Hemel Hempstead at a glance
- Postcode districts
- HP1, HP2, HP3
- Population
- about 95,961 (GeoNames)
- Council area
- Dacorum Borough Council
- Building approval
- Dacorum Borough Council building control, or a registered building control approver
- Nearest main town
- Watford, about 7 miles
- Guide price region
- East of England (+5% on West Midlands rates)
What makes a good extension roof in Hemel Hempstead?
Extension roofs in Hemel Hempstead are often replaced because the original was built cheaply: thin chipboard decks, little or no insulation and felt turned up the wall without a proper flashing. Twenty or thirty years on, those weaknesses show up as leaks at the back wall and a cold, damp ceiling.
Hemel Hempstead's flat roofs are mostly on 1930s semis with flat-roofed garages and kitchen extensions, with plenty on terraced streets with flat-roofed rear kitchens and bathrooms too. The East of England is the driest part of Britain, with parts of the Anglian region around 630 mm a year, so summer heat and UV, not rainfall, do most of the ageing on a felt roof.
How much does a new extension roof cost in Hemel Hempstead?
Guide price in Hemel Hempstead: £2,950–£5,150 for a 20 m² extension roof in EPDM with a new deck and insulation, including VAT at East of England rates. 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 | £2,950–£5,150 |
| Extension (20 m²), GRP, new deck + insulation | £3,150–£5,650 |
| Extension (20 m²), EPDM, insulation + 1 rooflight upstand | £3,150–£5,500 |
| Single garage (18 m²), EPDM rubber | £1,700–£2,950 |
How long will my kitchen be disrupted by a new roof?
Most single-storey extension roofs are replaced in two to four working days, depending on size, rooflights and weather. The kitchen usually stays in use throughout.
Expect noise during the strip-out, and occasional dust through gaps around old rooflights, so it helps to cover worktops and move anything fragile off high shelves. We strip only what we can make weathertight by the end of each day. If a rooflight or lantern is being lifted and refitted, there may be a temporary cover over the opening for a short time. Resin systems smell while they cure, so keep the windows below the roof closed on that day.
What's included?
- Falls set away from the house wall
- Free survey of the roof, abutment and room below
- Staged strip-out so the room stays weathertight
- New deck, vapour control layer and warm-roof 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?
Extension and kitchen roofs in Hemel Hempstead: questions
Do you cover Hemel Hempstead?
Yes. Hemel Hempstead is part of our Hertfordshire coverage, including postcode districts HP1, HP2, HP3. 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 Hemel Hempstead?
Where the work needs approval it goes to Dacorum Borough 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 Hemel Hempstead?
£2,950–£5,150 for a 20 m² extension roof in EPDM with a new deck and insulation, at East of England guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
How do I know my extension roof needs replacing rather than repairing?
Repeated leaks, a soft deck, wet insulation or widespread cracking point to replacement. A single defect on a dry, sound roof can usually be repaired.
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.