The 10 extension builders from Google's results for Harrow, ranked on Google rating, online presence and other factors. Updated 10 September 2026.
on GoogleLondon
Architectural design and planning applications for home extensions are handled by Divi Design in Romford and Greater London. The firm creates extension plans and manages projects to enlarge and reconfigure residential living spaces.
020 3488 2828 Divi-Design, 124 City Rd, London EC1V 2NX
on GoogleLondon
Detailed Planning assists property owners in Enfield with residential house extensions, including rear, side and roof additions. The firm offers design and planning support aligned with local council guidelines and property character.
020 8150 0494 Detailed Planning Ltd, Greenside House, 50 Station Rd, London N22 7DE
on GoogleLondon
AGA Associates provides architectural planning and project management for home extensions and residential refurbishments across Wandsworth. The practice works on Victorian and Edwardian terraced houses, detached villas, and modern infill developments, overseeing projects from initial consultation to completion.
020 8014 8130 13 Hanover Square, London W1S 1HN
on GoogleHarrow
Simply Extend builds house and kitchen extensions across East and South London, covering areas such as Croydon, Lambeth and Wandsworth. The business manages residential builds through assigned project managers, handling groundworks, brickwork construction, plastering and internal fittings.
Harrow
Property extensions, loft conversions, and home refurbishments are delivered across Harrow by Tcm Building Maintenance. The company coordinates structural alterations and urgent repairs, including work within the Harrow on the Hill conservation area. Projects are managed directly from initial assessment to site completion.
Harrow
Plus Rooms provides house and kitchen extension services to homeowners in Richmond-upon-Thames and across South West London. The company manages projects from design through to construction, handling planning regulatory requirements along the way. Its team also builds loft conversions.
Harrow
Ionesi Development constructs extensions, loft conversions, and new builds across Harrow and West London. Its team handles property renovations alongside tiling, painting, decorating, bathroom fitting, and landscaping services.
07417 573749 154 Courtenay Ave, Harrow HA3 6LW
Harrow
Taskino assists homeowners in Harrow by arranging house extension projects, including expanded kitchen layouts and additional reception rooms. The platform connects clients with builders to carry out structural expansions and property reconfigurations.
Harrow
Home Extensions Rus manages design, planning applications and building work for house extensions in Harrow, Pinner, Stanmore and Edgware. The firm specialises in expanding 1930s to 1970s residential properties to accommodate growing households.
London
Serving Kentish Town and North West London, Working Builders undertakes complete bathroom refurbishments alongside broader home improvement projects. The business carries out house extensions, loft conversions, property renovations, and garden wall construction across the NW5 area.
020 8688 5570 16 Pandian Way, London NW1 9AE
In Harrow, single storey, per m² typically costs £2,100 – £2,900. Labour in Greater London runs 15% above the UK median, which accounts for most of the difference from the same job elsewhere.
These are the firms from Google's results for "house extensions harrow". They are ranked on Google rating, online presence and other factors.
The figures above are Harrow ranges. These explain what drives them, so you can read a quote properly.
Per-square-metre prices for single-storey, two-storey, side return and kitchen extensions, costs by size, the fees outside the build price, and planning limits by nation.
The permitted development limits for extensions, lofts, porches and outbuildings in England, where the rights do not apply, what prior approval and a certificate cost, and how Wales, Scotland and NI differ.
When the Party Wall Act applies, which notice to serve and how far ahead, what your neighbour can do, what a surveyor's award costs, and the rules in Scotland and NI.
Under permitted development, three metres for a terrace or semi and four for a detached, doubled to six and eight under the prior approval process. Height, materials and how much garden you cover all carry separate limits, and none of it applies in a conservation area.
If you are excavating within three metres of a neighbour's foundations or building on the boundary, yes. You must serve notice two months before work starts. Skipping it is the most common reason extension projects stall.