How Much Does a Home Extension Cost in Eastbourne? 2026 Price Guide

Planning an extension to your Eastbourne home starts with one essential question: how much will it cost? Understanding realistic budget figures before approaching builders helps you plan finances sensibly, compare quotes meaningfully, and avoid wasting time on projects beyond your means.

As builders who have completed extensions across Eastbourne and East Sussex for years, we know that national estimates often miss the mark for local pricing. This guide provides honest, current figures for extension costs in Eastbourne in 2026, explains what affects pricing, and helps you budget realistically for your project.

Extension Costs at a Glance: 2026 Prices

For a quality extension in Eastbourne built to a good standard with proper foundations, insulation, electrics, and plastering, expect to pay approximately £1,750 to £2,500 per square metre. This range reflects differences in specification, complexity, and finish quality.

In practical terms, a small single storey rear extension of around 15 square metres typically costs £28,000 to £42,000. A medium single storey extension of 20-25 square metres runs between £38,000 and £58,000. A larger single storey extension of 30-40 square metres ranges from £55,000 to £95,000. Double storey extensions typically cost £1,900 to £2,700 per square metre, with a 30 square metre double storey project running £58,000 to £82,000.

These figures include the building work itself: foundations, walls, roof, windows, doors, insulation, electrics, plastering, and basic decoration. They assume standard ground conditions and straightforward site access. They do not include kitchens, bathrooms, high-end finishes, or extensive landscaping, which add to the overall project cost.

What Affects Extension Costs in Eastbourne

The wide price range exists because no two extensions are identical. Understanding what drives costs helps you interpret quotes and make informed decisions about where to invest your budget.

Size and Scale

Larger extensions cost more overall but typically less per square metre. Fixed costs like groundwork, scaffolding, and project management spread across more floor area. A 30 square metre extension rarely costs twice as much as a 15 square metre one. However, bigger projects require more materials, more labour hours, and longer timelines, so the absolute cost increases even as the rate per square metre decreases.

Single vs Double Storey

Double storey extensions deliver more space for your money because the expensive elements, foundations and roof, serve two floors rather than one. Adding a second storey typically costs 50-70 percent more than a single storey extension while doubling your floor space. If you need significant additional accommodation and your property suits it, going up as well as out often makes financial sense. Many Eastbourne semi-detached and detached homes, particularly in areas like Willingdon, Old Town, and Langney, have excellent potential for double storey rear extensions.

Specification and Finishes

The quality of materials and finishes dramatically affects costs. Standard uPVC windows, basic kitchens, and builder-grade flooring sit at the lower end. Aluminium bi-fold doors, underfloor heating, bespoke joinery, and high-end tiles push costs significantly higher. A basic extension might cost £1,750 per square metre while a high-specification build with premium finishes could reach £3,000 or more. Decide early where quality matters most to you and allocate budget accordingly.

Structural Complexity

Simple rectangular extensions with standard pitched or flat roofs cost less than complex designs with multiple corners, varying roof heights, or structural glazing. Opening up your existing house with large structural spans requires steel beams and associated engineering, adding £2,000 to £8,000 depending on the span and load. Vaulted ceilings, roof lanterns, and extensive glazing all add cost compared to conventional construction.

Ground Conditions

Eastbourne sits on varied geology, with chalk downland to the west and different conditions across the town. Properties on sloping sites, common in areas like Meads and the upper parts of Old Town, may require more extensive groundwork and retaining structures. Clay soils in some areas affect foundation design, particularly if trees sit close to your extension site. Coastal properties may face additional considerations around ground stability. Most Eastbourne properties present no unusual challenges, but unexpected ground conditions can add £2,500 to £10,000 to a project. We assess ground conditions during our initial visit and factor any concerns into our quotation.

Access and Site Constraints

Easy access for deliveries and waste removal keeps costs down. Properties with rear gardens accessed only through the house, narrow side passages, or limited street parking for delivery vehicles all increase labour time and complexity. Victorian and Edwardian terraces near the town centre and seafront often present tighter access than detached properties in Willingdon or Polegate. We assess access during our initial visit and reflect any constraints in our quotation.

Costs by Extension Type

Different extension types suit different properties and budgets. Here is what each typically costs in Eastbourne in 2026.

Rear Extensions

The most common extension type, rear home extensions expand your ground floor into the garden. Small rear extensions under 20 square metres typically cost £32,000 to £48,000. Medium rear extensions of 20-30 square metres run £45,000 to £68,000. Large rear extensions over 30 square metres range from £62,000 to £100,000 or more. Many rear extensions fall within permitted development, avoiding planning application fees and delays, though this depends on your property type and the extension size.

Side Return Extensions

Properties with narrow side passages, common in Eastbourne’s Victorian and Edwardian terraces, can reclaim this wasted space with a side return extension. These relatively small additions, typically 5-10 square metres, cost £18,000 to £38,000 but transform dark, narrow kitchens into bright, usable spaces. Combined with a rear extension, a side return creates impressive open-plan living areas. Properties near the town centre, in Upperton, and along many of the seafront roads often suit this approach.

Wrap-Around Extensions

Combining side and rear extensions into an L-shaped addition, wrap-around extensions maximize the space gained from a single project. These larger undertakings typically cost £52,000 to £98,000 depending on size and specification. Wrap-around designs suit corner plots and properties with good side access, creating substantial new accommodation for open-plan living, large kitchens, or combined kitchen-dining-family rooms.

Double Storey Extensions

Adding accommodation on two levels, double storey extensions typically cost £58,000 to £115,000 for 25-40 square metres of additional floor space across both floors. These projects usually require planning permission and careful design to integrate with your existing roofline. For growing families needing both ground floor living space and additional bedrooms, double storey extensions deliver excellent value per square metre. Many 1930s semis common across Hampden Park, Langney, and Willingdon suit double storey rear extensions particularly well.

Additional Costs to Budget For

The house extension build cost is not your total project cost. Several additional expenses catch homeowners by surprise. Building them into your budget from the start avoids financial stress mid-project.

Professional fees including architectural design, structural engineering, and planning applications typically add £2,500 to £7,500 depending on project complexity. Planning application fees for householder applications currently stand at around £250. Building regulations fees add another £500 to £1,000. Party wall agreements, if your extension affects shared boundaries with neighbours, can cost £700 to £1,500 per neighbour if surveyors become involved.

Kitchen installation, if your extension includes a new kitchen, adds £8,000 to £28,000 or more depending on your chosen specification. Bathroom installation adds £5,000 to £14,000. Flooring, decoration beyond basic, and landscaping to reinstate your garden all add further costs. A realistic total project budget often exceeds the build cost by 20-40 percent once all elements are included.

Getting Accurate Quotes

Online calculators and national averages provide rough guidance but cannot account for your specific property, requirements, and local market conditions. Accurate pricing requires detailed quotations from local builders who have visited your property and understood your project.

We recommend obtaining at least three quotes for any significant extension project. Provide each builder with the same information, ideally architectural drawings if you have them, to ensure quotes are comparable. Ask each builder to specify exactly what is included and excluded from their price.

Be cautious of quotes significantly below others. They may exclude essential elements, rely on inferior materials, or come from builders who will seek additional payments once work begins. Equally, the most expensive quote is not automatically the best. Assess what you receive for your money and check references from previous clients.

A detailed, itemised quote helps you understand where money goes and compare like with like. Vague quotes with single lump-sum figures make comparison difficult and leave room for disputes about what was included.

Is an Extension Worth the Investment?

Beyond the immediate benefit of more space, extensions can add significant value to Eastbourne properties. A well-designed extension that adds a bedroom or creates desirable open-plan living typically adds 60-80 percent of its cost to property value, sometimes more in a strong market.

However, extensions should primarily meet your family’s needs rather than purely chasing property value. The right extension improves your daily life for years, potentially keeping you in a home you love rather than forcing an expensive and disruptive move. In Eastbourne’s property market, where family homes remain in demand, extending often makes more financial sense than moving when stamp duty, legal fees, and moving costs are considered.

Extensions that work best combine practical space improvements with broad market appeal. Open-plan kitchen-diners, additional bathrooms, and extra bedrooms consistently add value. Highly personal additions with niche appeal may not deliver the same return.

Planning Your Eastbourne Extension

Successful extensions start with careful planning. Before approaching builders, consider what you actually need from the additional space. How will you use it? What problems with your current home will it solve? How does it need to connect with your existing rooms?

Research planning requirements for your property. Check whether your extension might fall within permitted development or require full planning permission. Eastbourne Borough Council’s planning portal provides guidance, though professional advice helps navigate complex situations, particularly in conservation areas around Meads and the Old Town.

Set a realistic budget including contingency for unexpected costs. Most experts recommend a 10-15 percent contingency for unforeseen issues. Arrange financing before seeking quotes so you can move quickly when you find the right builder.

Get Your Free Extension Quote

If you are considering extending your Eastbourne home, we would welcome the opportunity to discuss your project. We provide free, no-obligation consultations where we visit your property, understand your requirements, and explain your options. Following our visit, you receive a detailed written quotation with clear pricing and no hidden costs.

Our experience building extensions across Eastbourne means we understand local planning requirements, typical ground conditions, and what works well with the housing stock common to this area. From initial concept through to completion, we manage projects professionally, keeping you informed throughout and delivering results that match our quotations.

Contact us today to arrange your free consultation. Let us help you understand what your Eastbourne extension will cost and how we can bring your plans to life.

Get in touch with a local Eastbourne builder to start planning your home extension.