Westminster · W1 · SW1 · NW1
Kitchen Extensions in Westminster
Central borough with listed and conservation stock — interior and basement work dominates. Bright, open-plan kitchen extensions across London terraces and semis.
Postcodes covered
Quick answer
Builderr delivers side return and rear kitchen extensions across Westminster — W1, W2, W9, NW1, NW8, SW1 and WC2. Typical Westminster kitchen extension cost £90,000–£230,000 over 14–22 weeks including fitted kitchen. The borough sits inside 56 conservation areas with Article 4 directions across most of W1 and SW1, and a substantial share of stock is Grade II or Grade II* listed — LBC is mandatory alongside full planning for any rear-elevation opening, closet-wing demolition or original sash interference. Heritage-led specification per Westminster Design Guide: London stock brick or matching stucco profile, natural Welsh slate roof with hand-made tiles where required, traditional 6:6 Georgian sash matched to existing glazing bar profile, Crittall W20 steel glazing rather than bulk aluminium, lead-clad parapet detail. Mansion-block flats in Pimlico, Maida Vale and St John's Wood typically also require Licence to Alter from freeholder alongside planning + LBC — adds 6–10 weeks to programme. Determination 12–16 weeks combined LBC + full planning.
Westminster Basements SPD restricts rear-extension light wells. CIL Westminster £450/m² Zone 1 (Mayfair / Marylebone / Belgravia), £200/m² Zone 2 (Maida Vale / Pimlico) — significant on net new floor area. Party Wall awards £1,400–£2,200 per neighbour. Building Safety Act 2022 engages for HRB mansion blocks ≥18m or 7 storeys — additional Gateway 2 sign-off required.
Westminster
Kitchen Extensions specialists across Westminster.
We deliver kitchen extensions projects across the full Westminster postcode set — W1, SW1, NW1, NW8. Central borough with listed and conservation stock — interior and basement work dominates.
Every Westminster 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 Westminster 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 Westminster kitchen 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 Westminster
Local planning rules for kitchen extensions in Westminster.
Westminster contains 56 conservation areas covering virtually all residential stock — Mayfair, Belgravia, Bayswater, Marylebone, Pimlico, Soho, St John's Wood, Maida Vale and Fitzrovia among them. Thousands of properties are statutorily listed (Grade I, II* or II). PD rights are removed under Article 4 across most of the borough. The City Plan and individual Conservation Area Audits govern alterations. Basement extensions are heavily regulated under the Basement SPG (single-storey only on most plots, no extensions under gardens beyond 50% footprint). Mansard roof extensions are typically the preferred upward route over rear dormers. Pre-application consultation is essential — Westminster's planning officers operate a structured pre-app service and outright refusals without engagement are common. Listed Building Consent applications run in parallel with planning and require specialist conservation input.
Our planning team handles the full submission for Westminster addresses including drawings, Design and Access Statements where required, and pre-application consultation with the council. We tell you whether your kitchen 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 £21,500–£48,375 on a kitchen extension in Westminster.
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 £107,500.
FAQ
Kitchen Extensions in Westminster.
How much does a kitchen extension cost in Westminster?
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Most kitchen extensions projects in Westminster cost £55,000–£160,000 depending on size, spec and structural complexity. Inner London postcodes typically sit toward the upper end; outer borough projects trend mid-range. All Builderr Westminster quotes are fixed-price with no provisional sums.
Do I need planning permission for a kitchen extension in Westminster?
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Planning rules vary across Westminster. We check permitted development eligibility, conservation area status and any Article 4 directions affecting your specific postcode before quoting. Many kitchen extensions fall under permitted development, but conservation areas and listed buildings need full planning.
How long does a kitchen extension take in Westminster?
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Typical timeline is 10–18 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 kitchen extension references in Westminster?
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Yes — we maintain a live reference list for Westminster and can connect you with two or three completed clients within the borough. We've delivered projects across nearly every Westminster postcode since 2022, so most prospective clients can visit a completed project nearby.
What's included in a Builderr kitchen extension quote in Westminster?
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Every Westminster 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 Westminster
Kitchen Extensions in nearby boroughs
Get a Westminster kitchen extension quote.
Senior consultant call within one business hour. Free desk-based planning assessment for W1, SW1, NW1 and surrounding postcodes. Fixed-scope price — no provisional sums.
