Carmarthen at a glance
- Postcode districts
- SA31
- Population
- about 15,854 (GeoNames)
- Council area
- Carmarthenshire County Council
- Building approval
- Carmarthenshire County Council building control, or a registered building control approver
- Nearest main town
- Llanelli, about 13 miles
- Guide price region
- Wales (−8% on West Midlands rates)
What makes a good extension roof in Carmarthen?
Condensation drives some replacements in Carmarthen. 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.
Around Carmarthen, flat roofs are common on lock-up garage blocks on estates and on 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.
How much does a new extension roof cost in Carmarthen?
For Carmarthen 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 |
Why does water pond or leak where the extension meets the house?
Usually because the fall runs the wrong way, the abutment detail has failed, or the roof has sagged close to the wall. The junction with the house is the most common leak point on an extension roof.
If the roof falls towards the house, or the deck dips near the wall, water sits against the upstand and finds any weakness in the flashing above. Older roofs often have the felt simply turned up the brickwork with no cover flashing, or a flashing that has pulled out of its joint. A patch will not change a fall. We re-firr or use tapered insulation so water runs away from the wall, then form a new upstand, usually 150 mm above the finished roof, with a flashing chased into the mortar joint.
Rooflights and lanterns are the other weak point. A lantern needs a properly built kerb with the membrane dressed up and under its frame. We rebuild rooflight upstands within the roof job; we do not supply the lantern itself. Our guide to ponding water explains the causes in more depth.
What's included?
- Free survey of the roof, abutment and room below
- Building control handled where needed, and a written workmanship guarantee
- New deck, vapour control layer and warm-roof insulation
- New abutment upstand and flashing, plus rebuilt rooflight kerbs
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 Carmarthen: questions
Do you cover Carmarthen?
Yes. Carmarthen is part of our Carmarthenshire coverage, including postcode districts SA31. 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 Carmarthen?
Where the work needs approval it goes to Carmarthenshire County 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 Carmarthen?
£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.
How do I know my extension roof needs replacing rather than repairing?
Repeated leaks, a soft deck, wet insulation or widespread cracking point to replacement. A single defect on a dry, sound roof can usually be repaired.
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.