House Extensions Bermondsey
Single storey rear and double storey extensions in Bermondsey, 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 in and around Bermondsey, from the pockets of Victorian terraces near Borough to the later houses elsewhere in SE16. We handle foundations, steelwork, roofing and fit-out, and we tell you honestly whether your project is permitted development or needs planning permission.
In Bermondsey, 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 Bermondsey: 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 Bermondsey
Bermondsey range: choose above
Rear and side-return extensions in Bermondsey
On Bermondsey's terraced streets, the classic project is a rear or side-return extension that squares off the plot and opens the ground floor to the garden. We dig and pour foundations to suit the ground, install the steel beams the new opening needs and tie the new roof into the existing structure, then fit out the space with services, glazing and finishes.
Many single-storey rear extensions on houses fall under permitted development, but that is never guaranteed in Bermondsey. Flats have no permitted development rights to extend at all. On a house, earlier extensions or planning conditions can use up or remove the rights, an Article 4 direction can remove them, and in a conservation area a side or two-storey rear extension needs permission, so a full planning application to Southwark Council follows. We assess your specific property first, then coordinate the drawings, the planning route where required, and the building regulations approval that every extension needs.
Housing in Bermondsey
Around 27,150 homes make up Bermondsey on the valuation list; 89% are flats and 11% houses, and 9% date from before 1919, 12% from between the wars and 73% from after 1945. Where most homes are flats, a flat in Bermondsey has no householder permitted development rights, so extending one needs planning permission and the freeholder's consent.
Sizing a Bermondsey terrace extension to Southwark's Householder SPD
Only 10% of homes in Bermondsey are terraced houses and 1% are semi-detached or detached, so a garden extension is a job for a small group of owners. For them, Southwark's Householder SPD says a terraced or semi-detached home can be extended to the rear by up to 3m in depth with a maximum height of 4m. The same SPD says rear extensions must not take up more than 50% of the total rear garden space. Measure the garden before the design starts. A short Bermondsey yard can hit the garden limit before it reaches the depth limit.
Floor area also sets the building control fee. Southwark's schedule has one charge for an extension less than 40sqm and another for an extension between 40 and 60sqm, so an extra metre of depth can move a scheme into the higher band. On the levy, Southwark's draft revised CIL charging schedule lists as exempt extensions to buildings of less than 100 square metres, except where the development will compromise one or more dwellings. Keep those thresholds in view when the drawings are settled.
Extending leasehold homes across SE16
Much of Bermondsey's stock is leasehold flats in warehouse conversions and new-build blocks, where a conventional garden extension is rarely possible and structural change is limited by the lease. Here we focus on what can be achieved within the demise, such as reconfiguring internal space or, in ground-floor maisonettes with outdoor rights, a modest addition agreed with the freeholder and managing agent.
Any external alteration in these blocks needs the freeholder's licence to alter, building-management consent and, in many cases, planning permission from the council because the change affects a shared building. We manage that consenting process alongside the construction, work to the party wall award where a boundary or shared wall is involved, and keep the acoustic and fire separation between flats intact throughout.
Kitchen extensions in Bermondsey
89% of homes in Bermondsey are flats, and a flat has no householder permitted development, so a ground-floor flat's kitchen extension needs planning permission from Southwark Council and the freeholder's consent. With so few houses here, the realistic kitchen gain in most Bermondsey homes is a better layout inside the flat rather than an extension. The fit-out is priced on its own page, kitchen renovation in Bermondsey; the build figures are in the table above. Double storey extensions belong to the few houses here.
- Planning applications and permitted development assessments
- Trial holes to set foundation depth near drains and trees
- Brickwork and mortar matched to the existing elevation
VOA Council Tax stock of properties, March 2025, for all 6 statistical areas in Bermondsey. Counts rounded by the VOA.
Trusted House Extensions in Bermondsey
Homeowners across Bermondsey choose GS Renovation because we give a straight answer on planning versus permitted development before any money is committed, then deliver the whole build with one team. Foundations, steel, roof and fit-out are all handled in-house, with building control managed for you. Our founder's 30+ years on the tools means no surprises.
- Foundation depth set after trial holes, drains and trees are checked
- Dust screens and floor protection in occupied homes
- Insulation and thermal detailing to current regulations
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 Bermondsey
How does your house extensions price in Bermondsey compare with a national firm's?
A GS Renovation price for house extensions in Bermondsey compares well with a national firm's because there is no head office to fund, and both should sit within £2,000 to £2,800 per m² for a rear extension (indicative). GS Renovation is the contractor doing the work at SE16, not a broker adding a margin. Compare the scope, including a Southwark Council building control inspection of the foundations before concrete is poured, not just the total.
Does my Bermondsey extension need planning permission or is it permitted development?
It depends entirely on the property. Some single-storey rear extensions on houses are permitted development, but flats have no such rights, and a side extension on a corner plot, a side or two-storey extension in a conservation area, or a house whose rights were used up by earlier extensions will need a full planning application to Southwark Council. Every extension needs building regulations approval regardless. We check your address and its history first, then confirm the correct route before the drawings are commissioned or the work is priced.
Can I extend a Bermondsey flat rather than a house?
Not under permitted development, which covers houses only, so extending a flat needs a full planning application to Southwark Council as well as building regulations approval. In practice the freeholder's consent comes first, since the lease normally controls the external walls and any garden land. A ground-floor flat with its own outside space is the usual candidate; upper flats rarely have anywhere to go.
What happens to drains under a Bermondsey extension footprint?
Find them before anything is drawn: lift the covers, run a camera through, and mark every line on the plan. Where the run turns out to be a public sewer, the water company decides whether you may build over it or alongside, and its answer can shrink the footprint. A private branch serving only your SE16 house can usually be diverted, provided the new route still falls properly under Part H.
Will digging foundations for my Bermondsey extension involve the neighbours?
Usually. Digging within 3 metres of the house next door, deeper than its own footings, is notifiable work, and the Party Wall etc. Act 1996 gives that owner one month's warning before excavation. Building right on the boundary line carries a separate notice. On a terraced SE16 plot the neighbouring wall is often close enough to the trench that notice is near certain, so serve it before the foundation design is fixed.
What insulation does a new Bermondsey extension have to meet?
Part L sets current standards for the new walls, floor and roof, and building control checks them at its inspection stages, so insulation thicknesses are drawn before foundations are dug. Glazing area counts too: a large rooflight or glazed rear wall can push the design over the limit and call for better performance elsewhere. The old rear wall becomes internal and is generally left alone.
Can a Bermondsey terrace in a conservation area extend at the rear without planning permission?
Do not rely on it. Nationally, a conservation area removes permitted development for side extensions, rear extensions of more than one storey and external cladding, while a single storey rear extension within the limits can survive unless a direction has withdrawn it. Southwark's Householder SPD goes further and says building one without planning permission is not applicable to homes in a Conservation Area. For a terrace in the Bermondsey Street Conservation Area, get the position confirmed by Southwark in writing before anything is built. A listed building is the exception: work that affects its character, inside or out, including an extension or taking out a wall or chimney breast, needs listed building consent from Southwark Council, and doing it without consent is a criminal offence.
Will a Bermondsey extension attract the Mayor of London's CIL as well as Southwark's?
Where CIL applies, both are collected. Southwark collects the Mayor of London's CIL at a current charge per square metre plus indexation, on top of the borough rates, and Southwark's own schedule sets different residential rates for Zones 1, 2 and 3. Southwark's draft revised charging schedule lists extensions of less than 100 square metres as exempt unless one or more dwellings are compromised. The planning agent confirms the position when the application is made.
How far into the garden can a basement under a Bermondsey extension go?
Southwark's Householder SPD says basement extensions should not extend under the rear garden beyond 50% of the garden depth from the principal rear wall. It also says planning permission is required for all homes to create a new basement or extend an existing one. On a short Bermondsey plot the basement may end well before the ground floor extension above it does, and the structural engineer we appoint designs the two structures around that line.
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