- Price per m²
- £83–£129
- Typical life
- 10–25+ years by product
- Manufacturer guarantees
- 10, 15 or 20-year guarantees by named system
- Typical garage roof
- £1,900–£3,000
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 a liquid-applied roof 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 |
|---|---|
| Single garage (18 m²), liquid-applied | £1,900–£3,000 |
| Balcony (12 m²), liquid-applied, scaffold | £1,750–£3,000 |
| 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 terraced streets with flat-roofed rear kitchens and bathrooms, bungalows with flat-roofed side extensions and dormers and 1960s and 1970s link-detached houses with flat-roofed garages and porches. 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.
Can a liquid roof go over my existing roof, and what preparation is needed?
Yes, if the existing roof is dry, firmly bonded and sitting on a sound deck. A liquid membrane is only as good as what lies beneath it, so we test the old roof before agreeing to overlay it.
At survey we check for:
- Trapped moisture: soft spots, blisters or wet insulation mean the roof should be stripped, because water sealed in will cause new blisters and decay.
- Deck condition: any sponginess or deflection needs repair first.
- Adhesion: on felt and asphalt, loose areas are cut out and patched, and the existing surface must take the primer properly.
- Falls and ponding: a coating follows the roof as it is. If water ponds now, it will pond on the new surface too unless the falls are corrected.
Preparation then follows: loose chippings removed, the surface cleaned and left to dry, blisters cut back and repaired, cracks filled, and the right primer applied. On older felt, mineral surfaces may need extra cleaning to give a good bond. Where the tests fail, we say so plainly and quote for a strip and re-roof. Read more on ponding water.
How long does a liquid-applied roof last, and how is it guaranteed?
Cold liquid-applied roofs typically last 10 to 25 years or more, depending on the product and the thickness applied. One reinforced system has a BBA assessment of over 25 years, while lighter coatings designed to extend an existing roof sit at the lower end of the range.
Because life varies so much by product, it pays to know exactly what is being applied. Your quote should name the system, the reinforcement and the build-up.
Manufacturer guarantees are often tied to a named system, with lengths such as 10, 15 or 20 years depending on the specification, and some require registration or an approved applicator. We handle that registration where the system permits it. Every re-roof also carries our written workmanship guarantee, with the length set out in the quote, and you can ask about insurance-backed options. A BBA certificate is a product assessment, not a guarantee; our guarantees guide explains the difference.
Which towns in Monmouthshire do we cover?
Liquid-applied 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 a liquid-applied roof cost in Monmouthshire?
£1,900–£3,000 for a typical 18 m² garage roof in a liquid-applied system, 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 liquid roofing stop a leak on a flat roof?
It can, if the leak is at a detail or the membrane is worn but the roof beneath is sound. If water has soaked the insulation or deck, coating over it will not cure the problem.
Is liquid roofing good for balconies?
Often, yes. It forms neatly around railings, door thresholds and drains, and some systems take foot traffic. A new balcony or roof terrace generally needs planning permission, so check before converting a roof.
Does a liquid roof smell when it is applied?
Some systems, particularly PMMA, have a strong odour during application, while many polyurethane and water-based products are milder. We tell you what to expect and plan around windows and vents.
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