If you’re thinking about adding extra space to your home in East Sussex, one of the first questions you’ll have is: how much will it cost? Whether you’re considering a rear kitchen extension in Lewes, a double-storey build in Eastbourne, or a wraparound in Hastings, understanding the costs involved is key to planning your project confidently.
At SDS Builders, we’ve helped hundreds of homeowners in and around East Sussex transform their properties with high-quality, value-adding extensions. In this guide, we’ll walk you through the main factors that affect the cost of a house extension and give you realistic estimates to help you budget.
Average Cost of a House Extension in East Sussex
As a general guide, you can expect to pay:
- £1,800 – £2,500 per m² for a single-storey extension
- £2,400 – £3,200 per m² for a double-storey extension
So for a 20m² single-storey rear extension, the cost could range from £36,000 to £50,000, depending on the level of finish and complexity.
These are ballpark figures. Your final cost will depend on a number of variables, including the condition of the existing property, materials used, access to the site, and any planning or structural requirements.
What Influences the Cost of a House Extension?
Several key factors affect the total price of an extension project in East Sussex:
1. Type of Extension
- Rear or side return extensions are generally more straightforward and affordable.
- Wraparound or double-storey extensions require more materials and labour, increasing the cost.
2. Size and Layout
- Larger builds naturally cost more, but economies of scale can apply.
- Open-plan layouts with steel beams or bifold doors will increase your budget.
3. Quality of Finish
- Standard vs high-spec kitchens, flooring, lighting, glazing – all make a big difference.
4. Planning and Permissions
- If your project falls outside permitted development, you’ll need planning approval.
- Structural calculations, architectural drawings, and building regulations will also add to the total.
5. Site Conditions
- Poor ground conditions, difficult access, or listed building status can increase costs.
What’s Included in an SDS Builders Extension?
When you work with SDS Builders, we provide a comprehensive, end-to-end service, including:
- Site survey and quote
- Architectural design and planning support
- Structural engineering and building control
- Project management and scheduling
- Skilled trades: groundwork, brickwork, electrics, plumbing, roofing
- Internal finishes to your chosen spec
We manage the entire build from start to finish – giving you peace of mind and a seamless experience.
Why Choose SDS Builders for Your House Extension in East Sussex?
Over 20 years’ experience across Sussex and Surrey
Fully insured and accredited team
Local knowledge of planning regulations and building control
Transparent pricing with no hidden extras
Dedicated project manager for every build
Excellent reviews and referrals from satisfied clients
Whether you’re extending for more space, better light, or added property value – we’re here to help you make it happen.
Recent Project: Kitchen Extension in Uckfield (placeholder)
We recently completed a bright and modern 25m² kitchen-diner extension for a family in Uckfield. The build included underfloor heating, aluminium bifold doors, and a large roof lantern – all delivered on time and on budget.
[Add photos/testimonial here if available]
Ready to Plan Your House Extension?
Speak to our expert team today and get a free, no-obligation quote tailored to your East Sussex property.
Call us now or Request a quote online
FAQs: House Extension Costs in East Sussex
How long does it take to build a house extension?
Most single-storey extensions take around 10–14 weeks, depending on the complexity and weather conditions.
Do I need planning permission?
Many extensions fall under permitted development, but this depends on size and location. We can advise you during the consultation phase.
Can I live in my home during the build?
Yes, in most cases clients can remain in their homes, though some disruption is to be expected.
Will you handle building control and inspections?
Absolutely – we manage all aspects of building regulations compliance and liaise with local building control.
Do you offer fixed-price quotes?
Yes, once plans are agreed and the scope is finalised, we offer a detailed fixed-price quote so you can budget with confidence.