What Is a Structural Opening? Removing Walls Safely in a Renovation
In short
A structural opening is a new or enlarged gap in a load bearing wall, such as knocking through a kitchen and dining room or opening the back of a house for an extension. Because the wall carries weight from above, the opening needs a beam designed by a structural engineer and approval from building control.
A structural opening is any opening formed in a wall that holds up part of the building. In London homes, that usually means knocking a kitchen through to a dining room, removing the chimney breast between two reception rooms, or opening the rear wall of a terrace to join a new extension. It is one of the most common requests in a renovation and one of the most important to get right.
Why it is more than knocking down a wall
A load bearing wall carries the weight of floors, walls and sometimes the roof above it, and passes that load down to the foundations. Remove part of it and the load has to go somewhere else. A structural opening redirects it through a new beam, usually a steel RSJ, which sits on solid bearings at each end and passes the weight down into walls or new columns that can take it.
The steps to form an opening safely
- Survey and design. A structural engineer inspects the wall, works out what it carries and produces calculations and a drawing for the beam, its bearings and any new foundations.
- Approvals. The work must comply with the Building Regulations and is inspected by building control. If the wall is shared with a neighbour, the Party Wall etc. Act 1996 may apply. Listed buildings also need listed building consent.
- Temporary support. Before any masonry is removed, the structure above is propped with adjustable steel props and needles so nothing moves while the wall is open.
- Forming the opening. The masonry is cut out carefully, bearings are prepared and padstones (concrete or engineering brick pads that spread the load) are set at each end.
- Installing the beam. The steel is lifted in, levelled and packed tight to the structure above.
- Inspection and fire protection. Building control inspects the steel and bearings. The beam is then boxed in with fire rated board or treated with intumescent paint, and the opening is plastered and finished.
What affects the cost and programme
The width of the opening, what sits above it, the condition of the existing masonry and access all affect the work. A wide opening across the back of a Victorian terrace, carrying two storeys and a roof, may need a steel frame with columns rather than a single beam. Getting the engineer involved early means the design is right first time and the beam can be ordered before the wall is opened.
How we handle structural openings on London’s Prestige projects
We coordinate the whole process for you: the structural engineer, the building control application, any party wall notices, the steel order and the installation. Openings are propped and formed by our own experienced team, inspected before they are closed up, and finished so the beam disappears into the ceiling line. You will see the result on our Prospect Road extension, where the rear of the house opens into one bright kitchen and living space. Read more about our extension service, or book a site visit and we will tell you what your wall is carrying and what opening it can take.
Common questions
Do I need building regulations approval to remove a wall?
If the wall is load bearing, yes. Building control must approve the beam design and inspect the work. Removing a non structural partition does not normally need approval, but it is worth checking with an engineer first.
Do I need planning permission for a structural opening?
Internal openings in a house do not normally need planning permission. Listed buildings are the main exception, where listed building consent is required for almost any alteration.
How long does it take to form a structural opening?
The physical work for a typical opening between two rooms is usually a few days once the steel is on site. Design, approvals and steel fabrication are what take the time, which is why they are arranged early.