- Price per m²
- £88–£155
- Typical life
- 30–60 years
- Manufacturer guarantees
- 15-year material, up to 25-year system guarantees
- 30 m² roof
- £3,550–£6,450
Cornwall at a glance
How much does mastic asphalt roofing 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 |
|---|---|
| Mastic asphalt roof (30 m²), scaffold | £3,550–£6,450 |
| Localised patch repair | £150–£520 |
| 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 terraced streets with flat-roofed rear kitchens and bathrooms, shops with flat-roofed rear stores below flats and 1960s and 1970s link-detached houses with flat-roofed garages and porches. 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.
What building regulations apply when an asphalt roof is replaced?
Replacing more than half of an asphalt roof over a heated space usually counts as renovating a thermal element in England, Wales and Northern Ireland, so the roof should be insulated towards the renovation standard where technically and economically feasible; Scottish owners should check with the local authority's building standards service whether the work needs a warrant.
On older buildings, adding insulation can be constrained by parapet heights, door thresholds and the character of the building, and the regulations allow for what is technically feasible. In England, a new covering that adds 15% or more to the roof's weight also needs approval, so a switch to heavier asphalt is checked against the structure. Listed buildings may need listed building consent for changes to their character. We deal with building control or building standards where needed; see the building regulations page.
How long does mastic asphalt last, and what guarantees are available?
Mastic asphalt is one of the longest-lasting flat roof systems, typically giving 30 to 60 years with good specification and maintenance. Many older asphalt roofs are still watertight decades after they were laid.
Age does show eventually. Common signs include crazing and cracking from sun exposure, blisters where moisture has been trapped beneath, splits at skirtings where the building has moved, and ponding where the deck has settled. Regular maintenance, such as renewing solar reflective paint, keeping outlets clear and repairing cracks early, makes a real difference to life.
Material and system guarantees are available on some specified asphalt systems, and we register them for you where the system allows. Every re-roof carries our written workmanship guarantee, with the length set out in the quote, and insurance-backed options can be discussed. Our lifespan guide compares asphalt with the other systems.
Which towns in Cornwall do we cover?
Mastic asphalt 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 mastic asphalt roofing cost in Cornwall?
£3,550–£6,450 for a 30 m² mastic asphalt roof including scaffold, 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.
Is mastic asphalt the same as tarmac?
No. Both contain bitumen, but mastic asphalt is a dense, voidless mix with fine limestone aggregate, made to be fully waterproof, while road surfacing is a different material.
Can you put felt or rubber over an asphalt roof?
Sometimes, if the asphalt is dry, well bonded and sound, using a compatible system and primer. Liquid membranes are a common choice because they bond well to cleaned asphalt.
How heavy is a mastic asphalt roof?
Considerably heavier than felt, rubber or single-ply, which is why it is usually laid on concrete or strong timber decks. We check the structure before recommending asphalt on any roof.
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