Mastic asphalt roofing across Caerphilly

Price per m²

£78–£138

Typical life

30–60 years

Manufacturer guarantees

15-year material, up to 25-year system guarantees

30 m² roof

£3,200–£5,750

How much does mastic asphalt roofing cost in Caerphilly?

Guide prices including VAT at Wales rates. The fixed price comes after a free survey for new and replacement roofs.

Which flat roofs are common in Caerphilly?

Flat roofs in Caerphilly sit on low-rise post-war blocks of flats, 1930s semis with flat-roofed garages and kitchen extensions and bungalows with flat-roofed side extensions and dormers. 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 Caerphilly the application goes to Caerphilly County Borough Council. 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.

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.

Which towns in Caerphilly do we cover?

• Caerphilly
• Risca
• Gelligaer
• Blackwood
• Bargoed
• Abercarn

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