- 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
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 mastic asphalt roofing 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 |
|---|---|
| Mastic asphalt roof (30 m²), scaffold | £3,200–£5,750 |
| Localised patch repair | £140–£460 |
| 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 shops with flat-roofed rear stores below 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 Monmouthshire the application goes to Monmouthshire County Council. More on the rules.
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.
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 Monmouthshire do we cover?
Mastic asphalt 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 mastic asphalt roofing cost in Monmouthshire?
£3,200–£5,750 for a 30 m² mastic asphalt roof including scaffold, 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 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.
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.
Is mastic asphalt suitable for a balcony or terrace?
Yes, asphalt is traditionally used on terraces and walkways because it takes foot traffic well, often with paving on top. A new balcony or terrace generally needs planning permission, so check before converting a roof.
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