Chorley at a glance
- Postcode districts
- PR6, PR7
- Population
- about 33,888 (GeoNames)
- Council area
- Chorley Council
- Building approval
- Chorley Council building control, or a registered building control approver
- Nearest main town
- Wigan, about 7 miles
- Guide price region
- North West (−5% on West Midlands rates)
Why upgrade to a warm roof in Chorley?
Converting a garage, loft space or outbuilding to a room in Chorley changes what the roof needs to do. Once the space is heated, the roof is expected to perform to a higher standard, and a warm build-up is usually the simplest way to get there.
In a town like Chorley, flat roofs are commonly found on terraced streets with flat-roofed rear kitchens and bathrooms or newer estates where the first extension roofs are now being replaced. The North West is one of England's wetter regions, averaging roughly 1,290 mm of rain a year, so falls, outlets and well-detailed upstands matter more than the membrane colour.
How much does a warm roof upgrade cost in Chorley?
Guide price in Chorley: £2,650–£4,650 for a 20 m² extension roof in EPDM with a new deck and insulation, including VAT at North West 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 | £2,650–£4,650 |
| Extension (20 m²), EPDM with sedum green roof | £4,200–£7,700 |
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?
- New waterproofing, with a written workmanship guarantee
- Building control or building standards handled where needed
- Upstands, trims and kerbs reset to the new roof level
- 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?
Warm roof insulation upgrades in Chorley: questions
Do you cover Chorley?
Yes. Chorley is part of our Lancashire coverage, including postcode districts PR6, PR7. 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 Chorley?
Where the work needs approval it goes to Chorley 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 Chorley?
£2,650–£4,650 for a 20 m² extension roof in EPDM with a new deck and insulation, at North West guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
How thick does flat roof insulation need to be?
It depends on the insulation product and the U-value target. With common PIR boards, meeting a renovation target usually means well over 100 mm. Thinner, higher-performance boards are available where height is tight.
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.