House Extensions Kennington
Single storey rear and double storey extensions in Kennington, 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 Kennington, adding space to the Georgian, Regency and Victorian homes of SE11 without spoiling their character. We handle foundations, steelwork, roofing and the full fit-out as one accountable project.
In Kennington, 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 Kennington: 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 Kennington
Kennington range: choose above
Rear and side return extensions in Kennington
The most popular extension on a Kennington terrace is the rear or side-return infill, filling the narrow strip beside the original closet wing to widen a cramped kitchen into an open-plan kitchen-diner. These period plots can be tight, so the engineer designs foundations that respect the neighbours' walls and existing drainage, and we then form the opening with an engineer-designed steel beam signed off by Lambeth building control. Glazed roofs and rooflights pull daylight deep into the plan.
A double-storey rear extension can add a bedroom or bathroom above the new ground-floor space, which changes the loading and calls for heavier foundations and steel. We match brickwork and detailing to the existing Georgian or Victorian elevation so the addition sits comfortably. Throughout, we protect the retained house, manage the muck-away within these SE11 streets and keep the property secure and weathertight while the shell goes up.
Housing in Kennington
The stock in Kennington runs to roughly 8,500 dwellings, 82% of them flats and 18% houses, built 28% before 1919, 12% between 1919 and 1939 and 60% after 1945. Most homes here are flats, and a flat in Kennington has no householder permitted development rights, so extending one needs planning permission and the freeholder's consent.
Kennington rear extensions and the spatial character test
The Kennington Conservation Area Statement says rear extensions are only likely to be acceptable where they would not harm the spatial character of the area. On a terrace, that character is likely to include the gaps between rear returns as seen from the neighbouring houses and gardens. The Lambeth Local Plan adds that infill extensions alongside closet extensions or rear returns should generally be single storey on heritage assets. A Kennington owner planning a side-return infill on a heritage asset should draw it as one storey from the start. Show on the drawings how the rhythm of returns along the terrace survives.
The same statement says no buildings in the Kennington Conservation Area are subject to an Article 4 Direction. So a modest single storey rear extension to an unlisted house may still be permitted development, where the spatial character test does not apply. A side-return infill is different: in a conservation area it counts as a side extension, outside permitted development, and so does any rear extension of two storeys. Where an application is needed, Lambeth says a householder application should get a response in 8 weeks, so build that into the programme before a start date is agreed.
Planning and party walls around SE11
Whether your Kennington extension is permitted development or needs a full planning application depends entirely on the property. Many modest rear extensions fall under permitted development, and a single-storey rear extension keeps that right in a conservation area, within its limits, unless an Article 4 direction removes it. Side extensions and two-storey rear extensions lose permitted development in Lambeth's conservation areas, which cover a large part of Kennington, and a listed house needs listed building consent as well. In those cases an application to Lambeth Council is required, and we coordinate the drawings and supporting information with your architect or designer.
Extensions almost always trigger party wall matters, because you build up to or along the boundary shared with the adjoining owner and excavate near their foundations. The Party Wall Act then requires you, as building owner, to serve formal notice; we supply the drawings it needs and work with your surveyor so any award is agreed before groundworks begin. Separately, the structure itself is signed off under building regulations by Lambeth building control, which is a different process from the planning decision.
Kitchen extensions in Kennington
82% of homes in Kennington are flats, and a flat has no householder permitted development, so a ground-floor flat's kitchen extension needs planning permission from Lambeth Council and the freeholder's consent. Most kitchen extensions here are on the 18% of homes that are houses. The fit-out is priced on its own page, kitchen renovation in Kennington; the build figures are in the table above.
Double storey extensions in Kennington
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 Kennington often needs planning permission from Lambeth Council. It is a job for the 18% of homes that are houses; a flat cannot add a storey this way. The Kennington Conservation Area Statement says rear extensions are only likely to be acceptable where they would not harm the spatial character of the area (council source). Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.
- Drawings and the structural engineer's design coordinated for you
- Levels, drainage and landscaping made good around the new build
- Foundations, groundworks and steel frames
VOA Council Tax stock of properties, March 2025, for Lambeth Walk & North Kennington and Oval. Counts rounded by the VOA.
Why Choose GS Renovation in Kennington
Kennington extensions live or die on the detail, and GS Renovation manages the lot: engineer-designed steel, correct foundations, the planning or permitted development route, party wall coordination and Lambeth building control. One team with our founder's 30+ years on the tools means fewer handovers, brickwork that matches the period elevation and a build that respects your neighbours and the conservation setting.
- One point of contact from first survey to handover
- Building control inspected at foundation, damp course and steel stages
- 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…
George was brilliant. Lovely bloke, very reasonably priced and a perfectionist to boot. He completed our small kitchen renovation with care and great…
George always kept to commitments and arrived on time. He offered helpful suggestions during his initial visit and promptly provided a reasonably…
FAQ
Frequently Asked Questions about House Extensions Kennington
How much should house extensions in Kennington cost?
The cost of house extensions in Kennington is typically £2,000 to £2,800 per m² for a rear extension (indicative), and the SE11 survey decides where in that range your job lands. The biggest mover is what the survey finds: the depth of neighbouring Kennington foundations decides how deep the new footings go. GS Renovation shows the Lambeth Council building control fee on its own line, and the written figure follows within days of the visit.
Will my Kennington extension need planning permission or is it permitted development?
Some rear extensions in Kennington qualify as permitted development, and a single-storey rear extension can still do so in a conservation area unless an Article 4 direction applies. Much of SE11 sits within a Lambeth conservation area, where side and two-storey extensions need a planning application to Lambeth Council, and a listed home needs listed building consent too. We assess your specific property first, then handle the right route and the separate building regulations sign-off.
Why do extension foundations sometimes go deeper in Kennington?
Because where clay is near the surface it shrinks in dry summers and swells in wet winters, and shallow footings move with it, while in many Kennington streets river-terrace gravel sits over the clay instead. The engineer sets the depth for the soil a trial hole finds and for any trees nearby, whose roots dry clay further. Lambeth building control inspects the open trench before the concrete goes in. Deeper digging next to the neighbour's house can also bring in a party wall notice.
Can a ground-floor Kennington flat be extended?
Sometimes, but not under permitted development, which covers houses and not flats. A flat extension needs a planning application to Lambeth Council, plus Building Regulations approval, plus the freeholder's written consent under the lease. Where the garden belongs to the flat, check the lease plan too. Settle the lease question first, since without it the other approvals are wasted effort.
Does a Kennington extension on the boundary need a party wall notice?
Very often. If foundations are dug within 3 metres of the neighbour's building and deeper than theirs, one month's notice is required. On a terrace with a narrow plot that is almost certain. Your neighbour may consent or dissent. After a dissent, surveyors produce an award before work starts, so notice goes out as soon as the foundation design is fixed.
What brings daylight into a Kennington extension behind a tall terrace?
Glazing in the roof, since the tall house blocks light from the side. Rooflights and a lantern above the deepest part of the new room bring light where windows cannot. Part L sets insulation standards for the new roof and walls, which limits how much glazing can go in without compensating elsewhere. Rooms at lower-ground level need this planning even more.
Is pre-application advice worth it for a Kennington rear extension?
Where the scheme tests the spatial character line, it usually is. Lambeth charges a higher householder pre-application fee for a house or flat in a conservation area or a locally listed or listed building than for one outside those designations, so confirm the address's status first. Bring measured drawings showing the neighbours' returns, because the officer's view turns on how the extension sits in the terrace.
How does Lambeth's building control charge differ for one and two storey extensions?
Lambeth lists a single storey domestic extension up to 40m2 and a two storey domestic extension up to 40m2 as separate items, each with its own total charge. For a Kennington house the storeys and floor area should be fixed before the application goes in. Given the Local Plan steer toward single storey infills on heritage assets, confirm the planning answer before paying for a two storey building regulations design.
Can a Kennington extension go below the garden as well as into it?
Only within Lambeth's basement policy. It supports full basement extensions beyond a house's footprint only where, among other tests, generally no less than 70 per cent of the rear garden stays free of subterranean development. An extension and a basement both take ground at the back, so plan them together rather than one after the other. Measure the garden before asking an engineer to design anything below ground.
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