​What to know about removing internal walls

Unless the building is listed, removing internal walls isn’t usually concerned with the planners. But you may need to apply for Building Regulations. Building control will visit your site for inspection and, should you meet the relevant requirements, issue a certificate.

Bear in mind that, in most cases, you will also need to consult with a structural engineer to design a suitable beam or supporting structure that allows the remaining loads to be safely transmitted to the ground.

While some walls simply divide up interior spaces, others are much more crucial for a building’s structure. And don’t believe anyone who says that you can simply tap a wall to hear if it sounds hollow – that is not how you investigate a load-bearing wall! 

Certain stud walls are load-bearing. Conversely, solid masonry internal walls aren’t always ‘structural’, as some were built as simple partition walls. If in doubt, rather get a structural engineer or building surveyor to do a thorough investigation and see whether the wall is taking weight of any of the following:  

• The roof. With older houses, the roof structure often relies on support from an internal wall. More modern roofs with W-shaped roof trusses, designed in the late 1960s, are designed to span right across the house without internal support.  

• The floor. It is quite rare that floor joists span more than four metres without support from an internal wall or beam. Check 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 usually continue on the next floor as bedroom walls. However, certain upstairs walls are offset or supported on a beam. Most modern houses have lightweight stud walls to the upper floors. 

• External walls. A lot of old houses rely on internal walls for ‘lateral support’, with the walls helping to secure the external walls together.

Internal wall demolitions are usually referred to as ‘knock-throughs’ by builders and can involve anything from cutting a new door hole to tearing down an entire wall. Generally, Building Control require a structural engineer to specify an appropriate beam or lintel. This should be done before getting quotes from builders so they know how much to charge.

Keep the following in mind when asking for quotes: 

• Don’t underestimate the amount of dust and mess involved with indoor demolition projects. It’s always worth having the builders erect dust screens across each room. 

• Make sure that quotes show costs for the repositioning of radiators, switches and electrical sockets.  

• Double check that all necessary plastering and decoration to areas of exposed masonry is included in the final price. 

• The old skirting boards need to be retained so that everything matches when the joinery is made good. 

• When a wall is removed, the new steel beam must rest on something at each end; thus, a small end section of the original wall (called a ‘nib’) may need to be left in place. 

When it comes to new door openings, the upper part of the old wall will be left in situ above the new opening (known as the downstand). But where an entire load-bearing wall is removed, a ‘clean sweep’ at ceiling level may not be possible due to the new beam normally being visible. 

Often when a wall is removed, it becomes apparent that the floor levels in the newly conjoined rooms either side aren’t perfectly aligned, as they were never designed to meet up. Even a few millimetre difference will stand out, which will require additional floor levelling work. In the same way, newly exposed wall surfaces may need to be fixed by a skilled plasterer.

After the structural engineer has calculated the loadings and discovered a suitable solution to satisfy Building Control, work on the site can proceed. But first, the masonry above must be temporarily supported while a slot is cut for the new beam or lintel. Usually, this slot must 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, such as padstone engineering bricks. The new opening can then be cut out underneath.

Keep in mind that party walls in older properties aren’t always meant to support new loadings. Some, like those built one-brick thick (about 100mm) may not be strong enough for this new role. If this is the case, it may be necessary to build new brick piers or install steel columns to support the new beam. This could mean having to excavate small foundations internally, adding major expense and disruption.

Generally, the entire project shouldn’t take longer than a week (but, of course, this depends on the size of the wall, access etc.).

The process of actually removing the wall and inserting a joist can be done in a day or two. Plastering of the newly exposed sections of wall and boxed-in joist should take no more than a day. Thereafter, painting can start.

The approximate prices for demolishing a wall and clearing debris into skip: 

• One-brick-thick wall – £40/m² 

• 100mm block wall – £20/m² 

• Timber stud partition wall – £41/m²

• To open up a kitchen/dining room with a square opening 1.8m wide to load-bearing wall – £1,200.

But as we said: keep safety in mind and ensure you employ a seasoned professional during all stages of removing an internal wall.

Let’s see how to go about Separating rooms without walls.