When it comes to renovating a house, it is sometimes necessary to knock down internal walls. It might be that the existing layout is unsuitable for modern living, or perhaps the existing rooms suffer from a lack of natural light.
If you are planning on knocking down internal walls, it requires detailed thought and careful planning to ensure that the property remains structurally sound and that any period character is retained.
Do I Need Planning Permission to Remove a Wall?
You can normally knock down an internal wall under your permitted development rights (if in doubt, do check with the planners before you begin).
You may need to also make a Building Regulations application. Building control will visit you to inspect the work and, providing you fulfil the requirements, issue a certificate.
It would be wise to also consult a structural engineer to design a suitable beam or some other supporting structure so the remaining loads are safely transmitted to the ground.
If your property is listed, you will need to consult your local planning department.
Does the Wall Protect You from Fire?
Before demolishing an internal wall it’s also worth considering whether it protects you from fire. For example, where the loft has been converted, the walls around the staircases offer protection, allowing you to escape in the event of a house fire. Altering these walls will again require Building Regulations consent, even if they’re not load-bearing.
On a similar basis, should you want to convert the loft in the future, partition walls that separate entrance halls from reception rooms are best left intact, since they form a ready-made fire escape corridor to comply with Building Regulations.
Is it a Party Wall?
In terraced or semi-detached houses, where new beams need to rest in the party walls that separate you from the neighbours, it’s also advisable to first talk to a specialist Party Wall surveyor to ensure compliance with the relevant legislation.
Retrospective Building Regulations Approval
While there may be no apparent defects, if there is no completion certificate to prove that the work was properly carried out, this could be an accident waiting to happen.
Here, the best course of action is to contact Building Control and arrange an inspection. At worst you may need to obtain a Regularisation Certificate, which is the equivalent to making a retrospective Building Regulations application.
This normally requires a certain amount of physical opening up of the work to establish that it is structurally sound and verify compliance; the cost of making good afterwards will be down to you.
Be prepared for the dust and mess created by knocking through
Identifying a Load-bearing Wall
Some internal walls are fundamental to the structure of the house, whereas others simply divide up the interior space and are relatively straightforward to alter or remove.
Can You Tap a Wall to See if it is Load-bearing?
Contrary to popular belief, tapping a wall to see if it sounds hollow is definitely not enough in the way of investigation.
Some stud walls are load-bearing. On the other hand, solid masonry internal walls aren’t always ‘structural’ — some were built as simple partition walls.
To ascertain whether or not a wall is load-bearing, your structural engineer will check whether it is taking the weight of any of the following:
- The roof: In older houses the roof structure often relies on support from an internal wall. More modern roofs with W-shaped roof trusses (introduced in the late 1960s) are designed to span right across the house from the main wall to another without internal support
- The floor: Floor joists rarely span more than about four metres without support from an internal wall or beam. Look for nail runs in floorboards to identify the direction the joists are running in (usually at right angles to the direction of the floorboards)
- Other walls: Ground floor walls often continue above as bedroom walls. However, sometimes upstairs walls are offset or supported on a beam. Most modern houses have lightweight stud walls to the upper floors
- External walls: Some old houses rely on internal walls for ‘lateral support’, where the walls help to secure the external walls together.
Knocking Down a Wall: Need to Know
Building Control normally requires a structural engineer to specify an appropriate beam or lintel, and this should be done before getting quotes from builders so they know how much to charge.
Ensure the below are factored in from the outset:
- You can never overestimate the amount of dust and mess involved — have the builders erect dust screens across each room
- Check that quoted prices allow for the repositioning of any radiators, switches and electrical sockets
- Ensure all necessary plastering and decoration to areas of exposed masonry is included in the price
- The old skirting boards should be retained so that everything matches when the joinery is made good
- When a wall is taken out, the new steel beam will have to rest on something at each end, so a small end section of the original wall (known as a ‘nib’) may need to be left in place
- For new door openings, the upper part of the old wall will be left in situ above the new opening (known as the downstand)
Ceiling and Floor Levelling
Where an entire load-bearing wall is removed, a ‘clean sweep’ at ceiling level may not be possible as the new beam will normally be visible.
Bear in mind that steel beams need to be boxed in with plasterboard to comply with fire regulations. If a continuous ceiling is aesthetically important, one solution is to build a new suspended ceiling to conceal the beam.
Once a wall is removed it often becomes horribly apparent that the floor levels in the newly conjoined rooms either side aren’t perfectly aligned, because they were never designed to meet.
Even a small difference of a few millimetres will stand out, requiring additional floor levelling work. Similarly, newly exposed wall surfaces may require the attention of a skilled plasterer.
A steel lintel resting on padstone engineering bricks supports the new opening
How to Knock Down a Load-bearing Wall
Before any demolition work is carried out, the masonry above must be temporarily supported while a slot is cut for the new beam or lintel.
This slot normally needs to extend either side of the opening with a bearing of at least 150mm. To spread the load, additional support will be needed under the ends of the lintel. The new opening can then be cut out underneath.
Bear in mind that party walls in older properties aren’t always ideal for supporting new loadings. Some were built one-brick thick (about 100mm), and may not be sufficiently strong for this new role. In which case, it may be necessary to build new brick piers or install steel columns to support the new beam — which could mean having to excavate small foundations internally, adding significant expense and disruption.
How Long Will it Take?
Once you have obtained structural drawings, if required, the whole project should take no longer than a week — although obviously this will vary a little depending on the size of the wall, access etc.
The actual removal of the wall and insertion of a joist can be done in a day or two, while plastering of the newly exposed sections of wall and boxed in joist should take no more than a day. Finally, painting can be carried out.
Specifying Steel Lintels
“Self-design can be tempting for a self builder. However, specifying steel members that are safe requires expertise that will be beyond the capabilities of most self builders,” says chartered structural engineer Simon Pitchers.
“A professional steel beam design from a chartered structural engineer can be purchased for a few hundred pounds. Many manufacturers of proprietary steel lintels will employ engineers who can design their products to suit specific situations. They will often provide this service free of charge, again avoiding the need for a self-builder to attempt this specialist exercise.
Visit the Institution of Structural Engineers’ website to find out whether a structural engineer is needed for your project.
Cost of Knocking Down a Wall
|Cost of Associated Work|
Cost (incl materials and labour)
|Demolish wall and clear debris into skip:|
|Quoin up and make true the end of the wall||£65/m²|
|Open up a kitchen/dining room with a square opening 1.8m wide to load-bearing wall||£1,200|
|Add on more for the following:|
|Form a new single door opening in an internal wall (cut opening, fit concrete lintel, quoin up jambs, fit 50x100mm softwood frame, stops and architrave, and make good finishes):|
Are You Insured?
It is worth bearing in mind that your existing home insurance policy may not cover works undertaken as part of a major home improvement project.
Homebuilding & Renovating has partnered with leading insurance specialist Self Build Zone to provide bespoke solutions at market-leading rates.