How Much Do House Extensions in Wimbledon Cost?

House extension expenses vary considerably across the United Kingdom, influenced by the project’s scope, the structural complexity you select, and the materials involved. Industry data frequently places a single-storey rear extension starting at around £1,500 per square metre for a basic approach, while many standard builds settle in the £1,800–£2,500 per square metre bracket. If you plan sophisticated steel frames, intricate glazing, or high-end decorative finishes, total costs can climb above £3,000 per square metre.

In Wimbledon, part of the London Borough of Merton in southwest London, labour costs usually range from moderate to high, reflecting the area’s desirability, good transport links, and strong property values. If you own an Edwardian terrace near Wimbledon town centre or a 1930s semidetached in Colliers Wood, you might face added structural tasks—like reinforcing foundations or handling damp—that can lift your ultimate bill. Larger expansions commonly reside in the £40,000–£100,000+ zone, while smaller single-storey or side-return builds can be cheaper. Big multi-level or high-spec expansions exceed average baselines if advanced engineering or bespoke decor are essential. Adding or moving a kitchen or bathroom adds costs for plumbing, electrics, and waterproofing.

When collecting contractor quotations, ensure each clarifies foundation excavation, structural tasks, roofing, fittings, finishing, labour overheads, and so forth. Also confirm if VAT—commonly 20%—is factored in. While home-improvement sources and renovation websites can suggest approximate sums, genuine accuracy arises from gathering multiple quotes from reputable local builders and comparing them line by line.

Different Types Of Extensions

There are also different requirements for different extensions. Under is a list of the different types of house extensions:

Side extensions
Single storey extensions
Extensions more than one storey

They each have their own specific limits concerning such as rear extensions requirements, height, roofing and windows. For extensions of more than one storey, there is for example a requirement that roof pitch must match the existing house as far as practicable.

Wimbledon

Wimbledon is famously known for its tennis championships and its blend of upscale residential streets, historical architecture, and convenient commuter links. Areas like Wimbledon Village feature elegant period homes, while the broader district contains Edwardian terraces, 1930s semis, and modern flats. Single-storey rear expansions often unify smaller kitchens or living rooms, offering open-plan spaces. Side-return extensions are common in older terraced roads near Wimbledon station or South Wimbledon, capturing leftover land next to a house. Loft conversions remain popular for pitched-roof homes around Raynes Park or Colliers Wood, adding new bedrooms or offices. Basements, though not as frequent, appear in certain high-end roads near Wimbledon Common.

Local contractors note that Wimbledon roads—particularly near the bustling town centre or around peak commuter times at Wimbledon station—can be congested, so scheduling skip deliveries midmorning is recommended. Labour costs often rank above average, especially near Wimbledon Village or prime parts of Raynes Park, reflecting the area’s affluence. A well-executed extension can significantly raise day-to-day convenience and property value, particularly if you live close to strong transport lines (like the District line or mainline trains) or near green spaces such as Wimbledon Common. Consulting neighbours in Victorian or Edwardian terraces early helps avoid boundary tensions or party-wall issues.

Whether you’re envisioning a single-storey solution to refresh a 1930s semidetached near Colliers Wood or a multi-level plan for an Edwardian terrace up by Wimbledon Village, moulding your design to Wimbledon’s suburban and historical character paves the way for a smoother planning journey.

Getting Started

Before launching the physical build, identify which extension design suits your Wimbledon property best. A single-storey rear arrangement merges older ground-floor rooms into a bright open-plan zone, while a double storey version increases both ground and upper-floor living space, perhaps creating a new bedroom or upstairs bathroom. A side extension can reclaim a driveway or alleyway, while a loft or basement might be relevant if outward expansions aren’t possible—though basements are typically rarer across Wimbledon, except in some premium roads, whereas loft conversions remain a go-to for pitched-roof houses near Raynes Park or Merton Park.

A thorough plan from the start saves hassle mid-project. Formulate a detailed budget referencing typical local labour fees, average material costs, plus a contingency for structural complexities or premium finishes. If your layout includes notable structural changes—like demolishing key bearing walls—then an architect or professional building designer is beneficial. Some contractors do design-and-build, but often require partial sketches or partial planning consents to quote accurately. Many Wimbledon homeowners first consult an architect, then approach recommended contractors for estimates.

Selecting a contractor well in advance is smart, as good local teams can be fully booked—particularly in times of local building surges near Wimbledon Common or during the tennis tournament months. Gathering multiple quotes early allows you to compare cost breakdowns carefully, verify references, and pick a builder suiting your style. A knowledgeable contractor might refine your plan—for example, adding skylights to optimise daylight in a new open-plan kitchen or introducing a discreet utility closet behind a lounge area.

Project Management

Extensions typically rely on one of two management strategies:

1. Single contract (design-and-build or main contractor)
   Here, you sign one contract with a building firm responsible for everything—foundation works, structural frames, plumbing, electrics, roofing, finishing. They subcontract trades, charging around a 10–15% coordination fee. This consolidates scheduling and gives you a singular contact point.
2. Multi-trade or split contract
   You personally employ groundworkers, carpenters, roofers, electricians, plumbers, and so on. Though you might drop the main contractor’s overhead, you must harmonise each trade’s schedule. If one trade runs late, subsequent steps stall, risking extra costs. This approach suits homeowners able to devote daily or weekly oversight.

For bigger expansions in Wimbledon, single-contractor arrangements are common, particularly for families who lack time to direct all trades. If you do multi-trade, confirm you can frequently monitor progress, schedule deliveries, and handle potential delays.

Do I Need Planning Permission?

Whether you need planning permission is determined by the project’s size, height, and how it relates to property boundaries. Under Permitted Development Rights, you can sometimes expand without a formal planning application if you stick within certain dimensional guidelines. If you exceed those, you must file a householder planning permission application.

Under are the general rules that apply to all extensions:
Only half the area of land around the "original house" can be covered by extensions or other buildings.
Extensions cannot be higher than the highest part of the existing roof; or higher at the eaves than the existing eaves.
Where the extension comes within two metres of the boundary the height at the eaves cannot exceed three metres.
Extension cannot be built forward of the ‘principal elevation’ or, where it fronts a highway, the ‘side elevation’.
The work cannot include:
verandas, balconies or raised platforms.
a microwave antenna (e.g. TV aerial or satellite dish).
a chimney, flue or soil and vent pipe.
any alteration to the roof of the existing house.
On Article 2(3) designated land the work cannot include cladding of the exterior.
The materials used in any exterior work must be of a similar appearance to those on the exterior of the existing house.
Source: Planning Portal.

Sections of Wimbledon close to the Village or near conservation zones around Wimbledon Common might restrict typical PD freedoms further. Checking with Merton Council’s planning resources or a local planning specialist clarifies if you’re PD-eligible or must apply for official permission.

A New Storey?

Loft conversions that reshape roofs or insert dormers ordinarily require planning permission. However, if you meet certain requirements and file prior approval, you might add a new storey under permitted development. Otherwise, Householder/Full Planning Permission is typical. If your home complies with these guidelines, read the bullet points below:

Number of additional storeys:
One storey can be added to a single storey house
Two storeys can be added if the house has more than one storey.

Height increases:
The house cannot exceed 18 metres in total height
Each added storey cannot add more than 3.5 metres to the total height
If not detached (e.g. terrace or semi) the total height cannot be more than 3.5 metres higher than the next highest building that the house is attached to, adjoins, or is in the same row as.
The additional storeys must be constructed on the principal part of the house*
The additional storeys must not exceed 3 metres in height or the height of any existing storey in the principal part of the house (measured internally from floor to ceiling)
Engineering operations must only include works within the existing curtilage of the house to strengthen existing walls and foundations
The materials used must be of a similar appearance to those used in the construction of the exterior of the current house
Windows must not be placed in any wall or roof slope forming a side elevation of the house.

Extra rules might apply upon completion. In many older Wimbledon terraces or semidetached roads, preserving local roof shape or facade lines can be key, so consult planners carefully if you want an extra storey.

A New Basement?

Building a basement usually requires planning permission, and sub-ground excavation under your property similarly often triggers permission given the project’s extent. It’s advisable to talk to Merton Council’s planning office early, since some roads near Wimbledon Common or historical enclaves around the Village can carry conservation constraints. Basements can be among the priciest expansions, so even if no direct planning approval is activated in certain scenarios, Building Regulations remain mandatory for structural strength, damp, ventilation, and safe exits.

Review any local rules overriding PD expansions. Some prime roads near Wimbledon Common or the Village might limit or heavily scrutinise basement digs for fear of harming adjacent properties or changing the local environment.

Remember Building Regulations Application

Regardless of the size and shape of your extension, it must meet building regulations requirements. This is also regardless of whether you need planning permission or not.

You will need to file a building regulations application. Smaller or simpler expansions might use a Building notice, whereas bigger ones typically require a Full Plans Application, where you submit detailed plans in advance. With a Building Notice, inspectors check the work on site.

Keep in mind that certain installations—like electrics, windows, plumbing, or heating systems—can be carried out by tradespeople who are registered under competent person schemes (for instance, NICEIC for electrical installations or FENSA for window replacements). By using these schemes, qualified professionals self-certify compliance without separate building control visits for those parts of the build.

A Full Plans Application often highlights design or safety issues early, while a Building Notice might suffice for simpler expansions. Ultimately, building control must confirm your completed extension meets code regulations, ensuring safety and reliability.

What’s The Difference Between Planning Permission And Building Regulations Application?

Whereas planning permission checks whether the extensions meets local and national planning policies, building control is about structural and regulatory compliance.

Even if your Wimbledon extension is given the green light under PD or obtains planning consent, building regulations remain essential—for instance, ensuring robust foundations, safe wiring, or adequate insulation. In older Edwardian or Victorian homes around Wimbledon Park or Merton Park, verifying your new loads don’t destabilise existing walls is vital.

DIY Contribution

Homeowners sometimes aim to undertake parts of the extension themselves. Painting, decorating, or landscaping can be productive DIY tasks if you have the skills. Doing your own demolition, in a limited sense, might also be feasible—if you identify which walls are structurally bearing and follow safety measures.

But bigger tasks—like electrical wiring, gas piping, or major structural modifications—generally require accredited pros. Mistakes could be dangerous or lead to big remediation costs. Assess your capabilities honestly; overreaching might derail the schedule. Builders might pause if your DIY tasks lag, raising final bills. If partial DIY suits you, consulting a professional in the early stage can curb major errors.

In Wimbledon, partial DIY often revolves around finishing touches—like painting interior walls or reshaping gardens—after the main structural phase concludes. Doing advanced mechanical or structural tasks solo can compromise official checks or degrade overall build quality.

Do I Need An Architect?

If your extension is fairly straightforward, you may get by with a structural engineer or building designer. However, for a more substantial or intricate layout, an architect typically contributes key benefits. Skilled architects balance functionality, daylight, and aesthetic coherence so that the new and old areas complement one another.

They can also establish whether your plan is likely within PD or if planning permission is needed. Although using an architect raises up-front costs, it commonly prevents mid-project design errors or structural conflicts that inflate budgets unexpectedly.

Wimbledon includes varied property styles—elegant period houses near the Village, 1930s semis around Merton Park, modern flats near South Wimbledon. An architect might propose partial glass ceilings, folding walls for open-plan living, or subtle facade changes while preserving the area’s suburban charm.

How Long Does It Take To Build An Extension?

Formulating a realistic timetable is vital. A smaller single-storey rear extension—assuming standard materials, a simple layout, and PD compliance—could wrap up in a few weeks once ground and structural tasks begin. Larger expansions, multi-floor or multi-room, might stretch from a few months to half a year or more, influenced by structural complexity and how many trades are involved.

Sometimes, short-term relocation is needed if you remove key walls or disconnect essential utilities. Even if you stay, expect dust, noise, and partially unavailable rooms for a while.

Plan for setbacks. Unfavourable weather could halt external construction, inspectors might request small design revisions, or deliveries might be late. Coordinating a sensible timeline with your contractor trims stress, and finishing earlier than predicted is always a bonus. A contingency in your budget is likewise advised if hidden structural demands or finishing alterations crop up.

Wimbledon roads near the main station, the Village, or major thoroughfares like the A219 can experience congestion, so skip deliveries often avoid early morning or late afternoon. Modifying finishes or structural details once the build starts can also postpone your final wrap-up date.

House Extensions Step By Step

Though planning an extension can be extensive, with good foresight, trustworthy pros, and a guided budget, you can succeed. Whether you aim for a more spacious kitchen-diner, new upstairs rooms, or a basement, keep tabs on each phase and watch for common stumbling blocks.

1. Start by confirming what you want to achieve—more natural light, a larger social area, or additional bedrooms.
2. Then decide how best to organise the project.
3. Check if you need planning permission and what kind of building regulations application you need to send in.
4. Gather quotes from at least three builders if possible, ensuring each has a solid track record and good references.
5. Check that their quotes are like-for-like in terms of scope.
6. Factor in the cost of planning applications, building control fees, and professional services such as architectural drawings or structural engineering.
7. Then develop a realistic schedule, communicate frequently with your chosen contractor, and keep a close eye on both time and budget.
8. Finally, as the build nears completion, consider a thorough inspection—often called a snagging survey—conducted alongside your main contractor or an independent professional. Resolve any finishing flaws before signing off and making final payment. Keep building control certificates, warranties, and other relevant records for prospective property sales or remortgaging.

When your Wimbledon extension completes and passes all checks, you’ll enjoy a larger, more usable living environment. Whether you built an open-plan ground floor or an extra bedroom upstairs, the change often heightens comfort and raises property appeal—especially near transport nodes like Wimbledon station or scenic spots like Wimbledon Common. A snagging survey identifies small cracks, uneven paint lines, or other finishing defects so your builder can fix them. Filing building control approvals and warranties proves your compliance with regulations, reassuring potential buyers or lenders should you move or refinance. Ultimately, your newly enlarged Wimbledon home can fit your family’s changing needs for many years.