Which flat roof system is best for my extension?

For extensions, we typically recommend GRP fibreglass due to its seamless finish, 25+ year lifespan, and ability to be walked on. EPDM is a great alternative for larger areas or tighter budgets. Our roofers will assess your specific needs during a free survey.

How long do flat roofs last?

Modern flat roofing systems last much longer than traditional felt. GRP fibreglass lasts 25-30+ years, EPDM rubber 30+ years, and modern built-up felt 15-20 years. Proper installation by accredited professionals is key to achieving these lifespans.

Can I walk on my flat roof?

GRP fibreglass roofs are designed to be walked on and are ideal for balconies and roof terraces. EPDM can handle light foot traffic. Traditional felt should only be walked on for maintenance. Your roofer will advise on the best system for your intended use.

How much does a flat roof cost?

Flat roof costs depend on size, system, and access. As a guide: felt costs £40-60/m², EPDM £60-80/m², and GRP £80-120/m². For a typical garage (15m²), expect £600-900 for felt, £900-1,200 for EPDM, or £1,200-1,800 for GRP including labour.

What causes flat roofs to leak?

Common causes include poor installation, age-related deterioration, ponding water, failed flashings, and debris accumulation. Modern systems like GRP and EPDM largely eliminate these issues when properly installed by accredited professionals.

Can you install a flat roof in winter?

GRP fibreglass requires temperatures above 5°C and dry conditions, so winter installation can be challenging. EPDM is more flexible and can be installed in cooler weather. Your roofer will advise on the best timing and may use temporary weatherproofing if needed.

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Modern Flat Roofing Solutions

Flat roofs require specialist knowledge and the right materials. We connect you with accredited flat roofing experts who can advise on the perfect solution for your property and budget.

House extensionsGarage roofsDormer windowsGarden officesBalconies & terracesBay window roofsOutbuildingsCommercial properties

Find Specialists for Every System

Each system has its strengths. Our accredited roofers will help you pick the right one based on your property, budget, and how the roof will be used.

GRP Fibreglass

The Premium Choice

Glass Reinforced Plastic (GRP) is the gold standard in flat roofing. It creates a seamless, watertight finish that's virtually maintenance-free and comes in a range of colours.

Key Benefits:

25+ year lifespan
Seamless, watertight finish
UV stable - no cracking or fading
Can be walked on safely
Fire resistant
Ideal for balconies and walkways

Ideal for: Extensions, dormers, balconies, and anywhere requiring a long-lasting, premium finish.

EPDM Rubber

The Reliable Choice

Ethylene Propylene Diene Monomer (EPDM) is a highly durable synthetic rubber membrane. It's flexible, UV resistant, and excellent for covering large areas cost-effectively.

Key Benefits:

30+ year lifespan
Highly flexible - expands and contracts
UV and weather resistant
Low maintenance
Environmentally friendly
Quick installation

Ideal for: Garages, garden buildings, larger flat roofs, and green roof systems.

Built-Up Felt

The Traditional Choice

Modern high-performance felt systems have come a long way from the old-style felt. Multiple layers create a robust, waterproof barrier that's proven over decades of use.

Key Benefits:

15-20 year lifespan
Cost-effective solution
Proven technology
Good for repairs/overlays
Quick installation
Suitable for most budgets

Ideal for: Budget-conscious projects, shed roofs, and properties where cost is a primary concern.

At a Glance Comparison

Feature	GRP Fibreglass	EPDM Rubber	Built-Up Felt
Lifespan	25+ years	30+ years	15-20 years
Cost	£££	££	£
Maintenance	Very Low	Low	Moderate
Walkable		Limited	No
Seamless Finish		Joints	Overlaps