- Guide price
- £2,650–£4,650
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Lancashire at a glance
- Largest towns
- Preston, Burnley, Blackburn, Blackpool
- Postcode areas
- BB, FY, L, LA, OL, PR, WN
- Building control
- Preston City Council, Burnley Borough Council, Blackburn with Darwen Borough Council and 10 other councils
- Neighbouring areas
- Greater Manchester · Merseyside · Cheshire · West Yorkshire
- Guide price region
- North West (−5% on West Midlands rates)
How much does a warm roof upgrade cost in Lancashire?
Guide prices 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 |
Which flat roofs are common in Lancashire?
Flat roofs in Lancashire sit on bungalows with flat-roofed side extensions and dormers, newer estates where the first extension roofs are now being replaced and lock-up garage blocks on estates. 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. Approximate 1991–2020 regional averages based on Met Office data.
Building regulations in England
Replacing more than half of a roof over a heated room usually counts as renovating a thermal element, so it is insulated to current standards and notified to building control. Renovated roofs over heated rooms are insulated to around 0.16 W/m²K where that's feasible, and new extension roofs are built to 0.15 W/m²K. In Lancashire the application goes to Preston City Council, Burnley Borough Council, Blackburn with Darwen Borough Council and 10 other councils. More on the rules.
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.
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.
Which towns in Lancashire do we cover?
- Preston
- Burnley
- Blackburn
- Blackpool
- Morecambe
- Lancaster
- Lytham St Annes
- Skelmersdale
- Leyland
- Accrington
- Chorley
- Darwen
- Thornton-Cleveleys
- Nelson
- Fleetwood
- Ormskirk
- Rawtenstall
- Colne
- Poulton-le-Fylde
- Heysham
- Haslingden
Warm roof insulation upgrades in Lancashire: questions
Which towns in Lancashire do you cover?
All of Lancashire. The main towns have their own pages below, and if yours isn't listed we still cover it: send your postcode and we'll confirm.
How much does a warm roof upgrade cost in Lancashire?
£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.
Which postcode areas do you cover in Lancashire?
All of Lancashire, including the BB, FY, L, LA, OL, PR, WN postcode areas. Send your full postcode and we'll confirm.
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 add insulation over my existing roof without stripping it?
Sometimes, if the existing covering and deck are dry and sound. We will check at the survey and explain the risks, and our overlay or strip guide covers this choice.
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.
Everything about warm roof insulation upgrades → · All flat roofing in Lancashire →