Caernarfon at a glance
- Postcode districts
- LL55
- Population
- about 9,730 (GeoNames)
- Council area
- Gwynedd Council
- Building approval
- Gwynedd Council building control, or a registered building control approver
- Nearest main town
- Bangor, about 8 miles
- Guide price region
- Wales (−8% on West Midlands rates)
When should a flat roof in Caernarfon be replaced?
A sensible moment to replace a flat roof in Caernarfon is when other work is planned on the house, such as a kitchen refit below, new windows or a loft conversion. Doing the roof first protects the new work, and it is the natural time to upgrade insulation to the level the regulations expect for a renovated roof.
Around Caernarfon, flat roofs are common on low-rise post-war blocks of flats and on shops with flat-roofed rear stores below flats. 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 flat roof replacement cost in Caernarfon?
Guide price in Caernarfon: £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 |
| Single garage (18 m²), torch-on felt | £1,400–£2,400 |
| Extension (20 m²), GRP, new deck + insulation | £2,750–£4,950 |
| Single garage (18 m²), EPDM rubber | £1,450–£2,600 |
Do I need building regulations approval to replace a flat roof?
Often, yes. Replacing the covering of a flat roof over a heated room is usually treated as renovating a thermal element, which brings insulation requirements and, in most cases, approval.
In England, if more than half of that roof is renovated, the whole roof should be upgraded towards a U-value of 0.16 W/m²K for homes (0.18 for non-domestic buildings) where that is technically, functionally and economically feasible, judged against a simple payback of 15 years. Approval comes from building control or self-certification through a registered competent person scheme. Structural changes, or a covering that adds 15% or more to the roof's weight, also need approval.
The other nations differ: most re-roofing in Wales needs approval, Scotland works through building standards and the building warrant, and in Northern Ireland you contact the district council's building control first. An unheated detached garage is not normally a thermal element. Planning permission is not usually needed if the roof looks much the same afterwards, though listed buildings and conservation areas are different. We handle approvals where needed; see building regulations.
What's included?
- New membrane, upstands, edge trims and outlets
- Free survey of the deck, falls, edges and insulation
- Building control handled where needed, plus a written workmanship guarantee
- Fixed written quote listing the full build-up
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?
Flat roof replacement in Caernarfon: questions
Do you cover Caernarfon?
Yes. Caernarfon is part of our Gwynedd coverage, including postcode districts LL55. 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 Caernarfon?
Where the work needs approval it goes to Gwynedd 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 flat roof replacement cost in Caernarfon?
£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.
Is VAT charged on a flat roof replacement?
Yes, roof replacement is standard-rated at 20%, and an insulated replacement is treated as a single supply. Our guide prices already include VAT.
Can you replace just part of a flat roof?
Sometimes, if the rest is sound and dry. Renovating more than half of a roof over a heated room usually brings the whole roof under the insulation rules, so a full replacement can make more sense.