What is a structural alteration?
A structural alteration changes how a house carries its loads, most often by removing a load-bearing wall and replacing it with a steel beam. It is how kitchens and dining rooms become open-plan, and how extensions are joined to the original house.
How much does a structural alteration cost in Westminster?
In Westminster, a structural alteration typically costs £5,750–£12,500 for a typical knock-through with steel beam, including VAT at 20% (standard rate). Prices across London are typically 30% above the UK average for this kind of work, which is reflected in the range for Westminster. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical knock-through with steel beam | £5,750–£12,500 |
| Higher specification | £12,500–£15,500 |
The biggest cost drivers are:
- Moving radiators, sockets and pipes
- Span of the opening
- Floor and ceiling repairs
- What sits above the wall
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a structural alteration in Westminster?
Whether you need planning permission depends on your house and its location in England. In England removing a load-bearing wall does not need planning permission but does need building regulations approval with an engineer’s calculations. If the beam bears on a party wall, a party wall notice must be served.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
From survey to sign-off, the job normally involves:
- Fire protection to the steel
- Structural engineer’s calculations and drawings
- Building control application
- Temporary propping
- Making good, plastering and flooring repairs
- Building control sign-off
How long does it take?
The build itself usually takes 1 to 2 weeks on site for a typical knock-through. Before that, surveys, drawings and approvals usually take 6 to 12 weeks, longer if the council asks for changes.
Building in Westminster
Space is at a premium in London, so homeowners often build out into the side return or up into the roof rather than move.
We work across Westminster and neighbouring areas such as Bermondsey, Brixton and Battersea. Postcodes we cover in Westminster include SW1.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about structural alterations in Westminster
How much does a structural alteration cost in Westminster?
In Westminster, a structural alteration typically costs £5,750–£12,500 for a typical knock-through with steel beam, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
How do I know if a wall is load-bearing?
Only a survey can confirm it. Walls that carry floor joists, roof loads or walls above are load-bearing. We check on site and the engineer confirms.
Do I need building regulations approval?
Yes. Removing a load-bearing wall is building work that needs approval, with calculations for the beam.
Do I need a party wall notice?
In England and Wales, if the beam sits in a party wall, yes.
How long does a structural alteration take in Westminster?
Typically 1 to 2 weeks on site for a typical knock-through. Design and approvals beforehand usually take 6 to 12 weeks.