House Extensions Southgate
Single storey rear and double storey extensions in Southgate, 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 extends Southgate's interwar semis and detached houses, the kind of 1930s homes in N14 that sit on generous plots with room to grow. Whether you want a rear kitchen extension, a side infill or a double storey addition, we handle groundworks, steel, roof and fit-out as one project.
In Southgate, 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 Southgate: 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 Southgate
Southgate range: choose above
Kitchen extensions and side extensions in Southgate
The most common project is a single storey kitchen extension across the back of a 1930s semi, opening the old kitchen and dining room into one room onto the garden. The plots here often leave a gap down the side of the semi as well, which makes side and wrap-around extensions a natural fit. We dig and pour foundations to suit the ground, tie the new structure into the existing 1930s brickwork and install the steel beams needed where we open the back of the house into the new space.
A double storey extension adds a bedroom or en-suite above a larger kitchen below, and on these plots there is frequently space to do both. We match the roof line and the brick as closely as the original allows, upgrade insulation to current standards and manage the trades in sequence. Every extension is built to the building regulations and inspected by Enfield Council's building control as the work proceeds.
Housing in Southgate
Roughly 7,360 dwellings sit on the valuation list for Southgate. 53% are houses and 48% flats, and by age 18% predate 1919, 42% are interwar and 41% post-war. 28% of homes here are semi-detached; a rear extension on a semi in Southgate digs beside the attached neighbour, so one party wall notice is usual.
Planning history and the Mayor's levy for Southgate extensions
Of Southgate's homes, 41% were built after 1945, and houses on post-war estates were sometimes approved with conditions that removed permitted development rights. A condition like that makes a rear or side extension a planning application even on a street with no special designation. Search the Enfield Council planning register for the original estate permission and for any earlier extension to your house, since both affect what is allowed. An existing conservatory or extension also counts towards the permitted development limits, even when a previous owner built it and nobody remembers the date.
The larger plots of Southgate's semis and detached houses invite bigger schemes, and those can meet the Mayor's levy. Under the MCIL2 charging schedule Enfield is in Band 2, and a household extension large enough to be liable needs its exemption claimed, and the commencement notice submitted, before any work starts on site. Starting before the claim is made loses the exemption, and a missing commencement notice can bring a penalty. Put the levy forms on the same checklist as building control approval and the party wall notices, so all three are settled before the digger arrives.
Planning and permitted development in N14
Not every extension in N14 needs planning permission. Many single storey rear extensions fall under permitted development, but that depends on your specific house, whether it has already been extended and how close you are to a boundary. Larger, double storey or wrap-around schemes usually need a full planning application to Enfield Council. Parts of Southgate, including Southgate Green, are conservation areas, where side extensions and two-storey additions lose permitted development and need an application, and it is worth checking the council's Article 4 list for your address too. We assess your property first and tell you honestly which route applies.
Because a Southgate semi shares a party wall with the house next door, digging foundations near it or building off it brings the Party Wall Act into play, so you serve the right notices early, with the drawings we supply. Alongside that we handle the building regulations submission, which covers the structure, insulation, drainage and fire safety. Keeping planning, party wall and building control on track from the start avoids the delays that stall extensions.
Side return extensions in Southgate
Side returns belong to Victorian and Edwardian terraces, and only 18% of homes in Southgate predate 1919, so they are the exception here; most extensions run across the full rear width instead. Our side return extension page covers the build in detail, with build rates of £2,400 to £3,200 per m².
Double storey extensions in Southgate
Under permitted development a two-storey rear extension can go no more than 3 metres beyond the original rear wall and must stay at least 7 metres from the rear boundary, and in a conservation area it is not permitted development at all. Many gardens are too short for the 7 metre rule, so a double storey extension in Southgate often needs planning permission from Enfield Council. With 34% of homes here semi-detached or detached, the side of the house is often an option too. Planning Data records an Enfield Article 4 direction area covering the Southgate Green Conservation Area under the Enfield Borough Conservation Areas Article 4(1) Direction 2003 (council source). Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.
- Foundations, groundworks and steel frames
- Steel goalpost frames where the rear wall opens up
- Drainage diversion and build-over agreements with the water authority
VOA Council Tax stock of properties, March 2025, for Southgate and Southgate Green. Counts rounded by the VOA.
Why Southgate Homeowners Choose GS Renovation
Homeowners in Southgate choose GS Renovation because we run the whole extension, from foundations and steel to roof and final decoration, without juggling separate firms. We advise clearly on permitted development versus a planning application, give you the drawings for any party wall notice you serve on neighbouring semis, and keep Enfield Council's building control inspections on schedule. Our founder's 30+ years on the tools means we know how these interwar houses extend well.
- Insulation and thermal detailing to current regulations
- Building control inspected at foundation, damp course and steel stages
- Waste cleared as we go, not left piled up outside
Built a new extension at rear of property. Laid foundations, drainage, raised floor, new roof and completed all fixtures and interior decoration…
We loved working with George and Ibrahim and would highly recommend them. They have done splendid job on our new kitchen refurb which including new…
George was a great find. The job required re-plastering the walls before fitting acrylic panels. He also re-plumbed the shower waste under the solid…
FAQ
Frequently Asked Questions about House Extensions Southgate
What should I budget for house extensions in Southgate?
Budget for house extensions in Southgate as three amounts inside £2,000 to £2,800 per m² for a rear extension (indicative): the structural element, the finishing trades and the approvals. Approvals belong in the budget wherever the job includes building regulations approval from foundations to completion. GS Renovation lays the N14 quotation out the same way, so each element can be checked or deferred.
Will my Southgate extension need planning permission or is it permitted development?
Many single storey rear extensions on Southgate's interwar plots are permitted development, but if your home has been extended before, sits near a boundary, or you want a double storey or wrap-around, you will likely need a planning application to Enfield Council. We check your property's history and constraints, then advise the correct route before any work begins.
Does being in a conservation area change what I can add to my Southgate house?
Yes. A conservation area removes permitted development rights for side extensions, so a side or wraparound addition goes through a planning application to Enfield Council, and where an Article 4 direction applies further rights can be withdrawn. Confirm your Southgate address's status before any drawings. Building regulations approval is needed either way, whatever planning route the house takes.
Can we keep living in our Southgate house while the extension is built?
Most families do, because the new structure goes up outside the existing rear wall. Groundworks, walls and the roof happen with the kitchen still working. The difficult week or two comes when that rear wall is opened with steel and the kitchen is disconnected, so plan a temporary cooking area in another room for that stage and keep the route to the garden clear.
Do I need a party wall notice for a Southgate extension that does not touch the neighbour's wall?
Possibly. Digging within 3 metres of the house next door to a depth below its foundations requires one month's notice under the Party Wall Act, even if you never touch their wall. Southgate's interwar footings tend to be shallow, so a modern trench beside them often goes deeper. If next door agrees in writing, work proceeds; if they refuse, surveyors settle an award first, which adds weeks.
In what sequence is a single-storey extension built in Southgate?
Drainage and groundworks first, then the foundations, slab, walls, roof and glazing, so the new room is weathertight while the old back wall still stands. Only then is that wall propped and replaced with steel. Electrics and plumbing are run next, insulation is fitted to Part L, and plastering, flooring and the kitchen close it out. Enfield Council building control inspects at each stage.
Can a ground floor flat in Southgate be extended under permitted development?
No. Householder permitted development rights apply to houses, and a flat has none, so any extension goes to Enfield Council as a full planning application. With 48% of Southgate homes being flats, it is worth knowing before buying a garden flat. The freeholder's licence is also needed, the garden has to be demised to you under the lease, and the planning officer weighs the effect on light and outlook for the flats above.
Does the Southgate Circus conservation area change what an extension can be?
Yes, for any address inside it. Planning Data gives Southgate Circus a designation date of 2008, and within a conservation area householder permitted development is narrower: side extensions and rear extensions of more than one storey need a planning application, and cladding the outside is not permitted development. Look up the boundary, then read the Southgate Circus appraisal on the Enfield website before the designer starts, so the extension answers it from the first sketch.
Could a shared drain under a Southgate extension belong to the water company?
Quite possibly. Where two or more houses share a drain before it reaches the main sewer, that shared length has been a public sewer since private sewers were transferred to the water companies. Semi-detached pairs can share one at the back, and 34% of Southgate homes are semi-detached or detached. Building over or near it needs the water company's consent, so a camera survey of the drains comes before the foundation design.
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