Thinking about adding more space to your home? Whether it's a growing family, a new kitchen-diner, or an office for working from home, house extensions are a brilliant solution.

But the big question is… how much does a house extension cost in Salisbury?

At Complete Construction Salisbury, we've put together this honest, practical guide to help you understand what's involved, how the costs break down, and what to expect from your project.

Average Cost of a House Extension in Salisbury

Let's start with some ballpark figures:

—Single-storey extension: £1,800 – £2,800 per m²
—Double-storey extension: £2,500 – £3,000 per m² (the second floor is cheaper than the first)
—Small rear extension (15m²): Around £30,000 – £45,000+
—Larger wrap-around extension (40m²+): £75,000 – £120,000+

These are guide prices for the build phase only, and costs will vary depending on the size, design, complexity, materials, and ground conditions.

What Affects the Cost of an Extension?

Size and Layout

Naturally, the bigger the extension, the more expensive it is — but costs don't scale perfectly. Larger spaces often work out cheaper per square metre.

Single vs. Double Storey

A double-storey extension doesn't double the price. The foundations and roof are the big-ticket items, so adding an extra floor often costs 30–50% more, not 100%.

Type of Rooms

Kitchens and bathrooms cost more due to plumbing, electrics, and fittings. A basic living room or bedroom extension costs less by comparison.

Ground Conditions and Foundations

This is where surprises happen. Salisbury has a mix of soil types. If we hit poor ground, tree roots, or need piling, foundation costs can rise significantly.

Finishing and Fittings

High-end bi-fold doors, custom glazing, designer kitchens — it all adds up.

Do I Need Planning Permission?

Not always. Some extensions fall under permitted development rights, meaning you don't need full planning permission. However, rules depend on:

—Size of the extension
—Distance from boundaries
—Previous extensions or alterations

Tip: We always advise checking first. As part of our service, Complete Construction Salisbury helps handle the planning process.

What's Included in the Price?

When you work with Complete Construction Salisbury, we include:

—Full project management
—Groundworks and foundations
—Brickwork, roofing, windows, and doors
—Insulation and plastering
—Plumbing and electrics (if required)
—Finishing ready for decoration

Hidden Costs to Watch For

—Architectural drawings and planning fees: £500 – £2,500+
—Structural engineer reports: £500 – £1,500
—Planning permission fees (if required): Around £206
—Building control fees: £600 – £1,000+
—Kitchens, bathrooms, flooring, and decorating: Varies massively depending on your choices

Why Choose Us for Your Extension?

We're not just builders – we're your local, trusted partners. With decades of experience in Salisbury and Wiltshire, we pride ourselves on delivering high-quality work with clear, transparent pricing and excellent communication from start to finish.

Check out our services and our portfolio for examples of our recent work.

Next Steps – Let's Talk About Your Project!

Ready to explore an extension for your home? Contact our team for a free, no-obligation chat about your ideas, your budget, and how we can help.

How Much Does a House Extension Cost in Salisbury? (2025 Guide)