- Price per m²
- £55–£97
- Typical life
- 15–25 years
- Manufacturer guarantees
- 10–20 year material guarantees on specified systems
- Typical garage roof
- £1,400–£2,400
Monmouthshire at a glance
- Largest towns
- Abergavenny, Chepstow, Monmouth, Caldicot
- Postcode areas
- NP
- Building control
- Monmouthshire County Council
- Neighbouring areas
- Torfaen · Newport · Caerphilly · Blaenau Gwent
- Guide price region
- Wales (−8% on West Midlands rates)
How much does a torch-on felt roof cost in Monmouthshire?
Guide prices including VAT at Wales 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 | £1,400–£2,400 |
| Extension (20 m²), felt, new deck + insulation | £2,500–£4,300 |
| Block of flats (150 m²), felt + insulation + scaffold | £14,300–£25,000 |
| Single garage (18 m²), EPDM rubber | £1,450–£2,600 |
| Extension (20 m²), EPDM, new deck + insulation | £2,600–£4,500 |
Which flat roofs are common in Monmouthshire?
Flat roofs in Monmouthshire sit on lock-up garage blocks on estates, 1960s and 1970s link-detached houses with flat-roofed garages and porches and low-rise post-war blocks of flats. Wales averages roughly 1,460 mm of rain a year, among the wettest in Britain, so we design for steady run-off: proper falls, clear outlets and upstands well above the finished roof. Approximate 1991–2020 regional averages based on Met Office data.
Building regulations in Wales
Welsh guidance is that most re-roofing needs building control approval, so it's worth checking whenever more than a quarter of a roof is replaced or repaired. Renovated roofs are upgraded to around 0.16 W/m²K where feasible, and new extension roofs are built to 0.13 W/m²K under the Welsh Approved Document L. In Monmouthshire the application goes to Monmouthshire County Council. More on the rules.
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.
How long does a torch-on felt roof last, and what is the guarantee?
A modern torch-on roof typically lasts 15 to 25 years, and high-performance systems with better membranes can last longer. That is a big step up from older felt roofs, which were often single-layer, unreinforced or poorly bonded.
What shortens the life of a felt roof is usually visible: mineral chippings worn away so the bitumen is exposed to sunlight, blisters where moisture was trapped, split laps, and upstands that have slumped or pulled away from the wall. Ponding speeds all of this up.
Manufacturer material guarantees are available on many specified torch-on systems; they often depend on a particular build-up and registration, which we handle where the system allows. Every re-roof also comes with our written workmanship guarantee, the length of which is stated in the quote, and insurance-backed options can be discussed. Our flat roof lifespan guide compares felt with the other systems.
Which towns in Monmouthshire do we cover?
Torch-on felt roofing in Monmouthshire: questions
Which towns in Monmouthshire do you cover?
All of Monmouthshire. 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 Monmouthshire?
£1,400–£2,400 for a typical 18 m² garage roof in torch-on felt, at Wales 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 Monmouthshire?
It depends on where the roof is: in Monmouthshire that's Monmouthshire County Council. Welsh guidance is that most re-roofing needs building control approval, so it's worth checking whenever more than a quarter of a roof is replaced or repaired. We confirm which applies at the survey.
Can torch-on felt be laid in wet weather?
Not in rain or on a wet deck, because moisture trapped under the membrane causes blisters. Light cold weather is usually workable, but we will postpone rather than lay on a damp surface.
Is torch-on suitable for a block of flats?
Yes, layered bitumen systems are widely used on blocks of flats and commercial buildings. Larger roofs often use three layers and insulation, with hot works planned around residents.
Why does my felt roof have blisters?
Blisters usually form when moisture or air trapped beneath the felt expands in the sun. A few small, intact blisters may be monitored, but widespread or split blisters point to a repair or replacement.
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