Kitchen Extension Cost in Lewisham: 2026 Price Guide

Few projects change how a Lewisham house feels day to day quite like a rear kitchen extension. Given Edwardian civic buildings around St Mary's church, with the established Victorian and Edwardian terraces of Forest Hill, Sydenham and Hither Green nearby, 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

The single biggest cost variable for a kitchen extension in Lewisham tends to be access rather than the extension itself - narrow terraced streets with no side passage mean materials and spoil go through the house, which shows up in the price. On top of that, the St Mary's and Sydenham Hill and Kirkdale conservation areas often means closer attention to matching brick, roofline and windows, adding cost even where planning permission itself isn't required.

Foundations are the other variable: older Victorian and Edwardian houses near the Horniman Museum and Gardens were often built on shallow footings, so a structural engineer may specify deeper or more extensive foundations than a newer property would 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 Lewisham's conservation areas, permitted development rights can be restricted further, so it's worth checking with the London Borough of Lewisham's planning department - or a builder who works in the area regularly - before you commit to a design.