Knocking down an interior wall can be a great way to create a big, airy, open-plan living space. It’s cheaper than building a new extension. Demolishing the wall between a kitchen and dining room is a popular home improvement, for example. But before you start swinging a sledgehammer, there are some important things to consider.
Is it load-bearing?
It’s crucial to find out if the wall you want to knock down is load-bearing, that is, whether it supports parts of the house. It could support a roof, floor, another wall above or either side. It’s often difficult to tell the difference between a loadbearing and non-loadbearing wall. If you’re in doubt, it’s best to call a structural engineer or architect.
“It’s often a case of reviewing the entire building, starting in the roof and working your way down to see if walls at first and ground floor are load-bearing,” said Sam Farzam, director of Marbas Engineering Consultancy. If you remove a load-bearing wall it could make your home unstable.
“Load-bearing walls provide structural stability. If you damage the structural integrity of a building, it requires a lot of work to fix," said Sam.
Supporting beam
If the wall is load-bearing, it doesn’t mean you can’t knock through, but you will need to replace it with a suitable supporting structure. Building Control will ask you to appoint a structural engineer to advise on the project.
Installing a steel beam
Sam said: “Structural engineers produce detailed drawings and calculations that the Building Control inspector will review before building work starts. A steel support beam of between two to three metres can cost less than £200. It’s the building work involved in installing the beam that costs more.”
Before any demolition to a load-bearing wall is done, the masonry above must be temporarily supported with acrow-props and ‘strongboys.’
Electrics and plumbing
The next step is to consider whether the wall contains any electrics or pipes which will need to be re-routed. “When a builder knocks a hole through a wall they will look at the position of light switches and sockets to trace electrical wiring. Pipes are generally under the floor boards,” said Sam.
Removing an entire wall may not be necessary. It may be possible to just cut an opening and keep parts of the wall. “This where a clever architect can be invaluable to help decide if it’s worthwhile removing an important structure or if you can design around it and still achieve the clients’ aims," said RIBA-chartered architect, Scot Masker of Hampshire and Berkshire-based Pro Vision.
Building consents
Planning permission isn’t usually needed for internal alterations unless you live in a listed building. However, an application must be made for Building Regulations if you’re removing an internal wall (regardless of whether it is load-bearing or not) or creating a new opening.
Knocking down an interior wall
Building Control inspectors will then make site visits and compare the work with your structural engineer’s specification (if it is load-bearing) and Building Regulations for issues such as structural stability and fire safety. The inspector will issue a completion certificate if it complies. When you sell your home, you’ll need this important piece of paper.
Party walls
In terraced or semi-detached homes, where new supporting beams need to rest in shared or party walls the best course is to first speak to a specialist Party Wall Surveyor who can advise you on the relevant law.
Ceilings and floors
Ceilings and walls may need to be re-plastered or patched. “There may be some settlement and localised cracking above the area where a wall was knocked out. We always advise having a bit of budget in place to carry out repair work such as cracking to plaster,” said Sam.
If you knock through to create a kitchen-diner, there may be tiles on the old kitchen floor and wooden boards or carpet in the dining room. Ideally, you will replace flooring, so it all matches up.
Re-laying a floor after extending
