The 10 extension builders from Google's results for Barnet, 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 GooglePotters Bar
Jmbdesign and Build provides construction and design services for house extensions across Potters Bar, St Albans, and Hertfordshire.
01707 242892 14 The Service Rd, Potters Bar EN6 1JH
on GoogleBarnet
Barnet House Extensions provides house extension building services for properties in Barnet.
07418 355552 117-121 High St, Barnet EN5 5UZ
on GoogleLondon
2pm Architects creates architectural designs for residential extension projects throughout Greater London. Working on rear, side, and wraparound structures, the practice assists householders seeking to enlarge kitchen areas and overall living space.
020 3920 9805 45 Dresden Rd, London N19 3BG
on GoogleLondon
Alstruct Ltd provides house extensions, loft conversions and basement conversions for homeowners in Chiswick and West London. Its services also include groundworks, full property renovations and garden landscaping.
020 8080 8240 15B Raven Rd, London E18 1HB
on GooglePopes Dr, London
LCCL Construction is a design and build company converting lofts, extending houses and renovating homes across East London. It works in areas such as Hackney, Walthamstow, Leyton and Bow, where much of the housing is Victorian terraces, and provides architectural design as part of its service.
020 8037 7332 3rd Floor, Hathaway House, Popes Dr, London N3 1QF
on GoogleBull Hill, Leatherhead
Kt 5 Construction builds house extensions, new properties, conversions, and renovations across Chipping Barnet and North London. The team handles project delivery from initial concept through to final completion while maintaining clear client updates throughout the process.
0845 053 7224 Wesley house, Bull Hill, Leatherhead KT22 7AH
on GoogleLondon
Providing architectural services for domestic extension projects, this practice prepares site surveys, planning submissions, and building regulation approvals. Recent schemes include side extensions, kitchen expansions, and internal alterations for terraced properties in Clapham North.
020 3984 3005 86-90 Paul St, London EC2A 4NE
London
Marken Builders delivers structural extensions and general property renovations in the London Borough of Barnet, focusing on EN4 and EN5 postcodes. Work encompasses complete build services alongside site management for domestic property extensions.
0800 111 4883 15 Nevin Dr, London E4 7LL
Barnet
Barnet Extension Guide 2026 carries out house extension building services in the Barnet area.
In Barnet, single storey, per m² typically costs £2,100 – £2,900. Labour in Greater London runs 16% 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 barnet". They are ranked on Google rating, online presence and other factors.
The figures above are Barnet 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.