Home Extension Design in Ealing: Planning, Costs and What's Realistic in 2026

A home extension in Ealing typically costs £3,200 to £4,500 per m² to build in 2026, at mid-range specification, before VAT and professional fees. Whether you need planning permission depends heavily on the street. Ealing has 30 conservation areas, and six of them carry Article 4 Directions, including the Brentham Garden Estate and the Hanger Hill Garden Estate, where even replacing windows or doors needs an application. This page covers what the council allows, what it costs, and how to check where your home stands.

Studio MASS is a residential design practice led by an architectural technologist. We design and deliver extensions, loft conversions and refurbishments across London, from first feasibility check to completed build.

Do you need planning permission for an extension in Ealing?

Many Ealing extensions do not need planning permission. Outside conservation areas, a single-storey rear extension up to 3 metres beyond the original rear wall (4 metres on a detached house) usually falls under permitted development, as do most loft conversions within volume limits. Inside Ealing's 30 conservation areas the position changes: side extensions, rear extensions beyond 3 metres, and any rear extension of more than one storey need planning permission.

Six conservation areas carry Article 4 Directions that go further: Bedford Park, Brentham Garden Estate, Churchfields (Half Acre Road), Ealing Town Centre (The Grove), Hanger Hill Garden Estate and Hanger Hill (Haymills) Estate. In Brentham and the Hanger Hill Garden Estate the directions cover enlargement or alteration of the house, including replacement windows and doors, porches, hardstandings, front boundary walls and painting previously unpainted surfaces. Brentham's direction dates from 1976; Hanger Hill Garden Estate has a 1976 direction plus a further one in force from 2002. Churchfields' direction is narrower, covering roof alterations only.

Ealing also still uses its SPD 4 Residential Extensions guidance, retained as interim guidance after the old Unitary Development Plan was superseded in 2013. Among its tests: extensions must avoid overbearing appearance, overlooking and unacceptable loss of daylight, and houses must keep a minimum garden, 50m² for smaller houses and 75m² for larger ones. The practical rule: never assume permitted development applies in Ealing until someone has checked your street against the council's conservation area map. That check is part of our Stage Zero review, before any design work starts.

What kinds of homes get extended in Ealing?

Ealing's conservation areas are, in the council's own words, a rich assortment of nineteenth and early twentieth century residential development. Brentham Garden Suburb, near Pitshanger, is an early planned garden suburb protected since 1969 with almost no remaining permitted development rights. The Hanger Hill Garden Estate, built 1928 to 1936, is 361 houses and 258 flats in consistent Tudor half-timbered style. Bedford Park, on the Acton and Chiswick border, is a Victorian garden suburb with 356 listed properties, shared with Hounslow. Hanwell keeps village-scale heritage around its green and clock tower. Between these set pieces, Victorian and Edwardian terraces and semis make up much of the everyday stock.

How much does a home extension cost in Ealing in 2026?

Ealing sits in London's mid-price construction zone. From our 2026 Extension Cost Guide, built from BCIS indices, FMB build cost data and our own completed projects:

A single-storey extension in Ealing costs £3,200 to £4,500 per m² at mid specification in 2026. A loft conversion runs £3,200 to £3,800 per m². Conservation area projects carry roughly 15% on top for material restrictions and period-appropriate detailing, and that uplift is very relevant in Ealing given how much of the borough is designated. These figures are construction only; VAT at 20% and professional fees are additional.

Before a brick is laid, expect £8,000 to £16,000 in professional and statutory fees on a typical project, including the £548 planning application fee that applies from April 2026.

The full breakdown by extension type and specification level is in our free Extension Cost Guide 2026, no email required. For a sense of how we work and what completed projects actually cost, see the Rathcoole Gardens project page and the Drakefield House project page, both London homes taken from first feasibility check to finished build.

Who designs your extension if not an architect?

An architectural technologist designs buildings with a focus on how they are built: construction detail, building regulations, and buildability, alongside layout and light. In the UK "architect" is a legally protected title, so we don't use it. What matters for an Ealing extension is the same either way: design within the local planning context, technical drawings a builder can price accurately, and someone accountable from first idea to finished build. That is what we do, through one team and five stages, starting with a Stage Zero review that tells you what is realistic for your budget and what planning will allow before design begins.

Start with a conversation

The best starting point is our short questionnaire. It takes a few minutes and tells us about your home, your brief and your budget. We review it and arrange a free thirty-minute call, with an honest view on feasibility either way.

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