Penarth at a glance
- Postcode districts
- CF64
- Population
- about 23,437 (GeoNames)
- Council area
- Vale of Glamorgan Council
- Building approval
- Vale of Glamorgan Council building control, or a registered building control approver
- Nearest main town
- Cardiff, about 3 miles
- Guide price region
- Wales (−8% on West Midlands rates)
What makes a good extension roof in Penarth?
If you're fitting a new kitchen under an extension in Penarth, that's a good time to replace the roof. It makes sense to rebuild the roof before fitting new units, ceilings and lighting below, and the insulation upgrade makes the room more comfortable all year.
In a town like Penarth, flat roofs are commonly found on 1930s semis with flat-roofed garages and kitchen extensions or newer estates where the first extension roofs are now being replaced. 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.
How much does a new extension roof cost in Penarth?
Guide price in Penarth: £2,600–£4,500 for a 20 m² extension roof in EPDM with a new deck and insulation, including VAT at Wales rates. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM, new deck + insulation | £2,600–£4,500 |
| Extension (20 m²), GRP, new deck + insulation | £2,750–£4,950 |
| Extension (20 m²), EPDM, insulation + 1 rooflight upstand | £2,750–£4,800 |
| Single garage (18 m²), EPDM rubber | £1,450–£2,600 |
Does an extension roof replacement need building regulations?
Usually, yes. An extension roof over a heated room is a thermal element, so replacing most of it typically brings insulation requirements and an approval route.
In England, renovating more than half of the roof means upgrading it towards 0.16 W/m²K where that is technically, functionally and economically feasible. The approval comes from building control or a competent person scheme. A brand-new extension roof is designed to 0.15. Wales usually requires approval for most re-roofing, with a renovation target of 0.16 and a new-extension target of 0.13. Scotland handles this through building standards and the warrant process, and Northern Ireland through district council building control.
Planning is not normally needed to re-cover an extension roof that looks broadly the same afterwards. Turning the roof into a terrace is another matter. We handle building control where the job needs it; see our building regulations page.
What's included?
- Building control handled where needed, and a written workmanship guarantee
- New deck, vapour control layer and warm-roof insulation
- Staged strip-out so the room stays weathertight
- Falls set away from the house wall
Building regulations in Wales
The Welsh Approved Document L applies. Renovating more than half of a roof over a heated room means upgrading it to around 0.16 W/m²K where feasible, and new extension roofs are built to 0.13 W/m²K. Welsh Government guidance is that most re-roofing needs building control approval, so check whenever more than a quarter of a roof is replaced or repaired. We deal with the application as part of the job. More on the rules.
Which nearby areas do we also cover?
Extension and kitchen roofs in Penarth: questions
Do you cover Penarth?
Yes. Penarth is part of our Vale of Glamorgan coverage, including postcode districts CF64. Surveys and roofs are carried out by vetted roofing teams working under S&K Property Investments and Improvement Ltd.
Who checks building regulations for a flat roof in Penarth?
Where the work needs approval it goes to Vale of Glamorgan Council building control, or a registered building control approver. We tell you at the survey whether your job needs it and deal with the paperwork as part of the quote.
How much does a new extension roof cost in Penarth?
£2,600–£4,500 for a 20 m² extension roof in EPDM with a new deck and insulation, at Wales guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Will a new extension roof sit higher than the old one?
Usually, by the thickness of the added insulation. We check the height against the upstairs window sills, door thresholds and wall flashings at survey so everything still works.
Can you keep my existing roof lantern?
Often, if the lantern itself is sound. We lift it, rebuild the kerb, dress the new membrane up the upstand and refit the lantern.