Removing walls to open up living space, with engineer-designed steelwork
Structural Alterations and Knock-Throughs
A structural alteration, or knock-through, removes or alters a load-bearing wall — typically to join a kitchen and dining room — and requires structural calculations from an engineer, a supporting steel beam sized to the load, and Building Regulations approval before and after the work.
Definition
What Structural Alterations covers
Structural alterations cover any work that changes a load-bearing element of a building, most commonly removing an internal wall to create open-plan living space. The work involves temporary propping, forming the opening, installing a steel beam (or other structural solution) designed by a structural engineer, and making good the surrounding structure, all inspected and signed off under Building Regulations.
Suitable for
- Households wanting to open up a kitchen and dining or living room
- Removing or altering a chimney breast or partition wall
- Forming a wider opening between two rooms while retaining some support
- Properties where a structural survey confirms the wall can be safely altered
Not suitable for
- Alterations to a shared party wall structure without the necessary party wall agreement in place
- Work on a listed building's structural fabric without the required listed building consent
Process
How the work is carried out
- 01
Structural survey
Assessing the wall, what it supports, and the loads involved, ahead of instructing an engineer.
- 02
Engineer's calculations
A structural engineer sizes the steel or other structural solution and produces calculations for Building Control.
- 03
Building Regulations and party wall
Submitting a Building Regulations application and serving party wall notice if the work affects a shared wall.
- 04
Construction
Temporary propping, forming the opening, installing the steel and making good, with a Building Control inspection before the work is covered up.
Typical timescale
A single knock-through with one steel beam typically takes one to two weeks on site including making good, though this depends on the span, what is being supported, and how much redecoration is needed afterward.
Cost guidance
Structural alterations typically cost £2,500–£8,000 per opening in our area, including the steel beam and engineer's calculations, with span, load and access driving the range. We provide an itemised quotation once the structural engineer's design is confirmed.
Limitations and exclusions
- Structural engineer's calculations are provided by a qualified engineer, not written in-house, and are a required part of the Building Regulations submission
- Party wall matters where a shared wall is affected are a legal matter between neighbours; we can recommend a party wall surveyor but do not act as one
- Decoration and redecoration beyond making good the immediate area of work is quoted separately
Areas we cover
Structural Alterations across Sussex, Surrey, Kent and South London
Local property styles, planning authorities and neighbourhood coverage for structural alterations in each town we work in.
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FAQs
Structural Alterations FAQs
Do I need planning permission to remove an internal wall?
Usually no — removing an internal load-bearing wall is normally a Building Regulations matter rather than a planning one, provided the property isn't listed and the work doesn't affect the external appearance. We confirm the position for your property at survey.
How do I know if a wall is load-bearing?
Load-bearing walls typically run perpendicular to floor or roof joists, sit above a wall or support on the floor below, or align with the roof structure — but this isn't reliable to judge by eye, so we assess it on-site and confirm with a structural engineer before any work starts.
Will Building Control need to inspect the work?
Yes. A Building Control inspection is typically needed once the opening is formed and the steel is in place, before it's covered up with plaster or boarding, and again at completion.
Discuss your structural alterations project
Tell us about the property and what you have in mind, and we'll arrange a site visit.
Last reviewed 2026-07-28.