How Much Does a Home Renovation Cost in South West London?

A full home renovation in south west London typically costs between £1,200 and £2,500 per square metre for internal works, with most whole-house projects landing between £120,000 and £350,000. A side return extension usually costs £60,000 to £110,000. A loft conversion commonly costs £55,000 to £100,000.

Those are wide ranges, and they should be. A Victorian terrace off Northcote Road and a 1930s semi in Surbiton present very different problems, and the difference shows up long before anyone chooses a tap.

What follows is a practical guide to what things cost here, what actually adds space, and where the money quietly disappears.

What does a full home renovation cost in south west London in 2026?

Expect £1,200 to £1,800 per square metre for a good cosmetic and services refurbishment, and £1,800 to £2,500 per square metre where layouts change, structure moves or the specification is high. A three-bedroom Victorian terrace of around 110 square metres therefore commonly falls between £130,000 and £275,000.

The single largest variable is not the finish. It is how much of the existing house you are keeping.

Stripping back to brick and joists, rewiring, replumbing, replastering and reconfiguring is a different project from redecorating and replacing a kitchen, even if the finished photographs look similar.

For a national reference point, the UK Houzz & Home Renovation Trends Study put the median renovation spend at £21,440, with the top 10% of renovating homeowners spending £169,000. That is 2025 data, and it is a UK-wide median rather than a London one [1].

South west London sits comfortably above that median. It is one of the most expensive places in the country to employ a trade, and the housing stock is old.

Which renovation adds the most usable space in a Victorian terrace?

The side return adds the most usable ground floor space in a standard Victorian terrace, typically creating a full-width kitchen and dining room. A loft conversion adds the most valuable space by creating an additional bedroom and bathroom. A basement adds the most space overall and costs the most by a considerable margin.

Most south west London terraces were built with a narrow outrigger and a strip of unused ground alongside it. That strip, the side return, is dead space in almost every practical sense.

Filling it converts a cramped galley kitchen into a room the whole household actually uses. It is the single most transformative thing you can do to a Victorian terrace, and it is why the same project appears on so many streets in Balham, Tooting and Putney.

How much does a side return extension cost?

A side return extension in south west London typically costs £60,000 to £110,000, depending on width, glazing specification and whether the rear wall is opened up at the same time. Structural glazing, roof lanterns and sliding doors account for a significant share of that range.

The build itself is relatively modest in square metre terms. What drives the cost is everything that comes with it: steelwork to support the existing structure, new foundations tight against a neighbouring boundary, drainage diversions and the glazing that makes the room worth having.

Three costs are routinely missing from early budgets:

Party wall agreements at roughly £700 to £1,500 per neighbour, and a terrace has two.

Structural engineer fees at £800 to £2,000 where beams are involved, which on a side return they always are.

Drainage alterations where a shared Victorian sewer runs beneath the extension footprint, which can require a build over agreement with Thames Water.

How much does a loft conversion cost?

A loft conversion in south west London typically costs £55,000 to £100,000. A rear dormer conversion with a bedroom and en suite sits in the middle of that range. A hip to gable conversion on a semi-detached property, or an L-shaped dormer on a terrace, sits towards the upper end.

Lofts are usually the better financial decision of the two, because they add a bedroom, and bedroom count is the first filter every buyer and tenant applies.

The constraint is head height. You need roughly 2.2 metres from the existing ceiling joists to the ridge for a conversion to work without lowering ceilings below, which is an expensive and disruptive alternative. Many Victorian terraces have it. Plenty of 1930s semis do not.

Do you need planning permission in a conservation area?

Many side returns and rear dormers fall under permitted development, but permitted development rights are restricted in conservation areas and removed entirely on listed buildings. South west London has a high concentration of conservation areas, so this needs checking before any design work begins.

Wimbledon Village, Barnes, parts of Putney, Richmond and Kew, and a good deal of Clapham and Wandsworth Common sit within designated conservation areas. Article 4 Directions apply in places, removing rights that would otherwise be automatic.

Rear dormers in particular are frequently refused in conservation areas where they would be visible from the street. Front-facing rooflights are often required to be conservation-style and flush-fitting.

The practical step is a pre-application enquiry to your borough before you commission drawings. It costs a fraction of an architect’s fee, and a great deal less than a refused application and a redesign.

Building regulations approval is needed whether or not planning permission is. Budget £500 to £1,200.

Is renovating still worth it now south west London prices have softened?

Softening prices strengthen the case for renovating rather than moving, because transaction costs remain fixed while the gain from trading up has narrowed. They also raise the risk of over-improving, so the local ceiling price matters more than it did.

According to ONS data for May 2026, the average house price in Wandsworth was £660,000, a 6.1% fall on the year. In Richmond upon Thames the average was £789,000, down 2.5% [2] [3].

The property type figures tell the more useful story.

Source: ONS, May 2026 provisional [2] [3]

In Wandsworth, the step from a terraced house to a semi-detached one is £335,000. The step from semi-detached to detached is a further £1,021,000 [2].

Set a £90,000 side return against a £335,000 ladder gap and the arithmetic makes itself. Add the cost of the move on top, in stamp duty, agent fees and legals, and the case rarely goes the other way.

The caution is the ceiling. Every street has a figure buyers will not exceed, and in a falling market that figure is moving down rather than up. Check what the largest comparable house on your road has actually sold for in the past two years before you set a budget.

How long does a home renovation take?

A side return extension typically takes twelve to eighteen weeks on site. A loft conversion usually takes eight to twelve weeks. A whole-house renovation commonly takes six to nine months. Design, planning and tender add a further three to six months before anything begins.

The design and consent phase is the one people underestimate. A planning application alone takes eight weeks from validation, and validation is not instant.

Bespoke joinery is often quoted at eight to fourteen weeks from sign-off, and stone worktops cannot be templated until units are physically installed, which adds a fortnight in the middle of the programme.

If you want to be in for Christmas, the drawings need to be finished by roughly February.

How do you choose the right builder?

Get three quotes priced against the same drawings and the same written specification, check the contractor has completed comparable projects nearby, confirm insurance and warranty cover in writing, and understand exactly how and when money is released.

That last point is where most renovation stories go wrong. Payment schedules that run ahead of progress are the single most common source of dispute.

“The thing that determines how a renovation feels is almost never the design, it’s the structure around the money and the decisions,” says Sam Heague, Head of Brand at Beams Renovation, which works with homeowners across London.

“If the price is fixed before you start, and payments are only released once you’ve actually seen and approved the stage they relate to, most of the anxiety disappears. What we see going wrong is people agreeing a schedule of payments by date rather than by completed work, then discovering three months in that they’ve paid for more than they’ve got.”

Ask any contractor how many trade days they have allowed and what happens to the price if something unexpected appears behind the wall. The answers separate those who have planned the job from those who have priced it optimistically.

What should you set aside for the things that go wrong?

Hold 15% of the build cost as contingency on a modern property and 20% on anything built before 1930. South west London’s Victorian and Edwardian housing stock reliably produces surprises once floors come up and plaster comes off.

The usual suspects are perished lath and plaster, undersized or perished joists, Victorian drainage in poor condition, historic damp behind cupboards, and wiring that has been extended rather than replaced across several decades.

None of these is a disaster. All of them cost money, and all of them are cheaper to deal with while the house is already open than to revisit later.

Do not spend the contingency on upgrades in month one. It exists for the house, not the kitchen island.

Frequently asked questions

Is VAT charged on a home renovation?

VAT at 20% applies to most domestic renovation work. A reduced rate can apply to properties empty for two years or more, and to certain conversions. Always confirm in writing whether a quoted figure includes VAT, as the difference on a £200,000 project is £40,000.

Can you live in the house during a renovation?

You can during a loft conversion or a contained extension, though it is noisy and dusty. A whole-house renovation involving a rewire and replumb realistically requires moving out, and that rental cost belongs in the budget from the start.

Do you need an architect?

For a straightforward loft or side return, an experienced architectural designer or a design-and-build contractor is usually sufficient. For structural changes, conservation area applications or anything unusual, an architect earns their fee at the planning stage.

How much value does a renovation add?

A loft conversion adding a bedroom and bathroom tends to perform best, because it changes the property’s search bracket. A side return improves saleability considerably but adds value less predictably. Neither is guaranteed to return its cost in a softening market.

References

[1] Houzz, UK Houzz & Home Renovation Trends Study, published 27 May 2025. Cited for the median UK renovation spend of £21,440 and the top 10% spend of £169,000. Note this is 2025 data. houzz.co.uk

[2] Office for National Statistics, Housing prices in Wandsworth, May 2026 provisional data. Cited for the Wandsworth average of £660,000, the 6.1% annual fall, and the property type breakdown. ons.gov.uk

[3] Office for National Statistics, Housing prices in Richmond upon Thames, May 2026 provisional data. Cited for the Richmond average of £789,000, the 2.5% annual fall, and the property type breakdown. ons.gov.uk

Cost figures in this article are typical ranges for south west London and should be treated as indicative. Actual prices vary by property, condition, planning constraints, specification and contractor. Always obtain written quotes and check your planning position with your local authority before committing to a project.