- Price per m²
- £62–£108
- Typical life
- 15–25 years
- Manufacturer guarantees
- 10–20 year material guarantees on specified systems
- Typical garage roof
- £1,550–£2,700
Cornwall at a glance
How much does a torch-on felt roof cost in Cornwall?
Guide prices including VAT at South West rates. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Single garage (18 m²), torch-on felt | £1,550–£2,700 |
| Extension (20 m²), felt, new deck + insulation | £2,800–£4,850 |
| Block of flats (150 m²), felt + insulation + scaffold | £16,000–£28,000 |
| Single garage (18 m²), EPDM rubber | £1,650–£2,900 |
| Extension (20 m²), EPDM, new deck + insulation | £2,900–£5,050 |
Which flat roofs are common in Cornwall?
Flat roofs in Cornwall sit on 1930s semis with flat-roofed garages and kitchen extensions, shops with flat-roofed rear stores below flats and terraced streets with flat-roofed rear kitchens and bathrooms. The South West averages roughly 1,260 mm of rain a year and many roofs face wind off the Atlantic, so we specify fixings and edge details for wind uplift as well as drainage. 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 Cornwall the application goes to Cornwall Council. More on the rules.
Is torch-on roofing safe, and what is the difference between two- and three-layer systems?
Yes, torch-on is safe when hot works are properly controlled, because most roof fires linked to torching start at hidden timber or debris near edges and upstands, not on the open roof. Our teams follow a hot-works routine on every job:
- check eaves, fascias, soffits and wall cavities for timber, nests and debris before lighting a torch;
- use a cold-applied or self-adhesive membrane, rather than a flame, at edges, against combustible materials and in tight details;
- keep fire extinguishers on the roof and the gas bottles secured and away from the work;
- stop torching well before the team leaves, then carry out a fire watch so smouldering is spotted while people are still on site.
As for layers, a two-layer system (underlay plus cap sheet) is common on domestic roofs such as garages and extensions. A three-layer system adds an intermediate sheet, giving more thickness and redundancy, and is often specified on larger, commercial and multi-occupied roofs. The right choice depends on the size and use of the roof and the system's requirements, so we set it out in the quote.
Near a boundary, the external fire performance of the tested build-up, such as a BROOF(t4) classification, can also matter, and we check it where it applies.
Should I choose torch-on felt or a different flat roof system?
Choose torch-on felt when you want a proven, layered system at a sensible price, particularly on larger roofs, blocks of flats and commercial buildings where several layers give useful redundancy. It is a weaker choice where hot works are hard to manage safely.
For: generally lower cost per square metre; two or three layers, so a single defect in one layer need not cause a leak; tough mineral finish; long track record and a British Standard code of practice; repairs can be made with compatible materials.
Against: needs a naked flame unless a cold-applied or self-adhesive alternative is used; shorter typical life than EPDM or GRP; the finish is functional rather than decorative; more laps to detail than a single sheet.
On small domestic roofs near timber, EPDM avoids the torch entirely. GRP gives a harder, neater surface. For an overlay, a liquid-applied system is often simpler. Large commercial roofs may suit single-ply, and older buildings may suit mastic asphalt. See our comparison guide.
Which towns in Cornwall do we cover?
Torch-on felt roofing in Cornwall: questions
Which towns in Cornwall do you cover?
All of Cornwall. 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 torch-on felt roof cost in Cornwall?
£1,550–£2,700 for a typical 18 m² garage roof in torch-on felt, at South West guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Which council handles building control for a flat roof in Cornwall?
It depends on where the roof is: in Cornwall that's Cornwall Council. 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. We confirm which applies at the survey.
How long does it take to lay a torch-on felt roof?
A garage roof typically takes one to two days and an insulated extension two to three. Larger roofs and blocks are phased over longer, with each area made weathertight before the team leaves.
Can torch-on felt go over an existing felt roof?
Sometimes, if the old roof is dry, well bonded and the deck is sound. Often stripping is better, because overlaying can trap moisture and hide rot; our guide to overlay or strip explains how we decide.
Is torch-on felt better than the old felt roofs?
Yes, considerably. Modern torch-on membranes are polymer-modified and polyester-reinforced, laid in bonded layers, and typically last much longer than the older felt systems they replace.
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