Kitchen Extension Cost in Clapham: 2026 Price Guide

Few projects change how a Clapham house feels day to day quite like a rear kitchen extension. Given Georgian and Victorian terraces around Clapham Old Town, with grander 19th-century villas widely spaced towards Clapham Park, it's easy to see why - most homeowners here are after the same outcome, swapping a cramped galley kitchen for a proper kitchen-diner that opens onto the garden.

Typical costs

• Small extension (up to 15m²): roughly £30,000-£45,000
• Medium extension (15-25m²): roughly £45,000-£70,000
• Larger or wraparound extension (25m²+): £70,000 upwards

As with any ballpark figures, these cover the building work and a standard fit-out only - popular add-ons like bifold doors, roof lanterns and underfloor heating will move the total upward, sometimes significantly.

What affects the price locally

In Clapham, the biggest local factor is usually access. Many streets are close terraces with no side access, which means materials have to be carried through the house and skips have to sit on the road - both of which builders will price in. Properties within the Clapham Old Town and Clapham Park conservation areas - Lambeth has 65 in total, among the most of any London borough sometimes face tighter controls on matching brick, roofline and window styles to the existing building, which can add to material costs even for a rear extension that doesn't need planning permission.

Foundations matter too - the Victorian and Edwardian housing near Clapham Common was typically built on shallower footings than current standards expect, so a structural engineer often specifies extra depth that a modern property simply wouldn't need.

Do you need planning permission?

Many single-storey rear extensions fall under permitted development, but there are limits on how far you can extend without full planning permission, and those limits are usually tighter for terraced and semi-detached houses than detached ones. If your home is in one of Clapham's conservation areas, permitted development rights can be restricted further, so it's worth checking with the London Borough of Lambeth's planning department - or a builder who works in the area regularly - before you commit to a design.