- 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
Dorset at a glance
How much does mastic asphalt roofing cost in Dorset?
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 Dorset?
Flat roofs in Dorset sit on low-rise post-war blocks of flats, 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 Dorset the application goes to BCP Council and Dorset Council. More on the rules.
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.
Is mastic asphalt still a good choice, or should I switch systems?
Mastic asphalt is still a good choice on concrete roofs, heritage and older buildings, and roofs that carry heavy foot traffic or plant. On lightweight timber roofs, garages and most modern extensions, another system is usually more practical.
Benefits: very long typical life; jointless and fully bonded; takes foot traffic well, especially with a paving finish; matches the original roof on many older buildings; local repairs blend into the existing surface.
Drawbacks: heavy, so the structure must be able to carry it; higher cost; needs specialist labour and hot works with molten material; can crack in cold if not well maintained, and softens in strong sun without a reflective finish.
If the structure is lightweight or the budget tight, torch-on felt or EPDM are common replacements. A compatible liquid-applied system can sometimes be laid over sound asphalt. On larger roofs, single-ply may be considered, and GRP suits smaller roofs needing a hard finish. Our repair or replace guide helps with the decision.
Which towns in Dorset do we cover?
Mastic asphalt roofing in Dorset: questions
Which towns in Dorset do you cover?
All of Dorset. 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 Dorset?
£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 postcode areas do you cover in Dorset?
All of Dorset, including the BH, DT postcode areas. Send your full postcode and we'll confirm.
Can I repair a mastic asphalt roof myself?
Not properly. Lasting asphalt repairs use fresh hot asphalt, which needs specialist equipment, training and hot-works control. Cold-applied sealants can hold a small leak for a short time, but they are a stopgap until a specialist repair.
Why are mastic asphalt roofs painted silver or white?
The reflective coating keeps the asphalt cooler in sun, reducing softening and slowing the surface ageing that leads to crazing. It usually needs renewing every few years as part of maintenance.
Why is my asphalt roof cracking?
Asphalt typically cracks as it ages and becomes brittle from sun exposure, or where the building moves at skirtings and junctions. A solar reflective paint and early repairs help slow it down.
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