Knocking down internal walls is one of the most common projects undertaken by those carrying out house remodelling projects.

Taking out an internal wall, fully or partially, is a great way to open up smaller rooms in one another in order to create large open plan family spaces. It is also necessary when incorporating a new extension into your existing layout.

However, before you get out the sledgehammer and begin knocking down internal walls, you need to ensure that your house will remain structurally sound during and after the wall has been removed. You should also be prepared for some disruption and dirt and be confident that any original features of the house are fully protected.

Do I Need Planning Permission When Knocking Down Internal Walls?

Knocking down internal walls is a job that usually falls under permitted development rights meaning you will not need to submit a planning application. However, those living in listed buildings will almost certainly need planning permission.

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

(MORE: Not sure if you need planning permission? Here are 20 things you can do without it)

Kitchen diner with double sided fireplace

In listed buildings it will be necessary to seek planning permission before removing internal walls, whereas this is more often a job that falls under permitted development. Image: Jeremy Phillips

Removing a Loadbearing Wall?

Some internal walls make up an integral part of structure of the house. Others are simply there to divide up the interior spaces into separate rooms and these are relatively straightforward to alter or remove.

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.

Knocking Down Internal Walls: Handy Checklist

To check whether or not a wall is load-bearing, your structural engineer or builder will check whether it is 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 wallsSome old houses rely on internal walls for ‘lateral support’, where the walls help to secure the external walls together.

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.

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

When removing structural walls – where a wall above is being supported by the wall beneath – it is necessary to insert a suitable lintel or beam or some other supporting structure to ensure the loads are safely transmitted to the ground. A structural engineer will be able to advise you on the best way to do this.

Removal of internal wall in kitchen extension

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

Knocking Down Walls: The Fire Regs

Before removing internal walls you should investigate whether it currently provides protection in the case of 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. Removing these walls will require Building Regulations consent, even if they’re not loadbearing.

On a similar basis, should you want to carry out a loft conversion 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.

Will Party Walls be Affected?

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.

Party walls in older properties aren’t always up to the job of supporting new loadings. Some were only single skin (one-brick thick or about 100mm), and may not be sufficiently strong for this new role. In this case, 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.

(MORE: How to extend and remodel terraced homes)

Will I Need a Completion Certificate?

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

No matter how well the work was done, without Building Control approval you could face complications. 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 family kitchen dining spaceRemoving the wall between a dining space and kitchen to create a larger, more useable space is a popular project. Image: Simon Maxwell

Knocking Down Internal Walls: Is a Structural Engineer Needed?

Victorian terrace renovation

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: Anthony Greenwood

Building Control will normally 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)

Boxing In Beams

Split level kitchen diner

Large differences in floor level can make for interesting split level designs once the dividing wall is removed. Image: Simon Maxwell

You might not have considered how the ceiling will be affected after knocking down a wall. However, when an entire load-bearing wall is removed, a it is important to realise that the new supporting beam is often be visible.

Steel beams need to be boxed in with plasterboard to comply with fire regulations. If a continuous ceiling is aesthetically important to you, one solution is to build a new suspended ceiling in order to conceal the beam.

Kitchen extension with sliding glazed doors

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 by Granit Architects

Another consideration is floor levels. In old houses, the floor heights often vary from one too to another and removing an internal wall can leave it horribly apparent that the floor levels in the newly conjoined rooms aren’t perfectly aligned — simply because they were never designed to meet.

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 Does it Take to Remove an Internal Wall?

Structural drawings in hand, a wall removal project 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 I Need a Lintel?

“Specifying steel members that are safe requires expertise that will be beyond the capabilities of most self builders,” says chartered structural engineer Simon Pitchers.

steel lintel over new doorway

A steel lintel resting on ‘padstone ‘engineering bricks supports the new opening in this kitchen extension project

“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.

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

Removing Internal Walls: Check Your Insurance

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, 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

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