Llantwit Major at a glance
- Postcode districts
- CF61
- Population
- about 14,384 (GeoNames)
- Council area
- Vale of Glamorgan Council
- Building approval
- Vale of Glamorgan Council building control, or a registered building control approver
- Nearest main town
- Bridgend, about 8 miles
- Guide price region
- Wales (−8% on West Midlands rates)
What makes a good extension roof in Llantwit Major?
Condensation drives some replacements in Llantwit Major. Older extension roofs were often built cold, with insulation between the joists and no reliable vapour control. Warm air from the kitchen reaches the cold deck, moisture builds up and the timber suffers. A warm roof deals with the cause, not just the stain.
Llantwit Major's flat roofs are mostly on newer estates where the first extension roofs are now being replaced, with plenty on terraced streets with flat-roofed rear kitchens and bathrooms too. 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 Llantwit Major?
For Llantwit Major we use Wales rates: £2,600–£4,500 is the guide for a 20 m² extension roof in EPDM with a new deck and insulation, VAT included. 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?
- Falls set away from the house wall
- Free survey of the roof, abutment and room below
- New deck, vapour control layer and warm-roof insulation
- Staged strip-out so the room stays weathertight
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 Llantwit Major: questions
Do you cover Llantwit Major?
Yes. Llantwit Major is part of our Vale of Glamorgan coverage, including postcode districts CF61. 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 Llantwit Major?
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 Llantwit Major?
£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.
Is EPDM or GRP better for a kitchen extension?
Neither is better in every case. EPDM suits simple rectangular roofs with few details, while GRP is often chosen where there are rooflights, corners or occasional foot traffic.