How Much Does a Home Extension Cost in Northamptonshire?

A home extension is one of the most effective ways to create extra space without the stress of moving. Whether you want a larger kitchen, an extra bedroom, a home office or a full two-storey extension, understanding the costs involved helps you plan your project with confidence.

At L F Builders Ltd, we have more than 30 years’ experience delivering single-storey, double-storey and wrap-around extensions across Kettering, Corby, Wellingborough, Northampton and the surrounding Northamptonshire villages. Below is a clear, practical guide to what homeowners can expect.

Typical Cost of a Home Extension in Northamptonshire

The cost of an extension depends on size, design, materials and structural requirements, but most projects in Northamptonshire fall within these ranges:

Single-Storey Extension

£1,800 – £2,500 per m²

Suitable for:• Kitchen extensions• Utility rooms• Rear/side extensions• Small open-plan living spaces

Double-Storey Extension

£1,600 – £2,200 per m² (per floor)

These offer excellent value for money because the foundations and roof are shared across two levels. Ideal for adding multiple bedrooms, bathrooms or extra living space.

Small Extensions / Porches

£8,000 – £25,000

Useful for cloakrooms, small utility spaces or front porches.

Large Wrap-Around Extensions

£60,000 – £120,000+

Costs vary depending on structural complexity, steelwork requirements and how much internal remodelling is needed.

What Affects the Cost?

1. Size and complexity

Bigger spaces, unusual angles, extensive steel beams or significant structural changes increase both labour and material costs.

2. Foundations and ground conditions

Northamptonshire clay soils can influence the type and depth of foundations required.

3. Roofing style

Flat roofs are usually more affordable; pitched roofs cost more but offer better longevity and appearance.

4. Windows, doors and glazing

Bi-folding or sliding doors, skylights and structural glazing can increase the budget but transform the final look.

5. Internal finishes

Kitchens, bathrooms, underfloor heating and electrical upgrades vary widely in price depending on specification.

6. Planning permission

Many extensions fall under Permitted Development, but if planning is required, allow time and additional fees.

Do Northamptonshire Home Extensions Need Planning Permission?

Some do, some don’t.Many small to medium-sized rear or side extensions fall under Permitted Development Rights, but the rules are detailed and depend on:

• Your property type (detached, semi, terrace)• Whether previous extensions exist• Distance to boundaries• Overall footprint and height

As a long-established Northamptonshire building company, we can advise early in the process and work alongside your architect or designer to ensure compliance.

How Long Does a Home Extension Typically Take?

Approximate timelines:

• Small single-storey: 8–12 weeks• Medium single-storey: 12–16 weeks• Double-storey: 16–24 weeks• Large wrap-around: 20–30 weeks

Weather, supply chains and design changes can affect schedules, but careful planning and ongoing communication help keep projects on track.

Why Costs Vary Between Builders

Different quotes often reflect differences in:

• Quality of workmanship• Materials included• Structural integrity (e.g., correct steel sizes)• Compliance with building regulations• Clear vs vague allowances for kitchens, bathrooms and finishes• Experience with local planning and building control

At L F Builders Ltd, all work is completed in full compliance with UK building regulations and overseen by qualified professionals, ensuring long-lasting, high-quality results.

How to Control Your Extension Budget

• Decide early on your must-have features• Allow a 10–15% contingency• Choose materials within your budget• Finalise designs before work begins• Work with an experienced local builder who provides clear itemised quotes

Get a Quote for Your Northamptonshire Home Extension

If you are considering extending your home in Kettering, Corby, Wellingborough, Northampton or the surrounding villages, L F Builders Ltd can provide clear advice, transparent pricing and high-quality workmanship from start to finish.

Contact us today to arrange a free, no-obligation site visit.