House Extensions Hendon
Single storey rear and double storey extensions in Hendon, planning, structure and build under one contract.
- Rated 4.9 from 31 reviews on MyBuilder
- Single-storey rear extension from £40,000
- Free site survey, itemised quote
GS Renovation builds extensions across Hendon, making the most of the plots that come with its interwar semis and suburban houses. We handle groundworks, steel, roofing and the full fit-out as a single managed project.
In Hendon, a single-storey rear extension typically starts from £40,000, or £2,000 to £2,800 per m² (indicative London ranges, Architecture for London, Resi, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Hendon: the structural engineer we appoint designs the structure, we build it, and building control signs it off.
Price guide
| Work | Indicative London range |
|---|---|
| Single-storey rear extension | from £40,000 |
| Rear extension, per m² | £2,000 to £2,800 |
| Side return, per m² | £2,400 to £3,200 |
| Wraparound, per m² | £2,400 to £3,200 |
| Double storey, per m² | £1,800 to £2,600 |
| Basement extension | see the basement page |
Indicative London ranges (Architecture for London, Resi, MyBuilder and Checkatrade, 2026), not a quotation. Prices checked September 2026. Full breakdown: Extension Costs & Planning.
Quick estimate for Hendon
Hendon range: choose above
Rear and side extensions in Hendon
The wide plots common to Hendon's interwar houses lend themselves to substantial rear and wrap-around extensions, and the space down the flank suits a side extension that widens a narrow kitchen into a proper family room. We start with the foundations and groundworks, form the new openings with engineer-designed steel beams, and tie the new roof cleanly into the existing structure.
Many of these projects fall under permitted development, which lets you extend without a full planning application, but some do not. A larger footprint, work to a corner plot, or anything affecting the street scene near Hampstead Garden Suburb can require planning permission from Barnet Council. We assess your specific property first so you know which route applies before any design is finalised.
Housing in Hendon
Take the 16,060 or so homes the valuation list gives Hendon: 62% flats, 38% houses, 20% from before 1919, 37% interwar and 43% post-war. Since most homes here are flats, a flat in Hendon has no householder permitted development rights, so extending one needs planning permission and the freeholder's consent.
Extensions in Hendon's conservation areas and on The Burroughs
Two conservation areas carry Hendon's name, Hendon Church End and Hendon The Burroughs, both designated by Barnet Council on 27 July 1983. Each changes what a house can add without an application. Inside a conservation area a house loses its permitted development rights for a side extension, for a rear extension of more than one storey and for cladding the outside in render, timber or tiles. A side return infill, a wraparound or a two storey rear addition therefore needs planning permission from Barnet. A modest single storey rear extension can still be permitted development, while a flat has no householder permitted development anywhere.
On The Burroughs a further step applies. At 1-8 Burroughs Gardens and the odd numbers 63-77 The Burroughs, Barnet's Article 4 direction takes away the permitted development rights for enlarging the house, so even a single storey rear extension needs an application at those addresses. Build the application period into the programme, and have the structural engineer we appoint develop the foundations and steel once the design has permission, so the drawings are not redone to meet a planning condition.
Double storey extensions on Hendon plots
Adding a storey over a Hendon semi gives an extra bedroom and often an en-suite without losing garden, which suits the family homes typical of NW4. A double-storey extension needs deeper foundations, steel beams sized by a structural engineer, and careful matching of brick and roof line so the addition sits comfortably with the interwar character of the street.
Where the extension meets the shared party wall with your neighbour, the Party Wall Act applies and you serve the correct notices early. Every extension, single or double storey, is built to the Building Regulations and inspected by building control. We work through the planning or permitted development question, the party wall timing, the structure and the internal finishes through to completion.
Kitchen extensions in Hendon
62% of homes in Hendon are flats, and a flat has no householder permitted development, so a ground-floor flat's kitchen extension needs planning permission from Barnet Council and the freeholder's consent. Most kitchen extensions here are on the 38% of homes that are houses. The fit-out is priced on its own page, kitchen renovation in Hendon; the build figures are in the table above.
- Side-return and rear extensions
- Roof works and structural alterations at roof level
- Drainage diversion and build-over agreements with the water authority
VOA Council Tax stock of properties, March 2025, for Hendon Central, Hendon Park, North Hendon & Sunny Hill and West Hendon. Counts rounded by the VOA.
Why Hendon Homeowners Choose GS Renovation
Hendon families choose GS Renovation because we take an extension from groundworks to final decoration with one accountable team. We know how the borough's interwar plots and semis behave, we advise honestly on permitted development versus a Barnet Council application, we coordinate the work around the party wall award, and our founder's 30+ years on the tools means a tidy, well-built result.
- Permitted development checked before you pay for a planning application
- Site left safe and secure at the end of every day
- Weathertight shell reached before the fit-out begins
Built a new extension at rear of property. Laid foundations, drainage, raised floor, new roof and completed all fixtures and interior decoration…
The kitchen has been fitted to the high standard. Saaid was polite, professional, tidy, he pays attention to a little details that make huge…
Saiid did a complete refurbishment of our small bathroom. This involved ripping out the existing bath/shower, basin, toilet, pipework, and tiles and…
FAQ
Frequently Asked Questions about House Extensions Hendon
How much should a Hendon homeowner set aside for house extensions?
A Hendon homeowner should set aside the scoped figure for house extensions, typically within £2,000 to £2,800 per m² for a rear extension (indicative), plus an allowance for the unseen. GS Renovation prices what the NW4 survey shows and names what could change once the structure of a mixed-age home is opened. The cost of permitted development or a planning application to Barnet Council belongs in the same budget.
How deep do foundations go for a Hendon extension?
Deeper than many owners expect, and the engineer sets the depth. Where your Hendon property sits on clay, foundations are taken below the zone where seasonal moisture change moves the ground, and nearby trees push that depth further. New foundations shallower than the existing ones move differently, and cracking appears at the junction. The depth comes from the ground conditions rather than from what is convenient to dig.
Which extension suits a semi detached Hendon house?
A rear extension in most cases, sometimes with a side infill where the plot allows. Semi detached Hendon houses usually have a gap to one boundary and a reasonable garden, so a single storey rear addition adds usable space without dominating the plot. Going out to the side as well changes the roof arrangement and usually the permission route. Both are decided against what the garden can spare.
What happens to the kitchen while a Hendon extension is built?
It is usually out of use for several weeks, and the alternative is planned in advance. Where a Hendon extension takes in the existing kitchen, the units come out once the new structure is weathertight, so the gap between losing the old kitchen and gaining the new one is the disruptive period. A temporary sink and appliances elsewhere in the house make it manageable.
Will a Hendon extension match the existing house?
That is a design decision made at the outset rather than left to the bricklayer. On your Hendon house the options are matching the existing brick or render as closely as the available materials allow, or making a deliberate contrast in a modern material. A poor match reads worse than an honest difference. Where permission is required, the chosen approach usually forms part of what is approved.
Where are materials stored during a Hendon extension?
On site where the plot allows it, which is usually the case here. Most Hendon properties have a driveway or garden space that will take deliveries, so materials arrive in larger loads and are stacked and sheeted rather than ordered piecemeal. Anything that suffers from damp, such as plasterboard and insulation, is kept off the ground and covered from the day it arrives.
Can a single storey rear extension in Hendon Church End go ahead without planning permission?
It can, if it stays within the permitted development limits and the house still has those rights. Hendon Church End Conservation Area was designated on 27 July 1983. Inside it a side extension, a rear extension of more than one storey or external cladding needs permission from Barnet, while a single storey rear extension within the limits does not. A lawful development certificate from Barnet confirms the position in writing before the build starts.
Why does a rear extension at 1-8 Burroughs Gardens in Hendon need planning permission?
Because Barnet's Article 4 direction for those houses, and for 63-77 (odd) The Burroughs, removes the permitted development rights for enlarging a dwellinghouse. The same extension elsewhere in NW4 might need no application. Allow for the decision period, and use that time to settle the structural design, the party wall notices you serve as building owner and the Building Regulations submission, so the build starts once permission arrives.
Does an extension in the Hampstead Garden Suburb Conservation Area need the Trust's consent?
Yes. Building an extension there needs consent from both Barnet Council and the Hampstead Garden Suburb Trust, as two separate processes. The Hampstead Garden Suburb Design Guidance also says rear extensions should generally not be wider than half the width of the rear elevation and, in most instances, less. Check the boundary map before a full-width kitchen extension is drawn, because width is the first thing the guidance limits.
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