The London extension playbook.
Nine in-depth, London-only guides on cost, planning, design, structure and contracts — written the way we'd brief a first-time client sitting across a kitchen table in Hackney or Ealing. Real numbers, real boroughs, no filler.
- 9
- in-depth guides
- 33
- boroughs covered
- 2026
- cost data
- 100%
- London-specific
Start here
The four deep-dives that answer the questions London homeowners ask us most.
KitchensThe London kitchen extension guide
Costs, the four layouts that work in a 4.6 m terrace, glazing strategy and a full worked budget.
StrategyLoft conversion vs extension: which first?
Cost per square metre, value uplift by property type, planning risk and disruption — head to head.
Two storeyDouble-storey extensions in London
The 3 m rule, the 45-degree daylight test, foundation and steel strategy, and a £233k worked example.
ContractsHiring a London builder without getting burned
KYB checks, reading a priced schedule, JCT contracts, stage payments, retention and variation control.
Cost, planning & delivery
How much does a house extension cost in London (2026)?
Per-sqm ranges by borough tier, extension type and finish level. Where the money actually goes, and what pushes London costs above the national average.
Planning permission for London extensions
Permitted development vs full planning, Article 4 boroughs, conservation areas, prior approval, and when a Lawful Development Certificate is the smart route.
The Party Wall etc. Act 1996 — a London homeowner's guide
Which notices to serve, timelines, dissent handling, surveyor fees, and how to keep neighbour relations intact through the build.
Side return extensions in London Victorian terraces
Why the alley works, structural strategies (steel, portal frame, box), glazing options, and typical delivered costs.
A realistic 6–12 month London extension timeline
Every stage from architect brief to snag list, with the London-specific delays that most homeowners don't budget for.