A double-storey extension adds two floors of new space to your house in one build, typically a larger kitchen or living room downstairs with an extra bedroom, bathroom or en-suite above, sharing one set of foundations and one roof.
For a homeowner in Llanelli, planning a double-storey extension tends to begin with two questions: what will it cost, and how disruptive will it be? Our guide range is £55,000–£110,000 including VAT, and a typical job runs to 14–22 weeks on site. Both numbers firm up once we have seen the property, measured up and agreed exactly what is included.
- Guide price
- £55,000–£110,000 inc VAT
- Time on site
- 14–22 weeks on site
- Postcodes
- SA15
- Planning rules
- Wales
- Local area
- Carmarthenshire
- Survey
- Free, with a written quote
What should you budget for a double-storey extension in Llanelli?
Below is a breakdown of typical costs for a double-storey extension in Llanelli. Because rates in Wales are about 8% below the national guide, the overall guide comes to £55,000–£110,000, including VAT. Size, materials and access move the figure, and a free-of-charge survey settles it.
| Type of job | What it usually involves | Guide in Llanelli |
|---|---|---|
| Small (15–20m² total) | A compact rear or side extension adding a small room on each floor. | £37,000–£60,000 |
| Typical (30–40m² total) | A larger kitchen or living room below with a double bedroom or en-suite above. | £55,000–£110,000 |
| Large (50m² plus total) | Wide or deep extensions, often with a new bathroom, steelwork and high-spec glazing. | £92,000–£166,000 |
Expect these to shape the final quote:
- How the new roof joins the existing roof
- Bathrooms, en-suites and plumbing on the upper floor
- Foundation depth, ground conditions and drains to divert
- Scaffolding duration, access and the level of finishes
What do you get?
- Groundworks, foundations and below-ground drainage
- Insulated cavity walls with brick or render to match the house
- First-floor joists, stud walls and new openings upstairs
- Roof structure tied into the existing roof, tiled to match
- Electrics, plumbing and heating by qualified trades, with certificates
- Building control inspections and completion certificate
What are homes like around Llanelli?
Dyfed covers Carmarthenshire, Ceredigion and Pembrokeshire. Stone cottages and farmhouses under slate roofs are common, often rendered or colour-washed, as in Tenby's brightly painted terraces. Llanelli has Victorian industrial terraces, Aberystwyth and Carmarthen have Georgian and Victorian centres, and bungalows and newer estates surround most towns.
Atlantic weather brings strong winds, driving rain and salt to the coast, so exposure ratings matter when specifying render and pointing.
If your house in Llanelli fits one of these patterns, it helps us anticipate what a double-storey extension will involve, though we always confirm the details on site.
Planning and building rules in Llanelli
Homes in Llanelli come under the regulations for Wales, summarised below. We don't rely on general rules alone: we confirm the position for your address with the council before a quote goes out.
In Wales, two-storey extensions are tightly limited under permitted development, including distance to the rear boundary, so most need planning permission.
Building Regulations approval is needed in Wales, and the Party Wall etc. Act 1996 applies to work on or near shared walls.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
How does the job run?
We look at the job
First, someone visits your home in Llanelli to see the space, take measurements and note anything that could affect the work, such as access or the condition of what is there. There is no charge for this visit.
Quote in writing
Next you receive a written quote with a fixed price for the agreed specification. It lists what is included, what is not, and how payments are staged, so you can compare it properly.
Booking the work
We handle the paperwork side: checking whether planning permission or building control approval is needed, submitting applications where they are, and scheduling the trades and materials around your dates.
Finish and handover
During the work we protect the areas around it and tidy up at the end of each day. Once complete, we check the finish, remove our materials and hand over paperwork such as building control sign-off where it applies.
What you can expect from us
Double-storey extensions in Llanelli: questions
Can the new upstairs room have its own bathroom?
A new upstairs room can usually have an en-suite, provided waste pipes can reach the soil stack or a new one can be installed. Running the waste pipe to the right falls is the main design question, and a pumped system is an option where gravity will not work. We plan bathroom positions at the design stage so pipes, ventilation and insulation are built in rather than added later.
Is a double-storey extension better value than single-storey?
A double-storey extension usually gives better value per square metre than a single-storey one, because the same foundations and roof serve twice the floor area. The overall cost is higher, and planning can be harder because of the effect on neighbours. If you might want an extra bedroom later, building both floors now avoids a second round of disruption and scaffolding.
Which postcodes in Llanelli do you cover?
We cover SA15, along with the rest of Dyfed. If your postcode is not listed, get in touch anyway: our coverage is UK-wide, and we can usually arrange a survey wherever you live. Enter your postcode in the guide-price tool or contact form and we will confirm.
How much will a double-storey extension cost in Llanelli?
As a guide, expect to pay £55,000–£110,000 including VAT for a double-storey extension in Llanelli. That range is adjusted for Wales, which runs about 8% below the national guide. Where your project lands depends on size, materials, access and the condition of what is already there. We confirm a fixed price in writing after a free survey of your home.
Can we live at home while it is built?
Most families stay at home during a double-storey extension. The new structure is built outside first, and we only break through into the existing rooms near the end, usually one floor at a time. Upstairs, this may mean a bedroom is out of use for a week or two. We fit dust screens, protect floors and stairs, and plan any time without water or power in advance.
Also covering areas around Llanelli
Llanelli and its SA15 postcodes are part of our coverage. Homeowners in Gorseinon, Swansea and Ammanford can also book a free survey with us and receive a written price for their job.