How Much Does a House Extension Cost in Taunton? (2026 Price Guide)
Planning a house extension in Taunton or Somerset? This guide gives you realistic, up-to-date cost information from an experienced local builder — so you can plan your budget with confidence.
House extension costs vary considerably depending on the type of extension, its size, the specification you choose, and a range of site-specific factors. As Taunton builders with over 20 years of experience, we're frequently asked by homeowners in Somerset what they should expect to pay. This guide provides honest, realistic figures based on projects we complete in the local area.
Average House Extension Costs per m² in Somerset (2026)
| Extension Type | Standard (per m²) | High Spec (per m²) |
|---|---|---|
| Single Storey Rear | £1,500–£2,200 | £2,000–£2,800+ |
| Double Storey | £1,200–£1,800 | £1,600–£2,400+ |
| Side Return | £1,800–£2,500 | £2,200–£3,000+ |
| Wrap-Around | £1,500–£2,200 | £2,000–£2,800+ |
| Garage Conversion | £800–£1,400 | £1,200–£2,000+ |
Note: These costs include all labour and materials for a typical extension, but exclude kitchen or bathroom fitting, which is priced separately.
Single Storey Extension Costs Taunton
A single storey rear extension is the most common type we build across Taunton and Somerset. For a typical 20m² kitchen-diner extension at a standard specification, expect to pay £30,000–£44,000 for the structural build. Add kitchen installation and you're typically looking at £40,000–£65,000 in total for a fully fitted kitchen extension.
At a higher specification — with bi-fold or sliding doors, premium floor finishes, plastered ceilings with recessed lighting and better quality windows — costs move to £40,000–£56,000 for the structural shell, with total costs including kitchen typically £55,000–£80,000+.
Double Storey Extension Costs Somerset
Double storey extensions are excellent value because you're adding two floors for significantly less than the cost of two separate extensions — the foundations and roof are shared. A typical 40m² double storey extension (20m² per floor) in Somerset typically costs:
- Standard specification: £48,000–£72,000
- High specification: £64,000–£96,000+
- Including kitchen and en-suite: add £15,000–£35,000
What Affects House Extension Costs?
Several key factors influence the final cost of your extension beyond the basic m² rate:
- Ground conditions: Poor ground bearing capacity or high water tables require deeper or reinforced foundations, adding cost.
- Site access: Restricted access for deliveries and skips can increase costs, particularly in town centre or narrow road locations.
- Planning: Full planning applications add costs for architect drawings and planning fees (typically £2,000–£5,000). Many extensions are Permitted Development.
- Structural engineering: Open plan layouts requiring steel beams add £1,500–£5,000 for the engineering design and steelwork supply.
- Windows and doors: Standard casement windows are included in basic costs. Bi-fold doors, roof lights and aluminium systems add £3,000–£15,000.
- Specification: Underfloor heating, premium tiles, bespoke joinery and high-end appliances all add to the total cost.
Getting an Accurate Quote in Taunton
The most reliable way to understand what your extension will cost is to get a detailed, itemised quote from a reputable local builder. Be wary of very low quotes that may not account for building regulations, VAT, or the full scope of work — or builders who quote a rate per m² without visiting the site.
At Taunton Construction, we visit every site before quoting, assess the ground conditions, discuss your ideas in detail, and provide a fixed-price contract that covers all labour, materials and building regulations fees. There are no hidden costs.