Double-Storey Extensions in South Wales
A double-storey extension delivers far more value per pound than a single-storey because you get two floors of new space for only marginally more groundwork and roofing. Typically that means a bigger kitchen or lounge downstairs and an extra bedroom (often with en-suite) upstairs. We handle full design-and-build including planning applications where required. Most two-storey extensions complete in 14–22 weeks.
Benefits
- Two Floors of New Space: Roughly double the m² for only 30–40% more cost than a single-storey of the same footprint.
- Adds a Bedroom & Bathroom: Most clients add a master bedroom with en-suite upstairs and bigger living space downstairs.
- Highest ROI: Two-storey extensions consistently deliver the best resale return of any home improvement.
- Design-and-Build Service: Architect, structural engineer, Building Regs and the build — all under one roof.
- Fixed Written Quote: Detailed itemised pricing with stage payments — no surprise costs.
- Matched to Existing House: Brickwork, roofline and window style carefully matched so the extension looks original.
Our double-storey extensions range
- Rear Double-Storey Extension: Extend straight back over two floors — most common on semis and detached houses.
- Side Double-Storey Extension: Fill in a side return or driveway with a full two-storey side build.
- Wrap-Around Double-Storey Extension: L-shaped two-storey extension combining rear and side — maximum impact.
- Over-Garage Double-Storey: Add a bedroom or office over an existing single-storey garage.
Frequently Asked Questions
Do I need planning permission for a double-storey extension?
Yes — two-storey extensions almost always require a full planning application. We handle the entire process, from drawings to submission and conditions discharge.
How long does a double-storey extension take?
Most two-storey extensions are completed in 14–22 weeks from groundworks to handover, depending on size and complexity.
How much does a double-storey extension cost?
Typically £2,200–£3,200 per m² of new floor area — a 40 m² (20 m² over two floors) extension is usually £85,000–£130,000. Fixed quotes after survey.
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