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Greater London

Build timeline in London

Realistic week-by-week build timelines for renovations and extensions in London, from first design meeting through snagging and final sign-off.

Local context — London

Council
Varies by borough (32 boroughs + City of London)
Open planning portal →
Cost premium
+18-25% vs UK average (inner London) / +8-15% (outer boroughs)
Typical extension price
A 25 m² rear extension in London typically runs £78,000-£125,000 (standard to luxury, 2026). Side-return extensions in Victorian terraces (Clapham, Islington, Hackney) cluster at £85-110k for a standard spec.
Building Control
Every London borough has its own Building Control; most homeowners use private Approved Inspectors (LABC, BBS, Stroma) for faster turnaround. Inspection lead time is 1-3 working days across most boroughs.
Conservation & Article 4
London has 1,000+ conservation areas. Article 4 directions are extensive across Camden, Hackney, Islington, Kensington & Chelsea and Westminster — assume PD rights are removed in any pre-1940 street until the borough confirms otherwise.
Local quirks that move the price
Parking suspensions (£40-110/day depending on borough) and CPZ dispensations are mandatory on most builds. Party-wall agreements typically needed on both sides for terraces. London Plan policy now requires sustainable urban drainage (SUDS) on most extensions over 5 m² of new hard surface.
High-demand areas in London
ClaphamIslingtonHackneyWandsworthLewishamEaling

Pre-construction (typical 10–16 weeks)

Architect or designer: 3–5 weeks for measured survey and concept drawings. Planning or PD route: 4–8 weeks. Structural engineer: 2–3 weeks. Building Control plans: 2 weeks. Builder tendering and contract: 2–4 weeks. This phase is where most overruns originate — start it before you commit to a builder start date.

On-site construction phases

Single-storey rear extension (25–35 m²): 10–14 weeks. Loft conversion (dormer): 8–12 weeks. Kitchen refit: 4–6 weeks. Full bathroom: 2–3 weeks. Whole-house refurb: 4–7 months. Add 2 weeks for snagging and final account.

Local factors that move the schedule in London

Party-wall agreements (terraced and semi-detached homes in London): allow 6–8 weeks. Material lead times for bi-fold doors and bespoke joinery: 8–12 weeks. Building Control inspections in Greater London: book at least 3 working days ahead. Builder availability for autumn starts is tight — secure dates 4+ months ahead.

What "on time" actually means

Industry data: only ~30% of UK domestic projects finish on the original date. A realistic plan adds 15–20% buffer to the builder's headline duration. Lock dates with a Payment Schedule tied to stages, not weeks — that protects you when the timeline slips.

Get the London build timeline checklist

Free PDF with the full build timeline checklist for London homeowners — straight to your inbox.

FAQs about build timeline in London

How long does a kitchen extension take from first meeting to moving back in?

Realistic end-to-end: 6–9 months. Design and planning: 3–4 months. Build: 3–4 months. Allow 2–3 weeks at the end for snagging, decoration touch-ups and final inspections.

When is the cheapest time of year to start a build in London?

January–March is typically 5–8% cheaper as trades come off the autumn rush. October–December starts are the most expensive due to demand stacking before Christmas.

Can I live in the house during the build?

For rear extensions and loft conversions: usually yes, with dust sheets and a sealed-off zone. For full kitchen or whole-house refurbs: budget 4–8 weeks of alternative accommodation.

More London guides

Planning permission in LondonVetting builders in LondonSave on renovation in London

Build timeline in other UK cities

CroydonEalingEnfieldBromleyBarnetWandsworth

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Disclaimer: This is an industry-informed estimate for guidance only. Build Price IQ (trading under Services R Us Ltd) accepts no liability for any decisions, costs, losses or damages arising from its use. Always verify with a site inspection and written quotes from qualified tradespeople before committing to work.