High Wycombe at a glance
- Postcode districts
- HP11, HP12, HP13
- Population
- about 133,204 (GeoNames)
- Council area
- Buckinghamshire Council
- Building approval
- Buckinghamshire Council building control, or a registered building control approver
- Nearest main town
- Slough, about 11 miles
- Guide price region
- South East (+10% on West Midlands rates)
What makes a good extension roof in High Wycombe?
Selling a house in High Wycombe with a tired extension roof can raise questions in the buyer's survey. A recent replacement, with building control sign-off where needed and written guarantees, gives a buyer confidence and removes a likely point of negotiation.
In and around High Wycombe, flat roofs are typically found on low-rise post-war blocks of flats, and on lock-up garage blocks on estates. 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 new extension roof cost in High Wycombe?
For High Wycombe we use South East rates: £3,100–£5,350 is the guide for a 20 m² extension roof in EPDM with a new deck and insulation, VAT included. 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), GRP, new deck + insulation | £3,300–£5,900 |
| Extension (20 m²), EPDM, insulation + 1 rooflight upstand | £3,300–£5,750 |
| Single garage (18 m²), EPDM rubber | £1,750–£3,100 |
Why does water pond or leak where the extension meets the house?
Usually because the fall runs the wrong way, the abutment detail has failed, or the roof has sagged close to the wall. The junction with the house is the most common leak point on an extension roof.
If the roof falls towards the house, or the deck dips near the wall, water sits against the upstand and finds any weakness in the flashing above. Older roofs often have the felt simply turned up the brickwork with no cover flashing, or a flashing that has pulled out of its joint. A patch will not change a fall. We re-firr or use tapered insulation so water runs away from the wall, then form a new upstand, usually 150 mm above the finished roof, with a flashing chased into the mortar joint.
Rooflights and lanterns are the other weak point. A lantern needs a properly built kerb with the membrane dressed up and under its frame. We rebuild rooflight upstands within the roof job; we do not supply the lantern itself. Our guide to ponding water explains the causes in more depth.
What's included?
- Free survey of the roof, abutment and room below
- New deck, vapour control layer and warm-roof insulation
- Building control handled where needed, and a written workmanship guarantee
- New abutment upstand and flashing, plus rebuilt rooflight kerbs
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?
- Marlow · 4 mi
- Amersham · 6 mi
- Maidenhead · 7 mi
- Chesham · 8 mi
- Chalfont Saint Peter · 8 mi
- Gerrards Cross · 9 mi
Extension and kitchen roofs in High Wycombe: questions
Do you cover High Wycombe?
Yes. High Wycombe is part of our Buckinghamshire coverage, including postcode districts HP11, HP12, HP13. 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 High Wycombe?
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 new extension roof cost in High Wycombe?
£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.
Can a sedum roof go on my extension?
Possibly, if the structure can carry the extra weight and the roof has suitable falls and drainage. We check the joists at survey before recommending it.
Will a new extension roof sit higher than the old one?
Usually, by the thickness of the added insulation. We check the height against the upstairs window sills, door thresholds and wall flashings at survey so everything still works.