Do I need a structural engineer to remove a wall?
If the wall holds up anything above it, yes. This guide explains how to tell, what the engineer produces and what has to happen before the wall comes down.
The short answer
You need a structural engineer to remove a wall if it is load-bearing, meaning it supports floors, a roof, another wall or a chimney above. The engineer designs a beam and its supports so the loads are carried safely once the wall has gone, and Building Control will ask for those calculations before approving the work.
If the wall is a genuine non-load-bearing partition, you usually do not need an engineer. It is still worth having one confirm it, because in older London houses the difference is not always obvious, and a wrong guess shows up as sagging floors and cracked ceilings upstairs.
How to tell if a wall is load-bearing
There are reliable clues, but none of them is proof on its own. An engineer looks at several together, often lifting a floorboard upstairs or looking into the loft to see what the wall is actually doing.
Be careful with timber stud walls in Victorian and Edwardian terraces. Many were built as braced partitions that help carry the floor above, and some have sagged onto the wall over a century so it now carries load whether it was meant to or not.
- Floor joists above run across the wall and rest on it, rather than running parallel to it
- The wall lines up with a wall on the floor above
- It is a solid brick spine wall running front to back through the middle of the house
- It supports a chimney breast, a stair trimmer or a beam end
- It is an original wall in a house where the roof has struts or purlin props landing near its line
What the structural engineer actually does
The engineer starts with a load take-down: working out what the wall carries from every floor, wall and roof area above. From that they size the new beam, which is usually a steel section in a typical London house, sometimes timber or a steel flitch plate for lighter loads and shorter spans.
The design does not stop at the beam. Each end needs a sound bearing, normally a concrete or engineering brick padstone that spreads the concentrated load into the masonry. The engineer checks the wall or pier below can take that point load, and in some cases checks the foundation too. They also set out temporary propping so the builder can remove the wall safely.
The result is a set of calculations and a marked-up drawing that your builder and Building Control both work from. Our load-bearing wall opening design covers all of this, and every design passes our three-step quality control with final sign-off by our Head of Engineering. If you want to understand what is inside the package, our guide to structural calculations explains it in plain terms.
Downstand or flush beam?
One of the first decisions is whether the beam can sit below the ceiling as a visible downstand, or has to be hidden within the floor depth. A downstand beam is simpler, usually smaller and avoids disturbing the floor above. Most open-plan kitchens in London terraces have one, often lined up with a kitchen island or the edge of a rooflight.
A flush beam sits within the depth of the floor joists, so the ceiling stays flat. It is achievable, but the existing joists then have to be cut and hung off the beam on hangers or shelf angles, which means lifting floorboards upstairs and more work for the builder. A flush beam is often deeper or heavier than a downstand doing the same job, because it has less depth to work with.
Tell the engineer early which you want. Changing from downstand to flush after the calculations are done means a redesign and, often, a fresh submission to Building Control.
Building Control approval
Removing a load-bearing wall is a structural alteration, so it falls under the Building Regulations, specifically Part A. You need to apply to Building Control, either through your council or a private approver, before the work starts. The engineer's calculations form the core of that application.
During the work, the Building Control inspector will usually want to see the steel in place before it is boxed in and fire protected. Once satisfied, they issue a completion certificate. Keep it safe. When you sell, the buyer's solicitor will ask for it, and a missing certificate for a knocked-through room is one of the most common delays in London sales.
Removing a wall can also affect fire safety. In a house with a floor two or more storeys up, the hallway and stair often form a protected escape route, and opening the kitchen into it may need other measures. Building Control will advise on this alongside the structure.
Party walls, chimneys and other complications
If the new beam bears into a wall you share with a neighbour, you are cutting into a party structure. Under the Party Wall etc. Act 1996 you must serve a party structure notice at least two months before that work starts. Our guide to the Party Wall Act and structural works covers the notices and timings in more detail.
Chimney breasts are another common catch. If the wall you are removing supports a breast on the floor above, or you plan to remove a breast at the same time, the design has to deal with both. The chimney breast removal guide explains the options. Walls in flats bring their own issues too, because the floor above belongs to someone else and the lease usually requires freeholder consent.
What happens on the day
A competent builder will follow the engineer's propping guidance closely. The order matters, because the loads from above must always have somewhere to go.
- Install temporary props, and needles through the wall where the engineer specifies them
- Remove the wall down to the level of the new bearings
- Build or set the padstones and let the mortar or concrete gain strength
- Lift in the beam and pack it tight to the masonry above with slate or steel packers and dry-pack mortar
- Remove the props only when the engineer's conditions are met
- Arrange the Building Control inspection, then fire protect and plaster
Frequently asked questions
Can my builder size the beam instead of an engineer?
Building Control will expect calculations from a competent designer, which in practice means a structural engineer. Builders often have good instincts about beam sizes, but they rarely check bearing stresses, the masonry below, deflection limits or the loads coming from a roof two floors up. An undersized beam may look fine for years before cracks appear, so it is cheaper to get the design right at the start.
Do I need planning permission to remove an internal wall?
Usually not. Removing an internal wall in a house is normally not development that needs planning permission. The exceptions are listed buildings, which need listed building consent for internal changes, and some flats, where the lease requires the freeholder's consent. You will still need Building Regulations approval if the wall is load-bearing, which is a separate process from planning.
Can I remove a load-bearing wall in a flat?
Often yes, but there are more parties involved. The lease usually prohibits structural alterations without the freeholder's written consent, and the flat above may be affected, so party wall notices can apply. The engineer needs to understand what the wall carries from the floors above, which can mean access to neighbouring flats. Building Control approval is required in the same way as for a house.
What if a wall has already been removed without approval?
This is common, especially in houses that have changed hands several times. An engineer can inspect the beam and bearings, open up where needed, and check whether the work is adequate. If it is, Building Control can issue a regularisation certificate. If not, the engineer designs the remedial work. Our retrospective structural assessment is set up for exactly this situation.