Single and double storey extensions in Westminster. Trusted, professional, 30+ years' hands-on experience.
GS Renovation designs and builds extensions across Westminster, working with the grand stucco terraces, period mansion blocks and prestigious townhouses of Mayfair, Pimlico and Paddington. With more than 30 years in W1, W2, SW1, WC2, NW8 and W9, we handle groundworks, steel, roofing and full fit-out on properties that are often listed or within a conservation area.

Westminster plots are tight and precious, so extensions here tend to reclaim every usable inch. On the Georgian and Victorian houses around Marylebone and Paddington, a rear closet wing and side return often become a single open kitchen-diner, carried on a steel beam and built off new foundations dug to suit the ground and any neighbouring structures. We survey drains, party walls and existing footings before a spade goes in.
Whether your project is permitted development or needs a full planning application depends entirely on the property. Listed buildings and conservation areas across SW1 and W1 usually rule out permitted development, meaning an application to Westminster City Council. We advise honestly on which route applies, so you know the planning position before committing to a design.
Because so much of Westminster is protected, extension design is a conversation with the council as much as an engineering task. We prepare schemes that respect the stucco frontages, mansion-block symmetry and roofscapes the borough guards closely, and we manage the planning application and, where relevant, listed building consent alongside the building regulations submission for the structural work.
Party wall matters are almost unavoidable here. New foundations near a boundary and beams bearing onto shared walls trigger notices under the Party Wall Act, and mansion-flat extensions in NW8 or W9 need the freeholder's licence to alter. We coordinate neighbours, freeholders and managing agents, then deliver the full build, from groundworks and steel through to roof, glazing and a complete interior fit-out.
Homeowners across Westminster choose GS Renovation because an extension on a listed or conservation-area property demands more than a builder. We manage the planning application to the council, party wall notices, engineer-designed steel and building control, then build the lot in-house. Thirty years across W1, SW1 and NW8 means we know what this borough will and will not allow.
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 Westminster 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.
Most house extensions projects in Westminster take between two and eight weeks depending on the scope and whether structural work is involved. We provide a clear programme before work begins so you know exactly what to expect.
GS Renovation knows Westminster's homes and how to renovate them properly. We handle the structure, the services and the finishes, deal with building control for you, and leave you with work that is certified, guaranteed and built to last.
Many single-storey rear extensions in Westminster 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 Westminster's homes are period, Georgian and listed properties, and we renovate them regularly. We plan each house extensions around their particular characteristics, such as conservation and listed-building rules, solid walls and original period features, so the result suits the building and meets building control.
It depends on the property. Many Pimlico houses sit within a conservation area or are listed, which usually removes permitted development rights and means a planning application to Westminster City Council, sometimes with listed building consent. Elsewhere, a modest rear extension may fall under permitted development. We check your property's status first and tell you exactly which route your project needs.
We cover the whole of Westminster and the W1 area and the surrounding Central London. If you are nearby and not sure, just call 07472 424 226 and we will tell you straight away.
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 Westminster. 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 Westminster and the surrounding areas. Explore a nearby location:
Contact GS Renovation today for a free, no-obligation quote for house extensions in Westminster.
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