Islington · N1 · N5 · N7
House Extensions in Islington
Dense Georgian and Victorian stock with heavy conservation — full planning typical. Single and double-storey extensions delivered as a fixed-scope design and build package.
Postcodes covered
Quick answer
Builderr delivers side return and rear extensions across Islington — N1, N5, N7, N19 and EC1. Typical Islington extension cost £65,000–£195,000 over 12–22 weeks. The borough's dense Georgian and Victorian stock requires careful structural design — closet wing infills, side returns and modest rear additions are the typical pattern. The Islington Design and Conservation SPD governs material and detailing requirements.
Islington
House Extensions specialists across Islington.
We deliver house extensions projects across the full Islington postcode set — N1, N5, N7, N19, EC1. Dense Georgian and Victorian stock with heavy conservation — full planning typical.
Every Islington project includes a free desk-based planning assessment before we quote, so you know upfront whether permitted development, prior approval, or full planning applies to your specific address. Our local project manager for Islington has detailed knowledge of the planning department's preferences, the conservation area boundaries, and the common construction details for the prevailing housing stock here.
Quotes for Islington house extensions are fixed-scope after a site survey, valid for 60 days, and never carry provisional sums or open-ended day rates. Every project includes our 10-year structural warranty and 12-month defects period.
Planning in Islington
Local planning rules for house extensions in Islington.
Islington has over 30 designated conservation areas including Barnsbury, Canonbury, Highbury Fields, Thornhill and Upper Street. Article 4 directions cover extensive residential areas, removing PD rights. Planning officers apply strict design guidance via the Islington Design and Conservation SPD. Pre-application advice is recommended for most projects; the council offers a formal pre-app service. Mansard loft conversions are the preferred roof extension type in conservation areas; rear dormers are typically refused.
Our planning team handles the full submission for Islington addresses including drawings, Design and Access Statements where required, and pre-application consultation with the council. We tell you whether your house extension is permitted development, prior approval, or full planning before you sign anything.
Builderr vs other London builders.
The construction industry has a wide distribution of operators. Here's what changes between a directly-employed, fixed-scope outfit and the alternatives.
| Criterion | Builderr | Typical London builder | Cowboy outfit |
|---|---|---|---|
| Labour model | Directly employed team (PAYE) | Mixed subcontract gangs | Day-rate cash labour |
| Pricing | Fixed-scope itemised quote | Estimate + provisional sums | Verbal price + variations |
| Design & engineering | In-house architect + SE | Outsourced, separate billing | Builder draws on the back of an envelope |
| Planning + LDC handled | Yes — included in price | Often charged extra | Builder asks you to apply |
| Party wall surveyors | Instructed by us | Your responsibility | Skipped (illegal) |
| Building control | Plans + site inspections booked by us | Building Notice route | Not registered |
| Project management | Dedicated PM, weekly photo updates | Foreman doubles up | Owner-manager juggles 5 jobs |
| Payment schedule | Stage payments against signed-off milestones | Weekly invoices | Cash up front |
| Insurance | £10M PL + 10yr structural warranty | £2–5M PL only | No documented cover |
| Snags at handover | <3 typical | 20–30 typical | Walk-off mid-job common |
| Variation creep | 0% — fixed scope | +15–25% over original quote | +40%+ regularly |
Save £27,000–£60,750 on a house extension in Islington.
Industry data (FMB, RICS, Which? Trusted Trader 2024) shows the average London construction project overruns by 18–22% on cost and 25–35% on time. Fixed-scope contracts with a single accountable team eliminate that variance. The savings above assume a typical project at £135,000.
FAQ
House Extensions in Islington.
How much does a house extension cost in Islington?
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Most house extensions projects in Islington cost £50,000–£220,000 depending on size, spec and structural complexity. Inner London postcodes typically sit toward the upper end; outer borough projects trend mid-range. All Builderr Islington quotes are fixed-price with no provisional sums.
Do I need planning permission for a house extension in Islington?
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Planning rules vary across Islington. We check permitted development eligibility, conservation area status and any Article 4 directions affecting your specific postcode before quoting. Many house extensions fall under permitted development, but conservation areas and listed buildings need full planning.
How long does a house extension take in Islington?
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Typical timeline is 10–20 weeks on site, plus 4–8 weeks for design, structural engineering and approvals. If full planning is required (conservation areas, mansards, larger extensions), add 8–12 weeks for the planning decision before site start.
Do you have house extension references in Islington?
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Yes — we maintain a live reference list for Islington and can connect you with two or three completed clients within the borough. We've delivered projects across nearly every Islington postcode since 2022, so most prospective clients can visit a completed project nearby.
What's included in a Builderr house extension quote in Islington?
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Every Islington quote covers structural design, party wall notices and surveyor coordination, planning or prior approval submission where required, building control, full build, snagging and a 10-year structural warranty. Kitchen units, sanitaryware and bespoke finishes are itemised separately so you can flex spec without losing fixed-price certainty on the build.
Other services in Islington
Get a Islington house extension quote.
Senior consultant call within one business hour. Free desk-based planning assessment for N1, N5, N7 and surrounding postcodes. Fixed-scope price — no provisional sums.
