Single and double storey extensions in Sidcup. Trusted, professional, 30+ years' hands-on experience.
GS Renovation designs and builds extensions across Sidcup, where interwar semis and detached houses sit on the generous plots that suit rear and side additions. With over 30 years of experience in DA15 and the Bexley borough, we handle foundations, steelwork, roofing and full fit-out, guiding you through permitted development or a planning application to the council.

The wide plots common across Sidcup give real scope for extending, and the most popular projects are single or double storey rear additions that open the back of a 1930s semi into a large kitchen-diner. Side-return and wrap-around extensions make use of the space beside the house, and where the original rear wall comes out we install a steel beam sized by a structural engineer to carry the load above.
We start with proper foundations and groundworks suited to the ground conditions, then build up in brick or block to match the interwar character, tie in the new roof, and complete the internal fit-out. Because a semi shares a boundary and party wall with the neighbour, excavating near that line usually brings the Party Wall Act into play, which we handle for you.
Many single storey rear extensions on Sidcup houses fall under permitted development, meaning no full planning application is required, though this depends on the size, height and whether previous extensions have used up your allowance. Double storey additions, work to the front, or anything affecting the street scene usually needs planning permission from Bexley Council, and we advise which route applies before any drawings are finalised.
Whichever route the property takes, every extension must satisfy building regulations, and Bexley Council building control inspects the foundations, the steelwork, the insulation and the drainage as the work proceeds. We manage the applications, the inspections together, so you have one team accountable for both the paperwork and the build from start to finish.
Sidcup homeowners choose GS Renovation because we build extensions that suit the interwar stock and the generous plots of DA15, not off-the-shelf boxes. One team handles design, foundations, steel, roofing, party wall matters and the full fit-out, and we tell you honestly whether your project is permitted development or needs planning permission from Bexley Council. Over 30 years stands behind every build.
I had a bathroom refit which I was very pleased with and I then went on to get my kitchen refitted as I was so happy with the way he worked. Even…
George always kept to commitments and arrived on time. He offered helpful suggestions during his initial visit and promptly provided a reasonably…
Excellent service. George's knowledge and skills are the best in the market. He knows what he is doing, does really high quality work, gives good…
FAQ
It moves, and you see the movement immediately. Because the house extensions quotation for a Sidcup home is itemised, a change to the specification at DA15 is priced against the same lines rather than renegotiated wholesale. GS Renovation issues a written variation and waits for your approval. That protects both sides on every Bexley project. Ring 07472 424 226 and GS Renovation will explain how a variation at your DA15 address in Sidcup is agreed. 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.
Always. Running house extensions without a programme is how a Sidcup project drifts, so the sequence for your DA15 home is agreed before anyone arrives. GS Renovation keeps one team on the Bexley site rather than splitting it across jobs, which is the practical reason the dates hold. Variations are re-programmed and agreed in writing with Bexley Council notified where needed. Ring 07472 424 226 and we will explain how a DA15 programme is held in practice.
Because it is inspected and certified, not simply declared finished. Bexley Council inspects the structural stages of house extensions at your DA15 property before anything is concealed, and the completion certificate is handed to you at the end. GS Renovation also appoints the structural engineer where the design requires one. That paperwork is what a buyer's solicitor asks for when a Sidcup home is sold anywhere in Bexley. The Bexley certificate arrives with the DA15 handover pack.
Many single-storey rear extensions in Sidcup fall under permitted development, but side returns, double-storey extensions and work in conservation areas usually need full permission. We assess your DA15 property and manage both the Bexley Council application and building control.
Yes, and we would rather explain why than quietly add a margin. The variables in an interwar semi-detached Sidcup home are condition and concealment, both checked at the DA15 survey before GS Renovation commits a figure. The structural work itself is priced much the same. The Bexley Council element is shown separately on every Bexley quotation. Ask on 07472 424 226 what actually moves a house extensions figure at a DA15 property of that particular age.
Many single storey rear extensions on Sidcup houses are permitted development, so no planning application is needed, but it depends on the depth, the height, how close it sits to boundaries and whether earlier extensions have used your allowance. Double storey or front additions usually need planning permission from Bexley Council. Either way the work must meet building regulations. We assess your property and confirm the correct route before drawings are finalised.
Yes, boundaries are not something we price against. House extensions runs across Bexley and into South East London, so an address on the edge of Sidcup or over towards Bexleyheath is no harder to service. GS Renovation will say plainly if travel makes it impractical. Ring 07472 424 226 with the DA15 postcode and we will confirm. The survey that follows is free and carries no obligation. Aftercare is no more difficult a few streets further out.
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 Sidcup. Explore what else we do locally:
Same Service, Nearby Areas
We carry out house extensions across Sidcup and the surrounding areas. Explore a nearby location:
Free, no-obligation quote for house extensions in Sidcup. Rated 4.9 from 31 reviews on MyBuilder, fully insured, and building control handled for you.