Cost guides · 6 min read
How much does a house extension cost in North London?
A house extension is usually the best value way to add space to a home in North London, where moving costs (stamp duty, agents, legals) can swallow tens of thousands before you have gained a single extra room. But "how much does an extension cost" has no single answer, so here is a realistic 2026 guide for Enfield, Cheshunt and the surrounding area.
Typical extension costs per square metre
As a rule of thumb for our area, budget on a per square metre basis for the build, then add kitchens, bathrooms and finishes on top:
| Extension type | Indicative cost per m² (2026) |
|---|---|
| Single storey rear (good quality standard finish) | £2,500 to £2,800 |
| Single storey rear (upgraded finish, lots of glazing) | £2,800 to £3,000 |
| Side return | £2,500 to £3,000 |
| Double storey | £2,500 to £2,900 (better value per m²) |
| Wrap-around | £2,700 to £3,000 |
So a 20 square metre single storey rear extension at our good quality standard finish often lands somewhere around £50,000 to £60,000 for the build, before a new kitchen or bathroom. A luxury specification, meaning bespoke joinery, natural stone or designer fittings, sits outside these bands: we price that individually after a site visit rather than guess at it.
What pushes the price up or down
- Glazing: bi-fold and sliding doors and roof lanterns add cost fast.
- Kitchen and bathroom spec: units, worktops, appliances and sanitaryware vary hugely.
- Groundworks: tricky access, trees, drains or poor ground raise foundation costs.
- Structure: large open spans and steel work add to the frame.
- Finish level: standard, premium or luxury changes the rate significantly.
How to budget properly
Do not rely on a single per square metre figure. The honest way to budget is an itemised estimate that prices each trade, then a fixed quotation after a site visit. Our online estimator gives you an itemised budget for your specific project in about a minute, and every figure is subject to a free site visit before anything is fixed.
Frequently asked questions
Is an extension cheaper than moving?+
Very often, yes. Moving in North London can cost tens of thousands in stamp duty, agent and legal fees before you gain any space, whereas an extension adds usable room and typically adds value.
Does an extension add value?+
A well-designed extension in this area usually adds more value than it costs, especially when it creates an open-plan kitchen diner or an extra bedroom.
What is the cheapest way to extend?+
A simple single storey rear extension with a standard finish is usually the lowest cost per square metre. Double storey extensions give better value per square metre because you get two floors on one set of foundations and roof.