House Extensions in Northwood
Trusted local builders for homeowners across Northwood and West London. Clear written quotes, honest timelines, and a finished extension you'll be proud of.
- Initial site survey and feasibility assessment (free)
- Permitted Development advice or planning application management
- Structural drawings and engineer's calculations
- Building Regulations application and stage inspections
- Full groundworks and foundations
- Structural steelwork and masonry
- Roof structure, weatherproofing and insulation
- Windows, doors and glazing
- First and second fix electrics and plumbing
- Plastering, screeding and internal finishing
- Building Control completion certificate
Northwood homeowners planning an extension want a builder who understands the area's detached and semi-detached stock — generous plots, mature gardens, and homes that warrant doing things properly.
Lavington Build works with homeowners across Northwood, Ruislip, Eastcote, Pinner, Harrow and Gerrard's Cross. We handle the full process from initial survey and planning advice through to Building Control sign-off, giving you one team and one point of contact throughout.
Northwood (HA6), Ruislip, Eastcote, Pinner, Harrow, Gerrard's Cross, Iver, Denham, Harefield
Fixed written quotes. Labour and materials itemised separately.
One team, start to finish. No coordination headaches between contractors.
Building Regulations handled. Application to completion certificate managed in full.
Surveys before quoting. Northwood's detached and semi-detached properties vary — we visit before quoting.
Fully insured. Public liability cover on every project.
How much does a house extension cost in Northwood?
Between £1,500 and £2,500 per square metre. A single-storey rear extension of around 20 sq m usually costs £30,000–£50,000.
Do I need planning permission for an extension in Northwood?
Most single-storey rear extensions fall under Permitted Development — no permission required. We confirm your position during the free survey.
How long does an extension take?
A single-storey extension takes 10–16 weeks. Double-storey runs 18–24 weeks.
Does an extension add value in Northwood?
Yes — typically 10–20%. Building Control sign-off is essential to realise this at sale.
Get in touch for a free site survey and fixed written quote. We cover Northwood, Ruislip, Eastcote, Pinner, Gerrard's Cross and surrounding West London areas. We reply within 1 working day.