Islington · N1 · N5 · N7 · EC1
Rear extensions, side returns and open-plan kitchen extensions for Islington's Victorian and Georgian terraces. We handle Islington Council planning — including conservation areas and Article 4 — party wall notices and Building Regulations from first survey to final snag.
Islington is one of London's most tightly controlled planning environments. A large share of the borough's Victorian and Georgian terraces sit within conservation areas covered by Article 4 directions — which means the Permitted Development rights homeowners rely on elsewhere simply do not apply. In N1, N5, N7 and EC1 you should assume a full planning application will be needed for any rear extension.
That is not a reason to abandon the project — it is a reason to work with people who know what Islington's planning team approves: well-proportioned rear and side return extensions, sympathetic materials, and designs that respect neighbouring amenity. We will tell you plainly what is achievable on your plot before you spend a penny on drawings.
Indicative London build-cost ranges. Every project is different — a free site survey gives you an accurate, itemised figure.
Want a personalised range first? Try our free Extension Cost Calculator.
We assess your plot, check whether you are in a conservation area or Article 4 zone, and confirm what Islington Council is likely to approve.
Drawings, structural calculations and a full planning application to Islington Council — or a Certificate of Lawfulness where Permitted Development still applies.
Party Wall Notices served on adjoining neighbours at least two months before work starts. Building Control applications and inspections handled throughout.
A single-storey rear extension typically takes 10–16 weeks on site under a written JCT contract with staged payments. We finish with a full snagging walkthrough.
Leave your details and we will send you honest advice on what your house allows and what it should cost. No obligation, no pressure.
Ready to talk now? Get a free quote →
Almost certainly, yes. A large proportion of Islington's housing stock sits within conservation areas subject to Article 4 directions that remove Permitted Development rights. If you own a property in N1, N5, N7 or EC1, assume from the outset that full planning permission will be needed and plan your programme accordingly. We confirm your property's status at the free survey.
Typical London build costs in 2026 are £2,000–£2,600 per square metre at standard specification, £2,600–£3,400 mid-range and £3,400–£4,500+ at high specification. A 16sqm (4m × 4m) rear extension at standard spec typically falls in the £32,000–£42,000 range for build only, before professional fees and VAT considerations.
The build itself typically takes 10–16 weeks on site. The total programme — architect, full planning application to Islington Council, party wall and Building Regulations — is typically 9–14 months for a terrace requiring full planning permission.
Islington's planning team scrutinises rear extensions closely, especially in conservation areas: proportion, materials and impact on neighbouring amenity all matter. Well-designed single-storey rear extensions with sympathetic materials are regularly approved; oversized or unsympathetic schemes are not. Good drawings from a designer who knows the borough make the difference.
If you are building on or near the boundary of a terraced or semi-detached property, yes — Party Wall Notices must be served on adjoining neighbours at least two months before work starts. We manage this as part of the project.
Want the deep dive? Read our full Islington rear extension guide, the single-storey extension ideas guide and the conservation area guide.
Free survey, straight advice, no pressure. If an extension is not right for your house, we will tell you.
Get a Free Quote