Gerrards Cross at a glance
- Postcode districts
- SL9
- Population
- about 20,633 (GeoNames)
- Council area
- Buckinghamshire Council
- Building approval
- Buckinghamshire Council building control, or a registered building control approver
- Nearest main town
- Slough, about 6 miles
- Guide price region
- South East (+10% on West Midlands rates)
Why upgrade to a warm roof in Gerrards Cross?
Many flat-roofed extensions and dormers in Gerrards Cross were built with little or no insulation, or with a cold roof that was never properly ventilated. Those rooms are often hard to heat in winter and can suffer condensation, mould and, in time, a rotten deck.
In and around Gerrards Cross, flat roofs are typically found on terraced streets with flat-roofed rear kitchens and bathrooms, and on newer estates where the first extension roofs are now being replaced. Much of the South East sits in the drier Thames catchment at roughly 730 mm of rain a year, so the usual failures are at joints, upstands and outlets rather than from sheer volume of rain.
How much does a warm roof upgrade cost in Gerrards Cross?
At South East guide rates, a 20 m² extension roof in EPDM with a new deck and insulation comes to £3,100–£5,350 including VAT. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM, new deck + insulation | £3,100–£5,350 |
| Extension (20 m²), EPDM with sedum green roof | £4,850–£8,900 |
Do I have to insulate my flat roof when I replace it?
Usually, yes, if the roof is over a heated room and you are replacing more than half of its covering. In England, Wales and Northern Ireland, that counts as renovating a thermal element, so the roof should be upgraded to the renovation standard where that is technically, functionally and economically feasible.
The rules don't usually apply to patch repairs, or to an unheated, detached garage. The target U-value depends on where you live:
| Nation | Roof renovation target |
|---|---|
| England | 0.16 W/m²K (homes), 0.18 (non-domestic) |
| Wales | 0.16 W/m²K |
| Scotland | Section 6 framework, with a domestic benchmark of 0.12 W/m²K pursued as far as reasonably practicable |
| Northern Ireland | 0.18 W/m²K |
A new extension roof has a tighter target than a renovation: 0.15 in England and 0.13 in Wales. The economic test in England's guidance is a simple payback within 15 years. We handle building control or building standards where it is needed. The building regulations page sets out the approval routes in each nation.
What's included?
- Upstands, trims and kerbs reset to the new roof level
- Building control or building standards handled where needed
- Survey of the deck, joists and existing insulation
- Vapour control layer on the warm side of the insulation
Building regulations in England
Replacing more than half of a flat roof over a heated room usually counts as renovating a thermal element, so the roof is insulated to around 0.16 W/m²K where that's technically and economically feasible, and the work is notified to building control: the council or a registered building control approver, unless a registered competent person self-certifies it. A roof on a new extension is built to 0.15 W/m²K. Patch repairs, and most unheated detached garages, don't trigger the upgrade. Structural changes, or a new covering that adds 15% or more to the roof's weight, also need approval. More on the rules.
Which nearby areas do we also cover?
- Chalfont Saint Peter · 2 mi
- Rickmansworth · 5 mi
- Slough · 6 mi
- Amersham · 6 mi
- Windsor · 7 mi
- Chesham · 8 mi
Warm roof insulation upgrades in Gerrards Cross: questions
Do you cover Gerrards Cross?
Yes. Gerrards Cross is part of our Buckinghamshire coverage, including postcode districts SL9. Surveys and roofs are carried out by vetted roofing teams working under S&K Property Investments and Improvement Ltd.
Who checks building regulations for a flat roof in Gerrards Cross?
Where the work needs approval it goes to Buckinghamshire Council building control, or a registered building control approver. We tell you at the survey whether your job needs it and deal with the paperwork as part of the quote.
How much does a warm roof upgrade cost in Gerrards Cross?
£3,100–£5,350 for a 20 m² extension roof in EPDM with a new deck and insulation, at South East guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Is a warm roof worth it on a garage?
On a detached, unheated garage, usually not, as there is no heated space to protect and the thermal rules don't normally apply. On an integral or heated garage, or one being converted into a room, it is.
Will a warm roof make my room warmer?
Usually, yes. A room under a poorly insulated flat roof loses less heat once the roof is upgraded and tends to feel more even in temperature. How much difference you notice depends on how the roof was built before.