GRP Fibreglass Roofing Cost Guide UK 2026

GRP (Glass Reinforced Plastic) fibreglass roofing is the go-to system for domestic extensions and garages across the UK. It's durable, seamless, and gives a clean professional finish. Here's what it costs in 2026.

Typical GRP Roofing Costs

• Small garage (15m²): £900–£1,600
• Single-storey extension (25–40m²): £1,600–£3,000
• Large flat roof (50–80m²): £3,000–£5,000
• Commercial installation (100m²+): Price on application

What Affects the Price?

The main cost factors are roof size, whether old material needs stripping, the amount of rotten decking to replace, insulation specification, complexity of shape (dormers, rooflights, penetrations), and access requirements.

Why GRP Costs More Than Felt

GRP fibreglass costs more per square metre than traditional felt. However, with a 25–30 year lifespan versus 10–15 years for felt, the lifetime cost is significantly lower. The superior performance and aesthetic finish also justify the premium.

Getting a Quote

A reputable GRP installer should visit to survey the roof before quoting — avoid anyone who quotes remotely based on description alone. Ensure the quote specifies the brand of GRP resin and topcoat used, as quality varies considerably.