Cost of Single Storey Extension in Swansea (2026)
If you're looking at single storey extension in Swansea right now, you should be seeing quotes in the £1,530 to £2,720 range per m². That's based on current Swansea contractor rates and the wider UK market. Anything well outside those numbers is worth questioning before you sign.
About single storey extension in Swansea
Swansea is a large city of around 247,000 in Swansea. The housing is mostly Victorian tenements, sandstone terraces and 20th-century estates typical of Scottish and Welsh urban centres. That matters: older properties usually mean more pipework, rewiring and retrofit surprises, while newer builds in districts like SA1, SA2, SA3 tend to be quicker jobs with standardised fittings. Local trade prices sit below the UK average. Lower contractor overheads and shorter distances across Swansea do most of the work.
Welsh trade rates run roughly 10 to 15 percent below the UK average. Cardiff and Newport are fine for supply; rural West Wales, Gwynedd and Snowdonia can see longer lead times plus mileage added in. On renewables work, check for MCS specifically — plenty of firms have CITB and Gas Safe but MCS is a narrower group.
Building jobs are labour-heavy, and materials have moved fast — brick, timber, steel, insulation and board are all 20 to 40 percent up on pre-2022. FMB and TrustMark are your best signposts for a proper builder. On anything bigger than a loft conversion, get a Building Control officer involved from day one; fixing non-compliance later costs a fortune.
Single Storey Extension cost breakdown in Swansea
Simple rear extension with standard finish
Open-plan kitchen extension with bi-fold doors
Wrap-around or glazed extension with lantern roof and structural steels
What affects the price of single storey extension in Swansea?
- Ground conditions and foundation depth
- Glazing ratio (bi-folds, roof lights)
- Kitchen refit included
- Structural steels and knock-through
- Planning permission vs PD
Swansea vs the UK average
Swansea sits in the building & construction market at a cost multiplier of 0.85× the UK national average. That puts Swansea single storey extension prices at £1,530–£2,720 versus the UK average of £1,800–£3,200 per m².
Single Storey Extension cost calculator — Swansea
Estimate based on live 2025 UK trade pricing. Always get 3 written quotes before committing.
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What's typically included in a single storey extension quote
- Foundations and drainage
- Brick and block shell
- Roof and glazing
- First and second fix
- Plaster and decoration
Frequently asked questions
How much does single storey extension cost in Swansea?
Budget £1,530 to £2,720 per m² for single storey extension in Swansea. Prices here are around 15% cheaper than the UK average. What moves a quote inside that range is mostly building contractor day rates in Swansea and the specific material list for your job.
How long does single storey extension take in Swansea?
A straightforward single storey extension job in Swansea runs to 10–16 weeks. You can lose days to things outside the contractor's control — parts on backorder, awkward access, or a firm slotting your job around existing bookings. Ask for a start date and expected finish up front.
What's included in the price of single storey extension in Swansea?
A proper single storey extension quote in Swansea should cover: Foundations and drainage; Brick and block shell; Roof and glazing; First and second fix; Plaster and decoration. If any of those aren't itemised on your quote, push back and ask. A written guarantee with a clear warranty period is reasonable to expect on this kind of work.
Is single storey extension cheaper in Swansea than the UK average?
Single Storey Extension in Swansea runs around 15% cheaper than the UK average. The UK-wide benchmark for this job is £1,800 to £3,200 per m²; Swansea quotes tend to land between £1,530 and £2,720. Handy to know what the average actually looks like before you price round.
Do I need planning permission for single storey extension in Swansea?
Most rear extensions fall under Permitted Development (up to 6m terraced/8m detached with Prior Approval). Side extensions and Article 4 areas require full planning. If the property sits in a conservation area or is listed, ring Swansea Council before you book anything in. It's a free call and saves a world of grief later.
See all single storey extension prices across the UK or browse all tradespeople costs in Swansea.