The Technical Reality of Roofing a Garage
When it comes to roofing a garage in Sussex, property owners usually face the exact same structural failure: traditional blown-bitumen felt that has hardened, blistered under UV exposure, and cracked due to thermal movement. As an independent roofer with 18 years of experience, a massive part of my daily work here in Brighton and Hove involves stripping these failed coverings and addressing the structural moisture ingress underneath.
Why Garage Roofs Fail: Standalone vs. Terraced Blocks
Garage roofs are almost exclusively designed as ‘cold roof‘ systems, meaning there is no thermal insulation between the timber joists. This exposes the roof deck to rapid, extreme temperature fluctuations. In the summer, the roof deck expands; in the winter, it contracts. Standard, outdated roofing felt simply cannot handle this constant thermal movement. It eventually splits, allowing capillary action to draw rainwater straight into the decking and causing timber rot.
I frequently work on both standalone single garages and continuous rows of terraced garages. Interestingly, the underlying building physics and repair methods are highly standardized. The primary difference when dealing with a row of garages lies in the party wall junctions. If a neighboring roof is failing, water can travel laterally under the dividing trims. To prevent this, I install highly secure, watertight termination bars and independent upstands to permanently isolate your roof unit from adjacent leaks.
The SBS Torch-On Solution
I do not patch rotten, aged felt. The only permanent solution is to strip the old membrane down to the joists, inspect for structural integrity, and install a fresh deck using 18mm OSB3 tongue-and-groove boards. Over this structural base, I install a high-performance SBS-modified (Styrene Butadiene Styrene) bitumen system. The SBS technology incorporates synthetic rubber into the bitumen, providing the flexibility required to expand and contract with the coastal Sussex weather without snapping.
If you are looking at replacing your garage flat roof, it is critical to use an SBS system complete with rigid drip edges to direct surface water efficiently into the guttering and away from the masonry.
Standardized Pricing and Instant Estimates
Because garage structures—whether standalone or part of a terraced block—are highly standardized, pricing the replacement is incredibly straightforward. You don’t need to deal with the typical roofing industry delays or hidden fees. I have engineered my online calculator to be the absolute most precise tool available for calculating garage roof replacements. Now that you understand the technical requirements of a cold roof system, you can use my website’s calculator to generate an exact, no-commitment price estimate for the required materials and labor in just 30 seconds.