How much does a rear extension cost in Hackney?

A single-storey rear extension on a two-storey mid-terrace house in Hackney typically costs £65,000 to £102,000 all in, including VAT. The building work itself is £52,000 to £86,000; the rest is professional and council fees. Hold back about £8,500 more as a contingency. A high-end finish, a bigger footprint or a new kitchen move the figure up; the table on this page shows the range for each variant and finish.

Do I need planning permission for a rear extension in Hackney?

For a single-storey rear extension on a house outside a conservation area, at the 3.5 m depth priced here, the usual answer is: larger home extension: prior approval needed. Up to 3 m deep on an attached house is permitted development; 3 to 6 m uses the prior approval route; a conservation area or an Article 4 direction can change that. Whether your street is covered by one of those is checked against the planning register in the full report.

How long does a rear extension take in Hackney?

About 23 to 43 weeks from first sketch to sign-off, of which 8 to 16 weeks are on site. Design, drawings and the council's decision take most of the rest. Builders in London are often booked three to six months ahead, which adds to the calendar but not to the cost.

What fees are there on top of the builder's price?

For this job, about £6,500 to £23,000: an architect or designer for the drawings, a structural engineer, building control, any council fee, and party wall surveyors if a neighbour dissents. On top of that, hold back a contingency of about £8,500 for what the ground and the existing house turn up.

Do these figures include VAT?

Yes. Every figure on this page and in the report includes VAT at 20%. Builders often quote without it, so add 20% to any quote marked "plus VAT" before comparing.

House extension cost in Hackney (2026)

A single-storey rear extension on a two-storey mid-terrace house in Hackney typically costs £65,000 to £102,000 all in: the build and the professional and council fees, including VAT, with about £8,500 contingency to hold back on top. The build alone is £52,000 to £86,000, about £3,950 per m² for 17.5 m².

Likely cost, all in

£65,000 to £102,000

Expected about £83,500. With the contingency, have £110,000 available.

Expected £84,000

£65,000£102,000

Mostly Victorian terraces and Georgian townhouses, many split into flats, alongside postwar estates and converted warehouses. Build rates in Hackney run about 5% above our London baseline, for parking, access and labour.

A rear extension adds a room across the back of the house, usually a bigger kitchen and dining space; a double-storey version adds a bedroom above. The price is driven by the footprint, the glazing, the steel needed to open up the existing back wall, and the finish you choose.

Typical all-in totals in Hackney

For a two-storey mid-terrace house of the usual size, before extras such as a new kitchen, bathroom or bifold doors. Including VAT.

Job	Straightforward	Good quality	High end
Single-storey rear extensionabout 17.5 m²	£60,000 to £94,000	£65,000 to £102,000	£77,000 to £120,000
Double-storey rear extensionabout 33 m²	£92,000 to £142,000	£100,000 to £154,000	£118,000 to £182,000
Single-storey side extensionabout 14 m²	£49,000 to £78,000	£54,000 to £84,000	£64,000 to £99,000

Where the money goes: a single-storey rear extension, good-quality finish

The build

Extension: groundworks, structure, roof, glazing, first and second fix£51,500 to £86,000

Fees and permissions

Architect or designer: drawings, planning and building regulations package£4,000 to £11,000
Structural engineer: calculations and beam design£1,000 to £2,500
Council prior approval fee£334
Building control: plan check and inspections£1,000 to £2,000
Party wall surveyors (2 neighbours, if they dissent)£0 to £6,000
Thames Water build-over agreement (if a public sewer is within 3 m)£0 to £1,000

Likely cost, all in£65,000 to £102,000

Contingency to hold back£8,500

Budget to have available£110,500

All figures include VAT at 20%. Builders often quote without VAT, so add 20% to any quote that says 'plus VAT' before comparing it with this report.

Planning permission in Hackney

For this job on a house outside a conservation area: Larger home extension: prior approval needed

? checkRear projection. Assuming the usual 3.5 m depth, the size priced here, it is beyond the standard 3 m but within the 6 m larger home extension allowance. That route needs prior approval from the council, with neighbours consulted, and is not available in a conservation area. At 3 m or less, no prior approval is needed.
? checkHeight. Single storey: no higher than 4 m, and eaves no higher than 3 m if within 2 m of a boundary. A 3 m flat roof at the boundary is the usual answer on a terrace.
? checkHalf the garden. Extensions and outbuildings together may not cover more than half the land around the original house.
? checkMaterials. Materials must be of similar appearance to the existing house, except for a conservatory.

The full report checks the planning register at your postcode for conservation areas, Article 4 directions, flood zones and listed buildings nearby, which change the answer street by street. The decision is London Borough of Hackney's: their website has the local validation list and any supplementary guidance on extensions. Fees are the national statutory figures.

How long it takes

From first sketch to sign-off, about 23 to 43 weeks, of which 8 to 16 on site.

Design and drawings4 to 8 weeks
Prior approval6 to 8 weeks
Structural design, building regulations drawings, tender4 to 8 weeks
Party wall notices4 to 10 weeks
Build8 to 16 weeks
Completion and sign-off1 to 3 weeks

Questions people ask

How much does a rear extension cost in Hackney?: A single-storey rear extension on a two-storey mid-terrace house in Hackney typically costs £65,000 to £102,000 all in, including VAT. The building work itself is £52,000 to £86,000; the rest is professional and council fees. Hold back about £8,500 more as a contingency. A high-end finish, a bigger footprint or a new kitchen move the figure up; the table on this page shows the range for each variant and finish.
Do I need planning permission for a rear extension in Hackney?: For a single-storey rear extension on a house outside a conservation area, at the 3.5 m depth priced here, the usual answer is: larger home extension: prior approval needed. Up to 3 m deep on an attached house is permitted development; 3 to 6 m uses the prior approval route; a conservation area or an Article 4 direction can change that. Whether your street is covered by one of those is checked against the planning register in the full report.
How long does a rear extension take in Hackney?: About 23 to 43 weeks from first sketch to sign-off, of which 8 to 16 weeks are on site. Design, drawings and the council's decision take most of the rest. Builders in London are often booked three to six months ahead, which adds to the calendar but not to the cost.
What fees are there on top of the builder's price?: For this job, about £6,500 to £23,000: an architect or designer for the drawings, a structural engineer, building control, any council fee, and party wall surveyors if a neighbour dissents. On top of that, hold back a contingency of about £8,500 for what the ground and the existing house turn up.
Do these figures include VAT?: Yes. Every figure on this page and in the report includes VAT at 20%. Builders often quote without it, so add 20% to any quote marked "plus VAT" before comparing.

Your own house

Get the figures for your own house

The numbers above are for a typical house. Your report prices your footprint and finish, reads the public records for your address, checks the planning rules for your street, and lists the questions to ask anyone who quotes. You see what we found before you pay.

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Other jobs in Hackney

House extension cost elsewhere in London

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This report is an informed estimate built from public data about your property and current London build costs. It is not a survey, a quote, a valuation or planning advice. Always get written quotes and, where noted, professional advice before committing to work.