Open-Plan Conversions Westminster

GS Renovation creates open-plan and broken-plan spaces in Westminster's period homes, from kitchen-diners in Marylebone townhouses to knock-throughs in Pimlico and Belgravia. We combine grand period rooms into flowing, light-filled spaces while respecting the structure that holds these Georgian and Regency buildings up.

In Westminster, a knock-through finished as one room typically costs £3,000 to £8,000 or more, including the steel beam (indicative London ranges, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Westminster: the structural engineer we appoint designs the steel, we install it, and building control signs it off.

How the job runs

1. Free site survey at your Westminster address, covering the walls, services and floor levels, and an itemised quote.
2. The engineer we appoint sizes the beam, and the work is registered with Westminster City Council building control or an approved inspector. On a shared wall you serve the party wall notice as building owner; we supply the drawings.
3. Props in, opening cut, beam on padstones; then floors, heating and electrics are joined up.
4. Building control inspects the steel before it is covered. We finish the room, and the completion certificate follows.

Open-plan conversions in Westminster townhouses

The classic Westminster knock-through joins two reception rooms, or a kitchen and dining room, into one generous space that suits how these homes are lived in today. In the terraces of Belgravia and Marylebone the dividing wall between those rooms is usually load-bearing, so we do not simply open it up. A structural engineer sizes a steel beam to span the opening, bearing onto padstones, and we prop the floors above while the wall is removed in stages.

Not every Westminster homeowner wants a single vast room, and broken-plan layouts suit these tall, formal interiors well. We keep a sense of separation with a wide supported opening, a part-height return, or slim Crittall-style glazed dividers that let light travel through while defining a snug or study. In leasehold mansion-block flats around Paddington and W9, many internal walls are non-structural partitions, which gives more freedom to reconfigure, though the freeholder's consent still applies.

Housing in Westminster

The stock in Westminster runs to roughly 132,230 dwellings, 91% of them flats and 9% houses, built 48% before 1919, 10% between 1919 and 1939 and 40% after 1945. Where most homes are flats, opening up a flat in Westminster changes the protected route from the bedrooms to the front door, so building control checks the escape before any wall comes out.

Opening up a Westminster flat that was altered before you bought it

In Westminster 91% of homes are flats, and 48% of homes were built before 1919, so the flat you plan to open up may already carry decades of earlier changes by other owners. Before a new layout is designed, find out what the last owner did. If a wall has already gone without approval, the structural engineer we appoint has to design around steel nobody has checked, and a buyer's solicitor may later ask for a certificate that does not exist. Clearing that up is far easier while the floor is open than after it is finished.

Westminster accepts building control applications online as full plans, building notice or regularisation. Regularisation is the route for work done in the past without approval: the District Surveyors look at what is there, which can mean exposing old beam ends and bearings, and certify it if it complies. We schedule that opening up alongside the new work, so one set of props and one round of dust covers both. The regularisation certificate for the old work and the completion certificate for the new then sit together in the file for any future sale.

Consents for open-plan living in Westminster

Opening up a Westminster home is internal work, so it is controlled under the Building Regulations rather than planning permission. Westminster City Council's building control inspects the beam, the padstones and the fire and ventilation arrangements before signing off. If your townhouse is listed, as many are in Mayfair and Belgravia, removing original walls or cornices may need listed-building consent, so we establish the property's status before any design is finalised.

Where the wall being opened is a party wall shared with a neighbouring house, the Party Wall Act applies and you serve notice as building owner before work begins, standard practice in the linked terraces of SW1 and W1. In a mansion-block flat we help you secure the freeholder's licence to alter, coordinate with the managing agent, and meet the building-management rules on sound insulation between flats. Whichever your home, we line up every consent up front.

• Making good, plastering and decorating the finished space
• Open-plan kitchen-diner conversions
• Rooflights and glazed roofs to bring light deep into the plan

VOA Council Tax stock of properties, March 2025, for all 24 statistical areas in Westminster. Counts rounded by the VOA.

If you are weighing up options for your Westminster property, it is worth reading home renovation in Westminster, our Westminster area guide, side return infills, garage conversions, open-plan conversion across London and Kitchen Island Guide.

Why Choose GS Renovation in Westminster

Westminster homeowners choose GS Renovation for open-plan work because we deliver the whole project through one accountable team. We build the structure to an engineer's design and install the steel, and finish with the plastering, flooring and Crittall glazing. The drawings for your party wall notices, help with the freeholder's licence, and building control sign-off are all handled, with tidy working in your period home and our founder's 30+ years on the tools behind every job.

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.