- Price per m²
- £102–£180
- Typical life
- 30–60 years
- Manufacturer guarantees
- 15-year material, up to 25-year system guarantees
- 30 m² roof
- £4,150–£7,500
London at a glance
- Largest towns
- Westminster, Camden, Islington, Haringey
- Postcode areas
- BR, CR, DA, E, EC, EN, HA, IG, KT, N
- Building control
- City of Westminster, London Borough of Camden, London Borough of Islington and 29 other councils
- Neighbouring areas
- Surrey · Hertfordshire · Buckinghamshire · Berkshire
- Guide price region
- London (+20% on West Midlands rates)
How much does mastic asphalt roofing cost in London?
Guide prices including VAT at London 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 | £4,150–£7,500 |
| Localised patch repair | £180–£600 |
| Single garage (18 m²), EPDM rubber | £1,900–£3,350 |
| Extension (20 m²), EPDM, new deck + insulation | £3,350–£5,850 |
Which flat roofs are common in London?
Flat roofs in London sit on shops with flat-roofed stores below flats above, mansard and dormer loft conversions and Victorian and Edwardian terraces with flat-roofed back additions. The Thames basin is one of the drier parts of Britain at roughly 730 mm of rain a year, but summer heat is the bigger test here: dark membranes on south-facing roofs swing a long way in temperature. 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 London the application goes to City of Westminster, London Borough of Camden, London Borough of Islington and 29 other councils. More on the rules.
Should an old asphalt roof be repaired, overlaid or replaced, especially on a heritage building?
If the asphalt is sound apart from local cracks or blisters, repair it; if it is crazed and tired but dry and well bonded, consider an overlay; if it is leaking widely, sitting on a wet or failing deck, or full of trapped moisture, replace it. A survey, sometimes with a leak trace, tells you which applies.
- Repairs: blisters are cut out, cracks opened up and fresh asphalt worked in by a specialist, so the repair fuses with the existing roof.
- Overlay: a compatible system, often a reinforced liquid membrane, is bonded over the old asphalt after cleaning and priming. This keeps the old asphalt as a solid base and avoids heavy strip-out.
- Replacement: the old asphalt is broken out and the roof rebuilt, either in new asphalt or in another system the structure can carry, with insulation where required.
On heritage and older buildings, matching the original material and detailing often matters as much as waterproofing. New asphalt skirtings and aprons can follow the existing lines, and any change of material on a listed building should be agreed with the conservation officer before work starts.
Asphalt work is a specialist trade. It needs mixers or boilers on site, trained asphalters and strict hot-works control, so we plan these jobs around access, the building's occupants and the weather.
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 London do we cover?
- Westminster
- Camden
- Islington
- Haringey
- Hounslow
- Barnet
- Bexley
- Lambeth
- Croydon
- Havering
- Lewisham
- Redbridge
- Southwark
- Bromley
- Ealing
- Hammersmith and Fulham
- Harrow
- Kensington and Chelsea
- Barking and Dagenham
- Brent
- Greenwich
- Hillingdon
- Kingston upon Thames
- Richmond upon Thames
- Sutton
- Waltham Forest
- Enfield
- Hackney
- Newham
- Tower Hamlets
- Merton
- Wandsworth
Mastic asphalt roofing in London: questions
Which towns in London do you cover?
All of London. 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 London?
£4,150–£7,500 for a 30 m² mastic asphalt roof including scaffold, at London 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 London?
It depends on where the roof is: in London that's City of Westminster, London Borough of Camden, London Borough of Islington and 29 other councils. 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.
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.
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.
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.
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