Single and double storey extensions in Lewisham. Trusted, professional, 30+ years' hands-on experience.
GS Renovation designs and builds extensions across Lewisham, adding space to the bay-fronted Victorian and Edwardian terraces of Catford, Forest Hill and New Cross. With 30+ years working in SE6, SE23 and SE26, we handle everything from foundations and steel to the final fit-out, whether your project runs as permitted development or needs a full planning application.

The side return, that narrow strip beside the rear closet wing, is the most valuable space on a Lewisham terrace. Filling it in widens a cramped galley kitchen into a proper kitchen-diner running the full width of the house. We dig new foundations to suit the ground and any nearby trees, tie the new brickwork into the existing wall, and carry the original structure on a steel beam where the outside wall comes out.
A rear extension pushes the back of the house into the garden, often combined with the side return as a wrap-around. On these terraces we usually add generous rooflights or a lantern to bring daylight deep into the plan, since the middle of a terrace can be dark. Bi-fold or sliding doors open the new room to the garden. We manage the roof works, insulation and weathering so the extension is warm, dry and built to current standards.
Many single storey rear and side-return extensions in Lewisham fall under permitted development, meaning no full planning application, though we normally secure a lawful development certificate from Lewisham Council for peace of mind and future sale. Size limits, height and how close you build to the boundary all matter. Double storey extensions, anything facing the street, and work in a conservation area or on a listed building usually need planning permission.
Parts of Blackheath, Telegraph Hill and the streets around the Horniman Museum sit in conservation areas, where the council looks closely at materials and appearance. Whichever route applies, the build itself must meet building regulations, covering foundations, structure, insulation, fire safety and drainage, all inspected by building control. We advise early on the likely route for your address, prepare the drawings, and handle party wall notices where the extension affects a shared boundary.
Homeowners across SE4, SE13 and SE23 choose GS Renovation because we take an extension from first sketch to finished room as one team. We advise honestly on planning versus permitted development, engineer the structure properly, and coordinate the party wall side. With 30+ years on Lewisham terraces, you deal with one accountable contractor throughout.
George was brilliant. Lovely bloke, very reasonably priced and a perfectionist to boot. He completed our small kitchen renovation with care and great attention to detail. I've already recommended him to others.
Splendid job on our new kitchen refurb, including new flooring, moving the services, installing RSJ and preparing space for new back doors… George was always friendly, communicative and has an excellent attention to detail, ensuring everything is finished to a high standard.
Giorgio is an excellent and intelligent workman, and with very reasonable prices!… He paid a lot of attention to detail that is not common at all, and the final result was immaculate. Highly recommended!
FAQ
Every Lewisham project is priced on its own merits, as the cost of house extensions varies with the size, specification and condition of the home. We give a clear, itemised quote up front with no obligation. Call 07472 424 226 for an estimate tailored to your property. As a rough guide, house extensions in London typically starts from roughly £40,000 for a single-storey rear extension and rises with size and specification (indicative London ranges, MyBuilder and Checkatrade, 2026). Your figure depends on the size, specification and condition of the property, which is why we survey before quoting.
Timescales for house extensions in Lewisham vary with the size and complexity of the job. After our survey we give you a realistic schedule and keep you updated at every stage of the project.
With more than three decades of hands-on trade experience behind us, GS Renovation is a trusted choice for house extensions in Lewisham. You get one accountable team, transparent pricing, fully insured tradespeople and genuine aftercare on every project.
Many single-storey rear extensions in Lewisham fall under permitted development, but side returns, double-storey extensions and work in conservation areas usually need full planning permission. We assess your property and manage both the planning application and building control.
Yes. A large share of Lewisham's homes are Victorian and Edwardian terraced properties, and we renovate them regularly. We plan each house extensions around their particular characteristics, such as solid brick walls, rear closet wings, side returns and original period features, so the result suits the building and meets building control.
Often it will not. A single storey side-return or rear extension on a Lewisham terrace frequently falls within permitted development, so no full planning application is needed, and we obtain a lawful development certificate to confirm it. However, if your home is in a conservation area near Blackheath or the Horniman Museum, is listed, or exceeds the size limits, planning permission from Lewisham Council is required. We check your address first.
Absolutely. Our team works right across Lewisham and the SE4 area and neighbouring parts of South East London. Get in touch on 07472 424 226 to check coverage for your address.
Every Service, One Team
The same trusted team, 30+ years' hands-on experience and free, no-obligation quotes apply to every GS Renovation service in Lewisham. Explore what else we do locally:
Steel beam installation, RSJ and structural alterations.
Safe load-bearing wall removal with steel beam support.
Structural alterations, new openings and steel support.
Chimney breast removal with gallows bracket or beam support.
Open-plan kitchen, diner and living conversions.
Full refurbishments and whole-house renovations.
Bespoke kitchen design and installation.
Luxury bathroom and wet-room refurbishment.
Same Service, Nearby Areas
We carry out house extensions across Lewisham and the surrounding areas. Explore a nearby location:
Contact GS Renovation today for a free, no-obligation quote for house extensions in Lewisham.
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