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Internal Walls

Planning Permission

You should not need to apply for planning permission for internal alterations including building or removing an internal wall.

If you live in a listed building, however, you will need listed building consent for any significant works whether internal or external.

Building Regulations

If you wish to build a new internal wall, remove an internal wall, or form an opening in an internal wall, building regulations will normally apply.

There are typically two types of internal walls:

  • Load Bearing - where the wall provides separation between rooms and is also required to transfer loads from other parts of the structure, roof and floors etc., down to the foundations - view further details below.
  • Non-Load bearing - walls that provide separation between rooms and are not required to transfer loads

New Internal Wall(s)

Work to provide a new internal wall generally requires approval under the Building Regulations 2000

In the case of conversion projects:

  • adequate separation - in terms of fire resistance and thermal insulation - should be provided between the new habitable space and the remaining space.
  • Any door provided in such a wall should have adequate fire resistance and be self-closing. Depending on the use of the new habitable room, the new separating wall may also need to provide sound insulation.

Removal of Internal Wall(s)

Care should be taken before removing any internal wall. These walls can have a number of functions that could affect the building and the safety of the occupants within the building.

Further information

The following pages give an indication of some of the elements normally required to satisfy the requirements of the Regulations for internal walls:

The following common work section gives an indication of another element normally required to satisfy the requirements of the Regulations for internal walls:

Fire Safety

Building a new wall to subdivide a room or create a new room can affect the means of escape from fire.  If in doing so a situation is created whereby the route for leaving an existing or new room is only possible through another room then an egress (escape) window from the existing or new room (inner room) will be needed as well as, possibly, one or more smoke alarms. 

If the floor level of the inner room is greater than 4.5m above ground level (as with the top floor of a typical three storey house for example) the use of an egress window may not be safe and therefore an alternative solution will need to be sought.  This may well be one that does not create an inner room situation in the first place.

Some walls around stairways (typically in houses 3 storeys or more in height) need to have fire resistance to ensure a fire in one of the rooms off of the stairway doesn’t unduly affect the means of escape from other rooms in the house.  In other houses (such as in two storey houses) the walls may not need to have any particular fire resistance, but would still afford some protection to the stairway by containing the fire and smoke for a period of time.

The impact of the removal of an internal wall on fire safety should be carefully considered. In two storey houses, the removal of such a wall could normally be compensated by the provision of mains powered interlinked smoke alarms and egress windows from the other rooms off the stair. However, in houses of three storeys and greater this compensation may not be sufficient. The exact features needed will vary on a case by case basis.

A new wall (including any door leading through it), which separates a room from the stairway may need to have adequate fire resistance (typically in three storey houses) and, in the case of a door, be self closing.

Load Bearing Walls

A load bearing wall is one which supports other elements of the building, such as (and most commonly) the:

  • Roof - part of the roof structure which would include the ceiling joists within the loft area are sometimes supported from internal walls.
  • Wall above - there is possibility that if another wall sits directly above then it could be supporting that wall
  • Floor Joists - floor joists are sometimes built into or sitting on top of an internal wall

These are the most common parts of a building an internal wall could be helping to support, however there are other things to look for. An example could be where the chimney stack has been removed on the ground floor.  A beam has been placed across the underside of this stack to support it, which then sits on an internal wall to transfer the load down to the foundation.

A structural engineer or surveyor can be employed to determine if the wall is load bearing and then design a beam to cater for these loads.

Beam(s)

Structural Support

The beam should be designed to cater for the loads that the wall was originally taking. This beam then needs to be supported on two other supports (typically walls) that are capable of taking the loads to foundations. Any new beam should normally have at least 150mm bearing (overlap onto the existing wall) on each side of the opening and the existing wall beneath the bearings are likely to need to be strengthened to prevent crushing of them. This may require the installation of an area of dense concrete (cast in-situ or pre-cast), known as a padstones to spread the load. The size of padstones will vary depending on the circumstances of the case in hand it is advisable to speak to a structural engineer or surveyor before starting any works.

Fire Safety

If the beam is steel then it should normally be protected against fire so that it will have 30 minutes resistance to fire (if measured in a standard test). There are different ways that this may be achieved, but most common is the use of two or more layers of properly fixed plasterboard - the thickness of which will depend on the manufacturer's specification.

If an exposed timber beam is preferred then a calculation is generally required to demonstrate how much inherent fire resistance it has - dependent on it's size and species of timber. A concrete beam, which would normally have steel reinforcement inside it, would generally has adequate fire resistance properties, providing the steel inside is adequately covered by the concrete.

Sound Insulation

If a new wall is to separate a bedroom or room containing a WC from another room it will need to have improved sound insulation installed. 

There are many different products and solutions on the market and gaining advice from a manufacturer or Building Control Body is recommended.

Structural Support

Internal walls can be constructed of different materials such as timber frame, metal frame or masonry.  When constructing a new internal wall it should be supported by something strong enough underneath, whether the wall is load bearing or not.

Non-Load Bearing

With timber or metal frame walls it is normally acceptable to support them on the existing floor joists (not the floor boards), either by providing a double floor joist underneath, if they run parallel, or across the existing joists if the floor joists run at 90° to the wall. (In both cases, there may be circumstances where additional support may be needed therefore it is strongly advisable to ask a structural engineer or surveyor to check the adequacy of the floor joists). 

With masonry walls, which are heavier, the floor joists may need to be larger or, more likely, it may be necessary to provide a new beam.  If the flooring is of a concrete construction it will be difficult to ascertain the thickness and strength of the floor therefore, unless it is certain, the lightest possible construction is advisable.

Load Bearing

The support needed for a load bearing wall is likely to be more extensive, depending on the load the new wall will be supporting. 

For a new wall in an upper storey of a typical house, providing support to the wall from the existing floor joists is unlikely to be adequate as the self-weight of the wall plus the load it supports will probably be more than the joists are capable of supporting.  This may mean introducing a new beam, which itself should be adequately supported.

For a new wall at the ground storey of a typical house, the support needed will depend on the existing floor construction.  If it is a timber floor then similar considerations for a new wall in an upper storey will be relevant (see above).  Alternatively a new foundation can be provided beneath the floor, although the work in doing this may be difficult due to space constraints beneath the floor.  A new foundation is also likely to be needed even if the floor is of concrete construction, unless the floor can be shown adequate to carry these new loads.

A new wall built off a new ground bearing foundation or slab should be provided with a damp proof course (DPC), at least 150mm above ground level. If the wall is formed through an existing concrete floor care should be taken to ensure continuity of the damp proofing by linking the damp proof course with any damp proof membrane in the existing floor. This is a difficult procedure to accomplish with damaging the membrane or floor.

If the new wall passes through an existing timber floor, the key thing to pay attention to is to ensuring that any new timber that is in contact with or supported by the new wall is above the line of the damp proof course. Also, if there is ventilation in the void under a suspended timber floor then air bricks in the wall are likely be needed to maintain air flow through the void.

Ventilation

When inserting a new internal wall care must be taken not to make any other matters, such as ventilation worse.

If a new room is being created as a result of  the addition of an internal wall then care must also be taken to ensure that the existing room is ventilated adequately. The type of room will determine how much ventilation is required.

The general rules for ventilating a room are:

Purge - this is achieved by opening the window. The opening should have a typical area of at least 1/20th of the floor area of the room served, unless it is a bathroom which can be any openable size.

Whole Building - this is also known as trickle ventilation which can be
incorporated in to the head of the window framework, or by some other means.
The area varies on the type of room:

  • Bathroom – 4000mm²
  • All other rooms – 8000mm²

Both of these forms of ventilation are normally required, however alternative approaches to ventilation may also be acceptable, subject to agreement with the Building Control Body.

Mechanical extract fans

Any new kitchen, utility room, bath/shower room or WC with no openable window should be provided with a mechanical extract fan to reduce condensation and remove smells.  The necessary performance of these extract fans is normally measured in litres per second (l/s) as follows:

  • Kitchen - 30l/s if placed over the hob and 60lt/s if place elsewhere.
  • Utility room - 30l/s
  • Bath/shower - 15l/s with a 15 minute overrun (after the light is switched out) if there is no openable window.
  • WC - 6l/s with overrun.

Alternative rates may be applicable if the ventilation is running continuously.

Disclaimer

This is an introductory guide and is not a definitive source of legal information. Read the full disclaimer here.

This guidance relates to the planning regime for England. Policy in Wales may differ. If in doubt contact your Local Planning Authority.