How Much Does a Single Storey Extension Cost in 2026?

The Real Numbers

How Much Does a Single Storey Extension Cost in 2026? matters most when a homeowner is close to making a decision and does not want a vague quote, soft assumption, or missing line item to become an expensive problem later.

I review extension quotes every week. Here's what homeowners are actually paying in 2026.

Average Costs by Size

Small (15-20 sqm): £40,000 - £55,000 Medium (20-30 sqm): £55,000 - £80,000 Large (30-40 sqm): £80,000 - £110,000

Cost Per Square Metre

For a standard specification single storey extension:

• Budget build: £1,800 - £2,200/sqm.
• Mid-range: £2,200 - £2,800/sqm.
• High spec: £2,800 - £3,500/sqm.

What Affects the Price?

Foundations — Clay soil or trees nearby can add £10,000+ Roof type — Flat roofs cheaper than pitched Glazing — Bifolds vs French doors: £3,000-8,000 difference Kitchen/bathroom — Adding these increases cost significantly Location — London & South East 20-30% higher than Midlands

What's Included (And What Isn't)

A typical quote should include:

• Groundworks and foundations.
• Structure (walls, roof, insulation).
• Electrics and plumbing.
• Plastering and decoration.
• Flooring (usually not tiling).
• Building control fees.

Usually NOT included:

• Kitchen units and appliances.
• Bathroom fixtures.
• Landscaping.
• Architect fees.
• Party wall fees.

Regional Variations (2026)

| Region | Cost/sqm | |--------|----------| | London | £3,200-4,500 | | South East | £2,800-3,800 | | Midlands | £2,200-3,000 | | North | £2,000-2,800 | | Wales | £1,900-2,600 |

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About Single storey extension cost 2026

Understanding single storey extension cost 2026 is crucial for any homeowner planning an extension. At The Building Guys, we review single storey extension cost 2026 issues daily and can help you avoid common mistakes related to single storey extension cost 2026.

Frequently Asked Questions

How much does single storey extension cost 2026 typically cost?

Costs vary significantly based on your location, specification, and site conditions. In Derbyshire, expect to pay £1,800-£2,500 per square metre for a standard extension. Always get at least 3 quotes and have them independently reviewed.

How long does single storey extension cost 2026 take?

A typical single-storey extension takes 10-14 weeks from breaking ground to completion. Planning permission adds 8-12 weeks upfront. Factor in weather delays and material availability.

Do I need planning permission?

Many extensions fall under Permitted Development rights, but this depends on your property type, location, and the extension size. Conservation areas and listed buildings have stricter rules. Always check with your local authority before starting work.

Should I get an independent review?

Absolutely. An independent review costs a fraction of fixing problems later. We typically save homeowners thousands by catching issues before they become expensive mistakes.

Next Step

If you want help applying this to your own project, use the right route below.

• Start with [Quick Review](/quick-review) if you want a fast first check.
• Use [Builder Quote Review](/builder-quote-review) if you already have a quote in hand.
• See the [Sample Report](/sample-report) if you want proof before you buy.