Chichester at a glance
- Postcode districts
- PO19
- Population
- about 31,654 (GeoNames)
- Council area
- Chichester District Council
- Building approval
- Chichester District Council building control, or a registered building control approver
- Nearest main town
- Portsmouth, about 14 miles
- Guide price region
- South East (+10% on West Midlands rates)
Why upgrade to a warm roof in Chichester?
Many flat-roofed extensions and dormers in Chichester 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.
Chichester's flat roofs are mostly on low-rise post-war blocks of flats, with plenty on 1960s and 1970s link-detached houses with flat-roofed garages and porches too. 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 Chichester?
Guide price in Chichester: £3,100–£5,350 for a 20 m² extension roof in EPDM with a new deck and insulation, including VAT at South East 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 | £3,100–£5,350 |
| Extension (20 m²), EPDM with sedum green roof | £4,850–£8,900 |
Can a cold flat roof be converted to a warm roof?
Yes, and it is the usual approach when an older cold roof is re-covered. The old covering is stripped, the deck is checked and replaced where needed, and the vapour control layer, insulation and new waterproofing go on top.
The existing insulation between the joists is assessed at the same time. Leaving it in place can create a cold, unventilated gap that traps moisture, so it is often removed or the build-up is designed so that most of the insulation sits above the deck. We decide this case by case once we can see inside the roof. If the covering is still sound and you are only patching it, the upgrade isn't usually required, and our repair or replace guide explains how to decide between the two.
What's included?
- Vapour control layer on the warm side of the insulation
- Rigid insulation boards sized to the U-value target
- New waterproofing, with a written workmanship guarantee
- Building control or building standards handled where needed
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?
- Bognor Regis · 6 mi
- Emsworth · 7 mi
- Hayling Island · 9 mi
- Havant · 9 mi
- Littlehampton · 11 mi
- Waterlooville · 11 mi
Warm roof insulation upgrades in Chichester: questions
Do you cover Chichester?
Yes. Chichester is part of our West Sussex coverage, including postcode districts PO19. 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 Chichester?
Where the work needs approval it goes to Chichester District 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 Chichester?
£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 there VAT relief on flat roof insulation?
Don't count on it. Insulation fitted as part of a roof replacement is usually treated as part of a single standard-rated job. Check your own case with HMRC guidance or an adviser.
Can you insulate a flat roof from inside instead?
It is possible, but insulating between or under the joists creates a cold roof, which needs ventilation and carries a higher condensation risk. When the roof is being re-covered anyway, a warm roof from above is usually the better option.