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Knocking Down Internal Walls: A Complete Guide

knocking down internal walls
(Image credit: Dulux)

Knocking down internal walls is a job undertaken by many people renovating, remodelling homes with dated layouts in order to transform them. The removal of internal walls is also often necessary when building an extension.

By removing internal walls, natural light can come flooding in, spaces can be opened up to become more suitable for family life and a more sociable, flexible way of living can be achieved.

However, knocking down internal walls is a job that has structural implications and before you begin you must understand the role of the walls you have marked for removal. 

In order to ensure the overall stability of your home is not compromised, there are a few checks you will need to make. 

You should also be prepared for some disruption and dirt and be confident that any original features of the house are fully protected.

Do You Need Planning Permission to Knock Down Internal Walls?

Knocking down internal walls is not a job that usually needs planning permission as it usually falls under permitted development — meaning there is no need to submit a planning application. 

However, if your house is listed you will almost certainly need planning permission.

You may well need to make a Building Regulations application too. Building control will visit you to inspect the work and, providing you fulfil the requirements, issue a certificate.

(MORE23 things you can do without planning permission)

knocking down internal walls

Knocking down internal walls to create a light, bright and sociable kitchen diner is one of the most popular jobs amongst those remodelling old houses. This kitchen is from Trend Interiors Bedrooms, Bathrooms and Kitchens. (Image credit: Trend Interiors)

Can Loadbearing Walls be Removed?

Top Tip

Despite what you might have been led to believe, simple knocking on a wall to see if it sounds hollow is definitely not enough in the way of investigation. 

A loadbearing wall is one that plays an important structural role in the construction of a house. Loadbearing walls support another element of the house, such as the roof or a wall on an upper storey. 

Others walls carry no loads and are simply there to divide up the interior spaces into separate rooms — these are relatively straightforward to alter or remove.

It is also important to note that some stud walls (timber frames covered with plasterboard) are loadbearing, whilst solid masonry internal walls aren’t always ‘structural’ — some were built as simple partition walls.

Tiled flooring leading in to kitchen diner from outside

Knocking down internal walls is often required when creating extensions, as well as during remodeling jobs. (Image credit: The London Tile Co)

How to Tell if a Wall is Load-bearing

It is always best to check with a builder or structural engineer before removing any wall. They will be able to tell you whether or not the wall is loadbearing, supporting 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. 

When removing structural walls – where a wall above is being supported by the wall beneath – it is vital that a suitable lintel or beam or some other supporting structure is fixed above the new opening to ensure the loads are safely transmitted to the ground. A structural engineer will be able to calculate the type and size of lintel required. 

Before any demolition work is started, the masonry above the wall must be temporarily supported while a slot is cut to take the new beam or lintel that will be required.

This slot will usually have 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. 

Once the lintel is in place, the new opening can be cut out underneath.

Although removing non-loadbearing walls is usually a straightforward job, it is still wise to consult a structural engineer or builder before you begin. 

In both cases, you will need to prepare yourself for the dust and mess that will be created. 

Supports in place during removal of a wall

A structural engineer will be needed to provide the necessary calculations when removing a load-bearing internal wall (Image credit: Jeremy Phillips)

Before removing internal walls you will need to check whether they are currently providing any protection in the case of a fire.

For example, where a loft conversion has been carried out, the walls around the staircase offer protection, allowing you to escape in the event of a house fire. Removing these walls would require Building Regulations consent, even if they’re not loadbearing.

If you plan on carrying out a loft conversion in the future, consider that partition walls that currently separate entrance halls from reception rooms are best left intact, since they form a ready-made fire escape corridor to comply with Building Regulations.

Will Removing a Wall Affect Any Party Walls?

In the case of many terraced or semi-detached houses, the new beams required to support the walls where walls have been knocked down may need to rest on party walls that separate your house from the neighbours'. In this case it is advisable to consult a specialist Party Wall surveyor to ensure compliance with the relevant legislation.

In some older properties, party walls are not strong enough to support any new loadings — some were only single skin (one-brick thick or about 100mm). 

If this is the case in your property, it will 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.

(MOREHow to extend and remodel terraced homes)

knocking down internal walls

If the removal of your internal walls is going to affect any walls shared with neighbouring properties, a Party Wall Agreement will be required. This kitchen from Trend Interiors Bedrooms, Bathrooms and Kitchens has been partially opened up to a dining space beyond.  (Image credit: Trend Interiors)

Should I Get a Completion Certificate After Removing an Internal Wall?

With no completion certificate to prove that the internal wall removal work was properly carried out, problems could lie ahead.

Even if the work complies with all the relevant building regulations, without Building Control approval you could face complications when you come to sell on. Contact Building Control and arrange an inspection as soon as you can. The worst case scenario is that you will be asked 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.

Open plan kitchen diner by Resi Architects

Removing the wall between a dining space and kitchen to create a larger, more usable space is a popular project (Image credit: Resi)

Do I Need a Structural Engineer When Knocking Down Internal Walls?

Building Control will often require you to hire 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.

Before work begins, consider the following:

  • Removing internal walls creates a huge amount of dust and debris — ask your builders to put up dust screens to contain the mess
  • Factor in the costs of repositioning of any radiators, switches and electrical sockets
  • Ensure all necessary plastering and decoration to areas of exposed masonry is included in the price
  • Take care not to damage original features and ensure original skirting boards are retained so that everything matches when the joinery is made good
  • When removing a load-bearing wall, the new steel beam that will take the load it once supported will have to rest on something at each end.  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)

Broken plan kitchen diner

Taking out the wall between the kitchen and dining rooms in this Victorian house renovation project has increased the sense of light and space (Image credit: Anthony Greenwood)

How to Box in Supporting Beams

Have you considered how the ceiling will look after the wall has been removed? When an entire load-bearing wall is removed, it is important to realise that the new supporting beam will often be visible.

There are a few ways of dealing with this but steel beams do need to be boxed in with plasterboard in order to comply with fire regulations

If you would prefer the look of a continuous ceiling, one common solution is to build a new suspended ceiling in order to conceal the beam.

knocking down internal walls

Any new steel beams must be boxed in to comply with fire regs — often this boxing in can be turned into an interesting architectural feature — here it works to define the living area in an open plan space.  (Image credit: Carpetright)

You might also need to think about floor levels. In old houses, the floor heights often vary between rooms so removing an internal wall can leave it obvious that the floor levels in the newly conjoined rooms are not the same. 

In the case of large differences in floor level, a split level design can become a design feature, but where the difference is small (millimetres or centimetres, for example) some floor levelling work will need to be undertaken.

How Long Will it Take to Knock Down Internal Walls?

Once you have all the relevant structural calculations and approvals, removing an internal wall should take no longer than a week — although obviously this will vary depending on the size of the wall, access etc.

Removing an internal wall, along with the 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 another day. Finally, painting can be carried out.

Will a Lintel be Required to Remove an Internal Wall?

“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.

Open plan kitchen-diner leading to garden

The addition of an extension often requires the removal of both load bearing and non-supporting walls, as was this case with this modern addition (Image credit: Granit Architects)

How Much Does it Cost to Knock Down an Internal Wall?

Although quotes vary according to area and the scale of the job, use the below as a guide when budgeting.

Demolition

  • One-brick-thick wall - £40/m²
  • 100mm block wall - £20/m²
  • Timber stud partition wall - £41/m²

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

Plus the following:

  • Full removal of wall with no remaining ‘nibs’ - £200
  • To reposition a radiator - £120
  • To reposition two wall sockets and light switches - £200
  • Party Wall surveyor - £300

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):

  • One-brick-thick solid wall - £640
  • Stud partition - £485
  • Hanging a single door - £94

Will I Need to Change my Home Insurance After Removing an Internal Wall?

Your existing home insurance policy may not cover works undertaken as part of a major home improvement project, such as removing internal walls.

Homebuilding & Renovating has partnered with leading insurance specialist Self Build Zone to provide bespoke solutions at market-leading rates.

Get a quote now to protect your project.