three are based on the principles of GRP resins and glass fiber but they have been modified to be flexible.

My opinion.

If the GRP roof is laid correctly and to the correct depth they are good roofs however I only ever see well laid GRP roofs when Im down the coats these are normally laid by boat builders and are formed from may layers of GRP,  forming a good strong shell.

If you have lots of money and want a really nice looking roof then GRP is the way to go.


Leaking pipe rots timbers of flat roof

Maintenance of pipes, guttering roofing gullies were all general items that had to be looked at cleaned and maintained on a regular basis thought the year when I first started working on properties.

Unfortunately  with the cutbacks and the lack of intrest some people have in there property these things just dont get maintained.

Have a look at this videio the pipe had been leaking fr some time now the customer has to pay out for repaointing of the walls and a complete new flat roof

The old flat roof will need to be completely removed all the timber joists that are supporting the roof will need striping out and renewing, unfortunately for he customer the insurance company have declined the claim on the bases that this was forceable

We find that the best policy to have when managing a large block of flat is to have a good routine  maintenance schedule. When It come to making claims on the insurance of the block, being able to prove that maintenance was kept up can be an advantage.

Parapet wall and flat roof before and after


Using a liquid roofing system we can encapsulate the parapet walls with ease


Take this old asphalt roof in Wembley, the asphalt has sagged and cracked away from the parapet wall


Cracking is evident and the ceiling below shows water-damage.


The brick parapet wall is  solid construction but the flat roof is built on timber and will settle over time, the asphalt will melt in the summer and go brittle in the winter, with the thermal movement the  cracking occurs.


So after cleaning of the roof taped patches are applied to the cracks before the new roofing system is installed to the roof.



On this roof we are using the GacoRoof a silicon-based liquid roofing materials from the USA . GacoRoof is very flexible and can withstand   the movement described above.


The other interesting factor to all of this is the color of the finished roofing materials GacoRoof  has a white finish and reflects the sun’s heat stopping the  old roof from melting


liquid flat roof gacoroof london 14



EPDM rubber roof inspection

Around five years ago we laid this flat roof using EPDM rubber over tapered insulation, the job was quite complicated as we had to adjust the falls to the original flat roof so all the water would run to the back of the roof. The roof insulation was laid at the front of the roof to a depth of around 350mm, pushing the water to the back of the roof .

I also show you in this video some of the characteristics of EPDM rubber. EPDM rubber is flexible and when laid over soft insulation the completed roof is soft to walk on. Customers sometimes comment on this as if it’s a problem, however it’s not! That’s how it’s designed to be. The complete system is lightweight and designed to go over the top of other roof coverings such as felt and asphalt.

Liquid rubber flat roofing SD650 by 3M

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liquid rubber SD650 ny 3m flat roofing 31liquid rubber SD650 ny 3m flat roofing 30liquid rubber SD650 ny 3m flat roofing 29liquid rubber SD650 ny 3m flat roofing 28liquid rubber SD650 ny 3m flat roofing 27liquid rubber SD650 ny 3m flat roofing 26
liquid rubber SD650 ny 3m flat roofing 25liquid rubber SD650 ny 3m flat roofing 24liquid rubber SD650 ny 3m flat roofing 23liquid rubber SD650 ny 3m flat roofing 22liquid rubber SD650 ny 3m flat roofing 21liquid rubber SD650 ny 3m flat roofing 20
liquid rubber SD650 ny 3m flat roofing 19liquid rubber SD650 ny 3m flat roofing 18liquid rubber SD650 ny 3m flat roofing 17liquid rubber SD650 ny 3m flat roofing 16liquid rubber SD650 ny 3m flat roofing 15liquid rubber SD650 ny 3m flat roofing 14

Via Flickr:
The words Liquid Rubber are what most people perceive liquid roofing products to be, realistically out of the 15 or so liquid roofing materials on the market there is only one Liquid Rubber liquid roofing material that I know is actually liquid EPDM rubber, all the rest are liquid emulsion liquid polymers, or some other kind of material.
We are using 3M Scotchkote Urethane Roof Coating. SD650 is a two component, elastomeric, solvent-based urethane for flat roofs and its good, very good! Exactly what you would expect from 3M. It comes with a 25 year guarantee from 3M, when installed by a trained contractor, and yes, we are trained contractors. So if you need any info on the system please don’t hesitate to contact me: Steven Dickinson 07802 300 099 at London Flat Roofing Ltd.

This is a link to some of the videos on Youtube we have, showing this flat roofing system.
Time lapse video of a new flat roof
Cleaning an old asphalt roof
First coat detail round skylight

Camden Kensington Hammersmith Highgate Holborn Belsize Park Bloomsbury Camden Town Chalk Farm Covent Garden (also partly in Westminster) Dartmouth Park Fitzrovia Fortune Green Frognal Gospel Oak Hampstead Haverstock Highgate (also partly in the London Borough of Islington and the London Borough of Haringey) Holborn Kentish Town Kings Cross Peckwater Estate Primrose Hill Regent’s Park Estate Saffron Hill St. Giles St Pancras Somers Town South Hampstead Swiss Cottage Tufnell Park West End of London West Hampstead St Johns Wood

EPDM rubber flat roof North London

This is an EPDM roof we fitted 8 years ago. As you can see, apart from some dust, the roof is perfect as you would expect, as 8 years is only around a quarter of its expected lifespan.

Via Flickr:
If you look across the EPDM rubber roof you can see that we have made adjustments to the falls and how the flat roof drains, over in the far corner the insulation supplied by Kingspan and laid by falls in a different direction from the main roof, thus channeling the water to the outlets. EPDM can withstand water standing on it, however it’s never a good thing to do if you can channel it off.

The EPDM we used on this roof comes with a 20 year insurance-backed guarantee, and is expected to last for up to 40 years. There are different EPDM rubbers on the market, and they all come with different guarantees. We are trained installers of three different EPDM rubbers – some come in small sheets and some in large sheets, depending on the flat roof that we have to lay. The roof cover depends on what EPDM rubber waterproofing membrane we use. Please contact us at London Flat Roofing or call 020 8421 3193 for more information.

New EPDM roof over an old asphalt roof

We want to place a new EPDM roof over this Hi,
I’ve looked at the photos of the flat roofs you sent me. Both flat roofs will have to have hand rails around them before any work can be carried out. Realistically a working platform would be the best option, around 500mm down from the ridge, as the ridge tiles will have to be removed so that the flat roofing material can be dressed up and over the top of the ridge.

Both flat roofs will need to be cleaned then overlaid with OSB board before the new flat roofing EPDM Rubber can be installed. An alternative material that could be used is the 3M Scotchkote Urethane Roof Coating SD650. This is a two component, elastomeric, solvent-based urethane for flat roofs and is very light in colour so it reflects the heat of the day in the summer. If you are not going to insulate the roof then this is the best option. It goes directly over the old asphalt, with no need to lay the OSB, so the saving there covers the cost of the slightly more expensive system.