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

A home extension in Hackney typically costs £4,000 to £5,500+ per m² to build in 2026, at mid-range specification, before VAT and professional fees. Planning-wise, Hackney is a borough of two halves: long Victorian streets where ordinary permitted development still applies, and conservation areas where it does not, several of which gained new Article 4 Directions as recently as May 2025. Knowing which half your street sits in is the first question. This page covers what the council allows and what it costs.

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 Hackney?

Many Hackney 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, and that covers plenty of the borough's Victorian terraces in Clapton, Homerton and around London Fields. Inside a conservation area, side extensions and rear extensions beyond 3 metres, and any rear extension of more than one storey, need planning permission.

Bear in mind that a large share of Hackney's period houses are converted into flats, and flats have no householder permitted development rights, so external alterations to a flat need planning permission anywhere in the borough.

Which Hackney conservation areas have Article 4 Directions?

Hackney has made Article 4 Directions over several conservation areas that remove householder permitted development rights, and the list has grown recently. Directions over the Brownswood and Well Street conservation areas took effect on 9 May 2025, and over Beck Road on 28 May 2025. A Direction covering part of Shacklewell Green has applied since 22 October 2019, and the De Beauvoir and St Mark's conservation areas have longer-standing Directions covering works to houses.

In these areas the Directions remove rights under the curtilage-of-a-dwellinghouse and minor operations classes, which is why even window and front door changes can need planning permission in Brownswood, Beck Road or Well Street. If you own a house in De Beauvoir or Stoke Newington's conservation streets, assume a planning application and design for it from the start.

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

Hackney sits in London's inner price band. From our 2026 Extension Cost Guide, built from BCIS indices, FMB build cost data and our own completed projects:

A single-storey extension in Hackney costs £4,000 to £5,500+ per m² at mid specification in 2026. A loft conversion runs £3,200 to £3,800 per m², with inner-London projects tending toward the top of that range. Conservation area projects carry roughly 15% on top for material restrictions and period-appropriate detailing. 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 is in our free Extension Cost Guide 2026, no email required. For a sense of how we work and what finished projects cost, see the Rathcoole Gardens project page and the Drakefield House project page, both completed London projects with real budgets.

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 a Hackney 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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