GRP fibreglass, EPDM rubber and felt flat roofing systems for extensions, garages and outbuildings across Tonbridge. We recommend GRP for the Medway Valley climate — seamless, long-lasting and fully waterproof from day one.
Three systems, each suited to different applications. We'll recommend the right one after a free survey.
Our most-installed system in Tonbridge. Fully seamless — no joints, no laps, no weak points. The laminated fibreglass shell is impervious to the elevated humidity found in lower Tonbridge near the Medway. 20–25 year system warranty. Ideal for extensions, flat-topped dormers and most garage roofs.
EPDM is a single-ply rubber membrane suited to larger or more complex flat roof shapes where GRP lamination is less practical. Excellent flexibility means it accommodates thermal movement without cracking. 20-year warranty and fully compatible with green roof build-ups if desired.
Three-layer high-performance felt is still appropriate for budget-sensitive jobs on straightforward surfaces. We use torch-on polyester-reinforced felt as a minimum — no single-layer felt installs. Typical lifespan 15–20 years in the Tonbridge climate with annual maintenance.
Flat roofs need correct falls to drain. Ponding water is the main accelerant of membrane failure. We survey existing drainage and install or improve outlets, drip edges and internal drainage channels as part of every flat roof installation.
If the existing deck (plywood or OSB) has suffered moisture ingress, we replace it before installing the new membrane. A new waterproof system over a rotten deck will fail — we always check and report honestly.
Older flat roofs are often "cold roof" construction — inadequately insulated and prone to condensation issues. We offer warm roof upgrades combining new insulation board with GRP or EPDM to eliminate interstitial condensation and improve thermal performance.
| System & Area | Typical Cost | Warranty |
|---|---|---|
| GRP fibreglass — small extension (up to 15m²) | £900–£1,800 | 20–25 years |
| GRP fibreglass — medium extension (15–30m²) | £1,800–£3,500 | 20–25 years |
| EPDM rubber — large garage or flat (30m²+) | £2,500–£5,000 | 20 years |
| Felt overlay (3-layer torch-on) | £600–£2,000 | 15–20 years |
| Deck replacement (inc. membrane) | Add £200–£600 | — |
Call 0173 224 1138 for a no-obligation survey and written quote. We'll inspect the existing deck, assess drainage and recommend the right system for your budget and property.
"Rear extension flat roof had been leaking for two winters. Previous roofer had patched the felt twice. These guys stripped it back, found the deck was sound and installed GRP. Two years on, no issues whatsoever."
"New GRP system on a large garage. Clean job, quick — done in a day and a half. The finish is excellent and the quote they gave was exactly what we paid."
"Flat roof on the garden room had ponding water and the felt was blistering. They recommended EPDM for the slight pitch and installed it in a day. Much better than felt and comes with a proper warranty."
A typical rear extension flat roof in Tonbridge (12–20m²) costs £900–£2,200 in GRP fibreglass. Larger garage or outbuilding roofs run £2,000–£5,000. GRP is our recommended system for the Medway Valley climate — free quotes available on 0173 224 1138.
The elevated humidity in lower Tonbridge — particularly near the Medway — shortens the lifespan of traditional felt to 10–15 years. GRP fibreglass forms a seamless, fully waterproof shell with a 20–25 year warranty and no joints to fail. It's the system we recommend for almost all Tonbridge flat roof replacements.
Often yes. If the deck is sound and the felt or membrane is localised in failure, we can repair or overlay rather than strip back. We'll tell you honestly after inspection whether repair or replacement is the better value option.
Like-for-like replacement or repair of a flat roof does not require planning permission. If you're raising the height or changing the structure, permitted development rules apply. We'll flag any planning considerations during the survey.
GRP fibreglass for most extensions up to ~40m². It's seamless and handles Kent conditions well. EPDM for larger or more complex shapes. We specify after a free survey.
Isolated splits, blisters or failed outlets can often be repaired. Once the deck has absorbed moisture, or membrane failure is widespread, replacement is better value. Free survey confirms which applies on your Tonbridge property.
GRP on a typical kitchen extension: 1–2 days including deck preparation. Larger garage or complex area: 2–3 days. We leave the surface cured and ready before scaffolding comes down.
Medway Valley frost pocket position — more freeze-thaw cycles than elevated surrounding towns. For flat roofing work in Tonbridge, this means the dominant failure pattern and the correct specification both reflect local conditions rather than generic UK roofing standards.
The housing stock across Tonbridge — Victorian and Edwardian clay plain tile, 1960s-80s concrete interlocking, post-war semis throughout — creates a specific set of requirements that we address differently here than elsewhere in our coverage area. Properties on Pembury Road and Vale Road demonstrate this most clearly: the roofing issues we see there reflect the intersection of era, construction method and local exposure in ways that a non-local contractor would not anticipate from the specification alone.
Haysden Country Park and Medway riverside generate above-average moss and leaf fall debris. We factor this into every survey and quote on Tonbridge properties — it is the difference between a repair that lasts five years and one that lasts thirty.
Tonbridge is our base from our Tonbridge base. Survey appointments within 2–3 working days. Emergency cover 24/7. Free written quote on 0173 224 1138.
Every flat roofing job in Tonbridge follows the same process: free on-roof survey, written quote specifying materials and scope, scheduled start date, clean completion and written guarantee. No provisional sums, no verbal agreements, no hidden costs added on the day.
We inspect on-roof — not from the ground, not from a photograph. A survey for flat roofing work in Tonbridge takes 45–90 minutes depending on complexity. We assess not just the immediate fault but the condition of adjacent elements that might affect the repair scope or lifespan.
Written quote within 24 hours of survey. Every quote states: the specific materials by grade and code, the full scope of work, access method (scaffold or ladder), and the guarantee terms. If we find something additional during the job, we stop and agree the cost before proceeding.
On completion we photograph the finished work, clear all debris and issue the written guarantee. For work involving new lead, we photograph the joint method and lead code before any tile courses are replaced. For flat roof work, we photograph the finished membrane surface before trimming. These records protect you and provide evidence for any future insurance or sale requirements.
Free inspection, honest system recommendation, written fixed-price quote. No obligation.
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