Chandler's Ford's interwar detached and semi-detached housing was built at a time when rear extensions were uncommon — but the post-war and 1960s–80s extension boom added flat-roofed kitchen, dining and utility extensions to a large proportion of the area's housing stock. Those extension flat roofs, built to the standards and materials of their time, are now 40–60 years old. Traditional felt systems on Chandler's Ford extensions have typically been replaced once already, and the replacement felt is itself now reaching end of life.
GRP Fibreglass for Chandler's Ford Extensions
GRP fibreglass is the system we recommend for most Chandler's Ford domestic flat roofs. The seamless liquid application eliminates the joint failures that cause traditional felt to leak, and the 25-year manufacturer warranty gives genuine long-term confidence. Chandler's Ford's position on the chalk ridge above the Itchen Valley means extensions on the western and north-western aspects of properties face significant rainfall — GRP's standing water performance is significantly better than felt in these conditions.
Deck Condition on Chandler's Ford Properties
Before any flat roof installation, we inspect the structural deck boards. On Chandler's Ford properties where the extension was built in the 1960s–70s, the original deck is often softwood chipboard or tongued-and-grooved boarding that has absorbed moisture over decades. Where deck boards are soft, delaminating or deflecting underfoot, we replace them as part of the installation. Deck replacement is included in the written quote after survey — we never install a new membrane over a compromised deck.
Free survey and written quote. No call-out fee. No obligation. Call 01962 809171.
Flat Roof Costs in Winchester (2025)
| Flat Roof Type | Typical Cost |
|---|---|
| GRP fibreglass — extension (20m²) | £1,800–£2,800 |
| GRP fibreglass — garage | £900–£1,600 |
| EPDM rubber — large extension | £1,600–£3,200 |
| Deck replacement (if required) | £150–£450 add |
| GRP manufacturer warranty | 25 years |
What a Flat Roof Survey Involves
We survey the existing membrane from the roof surface — checking for blistering, cracking, joint failure and drainage falls. We inspect the deck boards at the edges and any accessible areas for softness or delamination. We check the outlet drainage and confirm the fall direction. The written survey report confirms whether repair is appropriate or whether replacement is the better value decision, with costings for both options where repair is viable. Deck replacement cost, where required, is confirmed before work starts — not discovered and charged afterwards. Free survey and written fixed quote. Call 01962 809171.