EPDM vs GRP Flat Roof: Cost, Lifespan and Which to Choose

EPDM vs GRP compared

Here are the two coverings on Checkatrade’s flat roof figures, with its repair prices per m². Every price excludes VAT.

	EPDM rubber	GRP fibreglass
Price per m²	£80 to £100	£95 to £120
Average per m²	£90	£107.50
Lifespan	30 to 50 years if professionally installed and maintained	Up to 30 years
Repair per m², up to 3 m²	£120 to £170	£130 to £180
Colours	Black only	Can be finished in colours
Installation	Large sheets that minimise seams, bonded with adhesive or mechanical fixing	Needs dry weather, and layering and curing take longer
Weak point	Can be punctured by sharp objects	Can crack in very cold conditions

EPDM is cheaper to fit and to repair, and it lasts longer. GRP’s advantage is colour, so it suits a roof where black will not do and the work can wait for dry weather.

EPDM vs GRP cost per m²

A flat roof replacement costs £80 to £100 per m² in EPDM rubber and £95 to £120 per m² in GRP fibreglass on Checkatrade’s prices, so GRP costs £15 more per m² at the bottom of the range and £20 more at the top.

At Checkatrade’s averages of £90 and £107.50 per m², each m² of GRP adds £17.50, so the gap on your own roof is its area in m² multiplied by £17.50.

EPDM vs GRP lifespan

EPDM lasts 30 to 50 years if professionally installed and maintained, and GRP up to 30 years, on Checkatrade’s lifespans, so EPDM’s shortest lifespan matches GRP’s longest. For comparison, a torch-on felt roof lasts 15 to 20 years and asphalt 20 to 30 on the same Checkatrade figures.

EPDM stays cheaper per year of use. On Checkatrade’s averages, EPDM at £90 per m² costs £1.80 to £3.00 per m² a year over 30 to 50 years, while GRP at £107.50 costs at least £3.58 per m² a year, since 30 years is the most it lasts.

Colour and installation

EPDM comes in black only, in large sheets that minimise seams, bonded with adhesive or mechanical fixing, on Checkatrade’s flat roof guide. GRP can be finished in colours, but it needs dry weather to install, and the layering and curing make the job take longer.

If black will not suit the roof, GRP gives you a colour, as long as you can book it for a dry spell and allow for the longer job. Whichever you pick, get the way it goes on written into the quote.

EPDM and GRP repair costs

Repairs up to 3 m² cost £120 to £170 per m² on EPDM rubber and £130 to £180 per m² on GRP fibreglass, on Checkatrade’s repair prices. A 3 m² repair, the largest those rates cover, comes to £360 to £510 in EPDM and £390 to £540 in GRP on the same repair figures.

Each covering has its own weak point: sharp objects can puncture EPDM, and GRP can crack in very cold conditions.

EPDM or GRP for a garage roof

On Checkatrade’s garage roof prices, rubber costs £70 to £100 per m² and fibreglass £90 to £130, excluding VAT, so fibreglass costs £20 more per m² at the bottom of the range and £30 more at the top. On a 15 m² garage roof, that is £1,050 to £1,500 in rubber against £1,350 to £1,950 in fibreglass on the same garage figures.

The choice follows the same lines as any flat roof: rubber for the lower price, and fibreglass if the garage roof needs a colour other than black.

EPDM or GRP: which to choose

Pick the covering by what your roof needs most.

• The lowest price: EPDM, which costs less per m² than GRP to fit and to repair.
• The longest lifespan: EPDM, as long as it is professionally installed and maintained.
• A colour other than black: GRP, since EPDM comes in black only.

Whichever you lean towards, get both coverings priced for the same roof, so the difference between the quotes is the real one.

Weigh the guarantee alongside the price, because guarantee lengths differ between Nottingham roofers: Rain Defence Roofing in Beeston, a licensed Firestone EPDM contractor, guarantees its roofs for 20 years, B&S Roofing in Eastwood gives flat roofing a 20-year guarantee, and Roofcare (Midlands) in West Bridgford guarantees Firestone rubber roofs for 10 years.