If a bathroom or kitchen is to be provided in a room where there wasn’t one before, building regulations approval is likely to be required to ensure that the room will have adequate ventilation and drainage, and meet requirements in respect of structural stability, electrical and fire safety. 

Ground Floor WCsmall-bathroom

Any dwelling unit that has been constructed after 1999 will have a ground floor WC installed which has been designed to cater for any visiting wheelchair users.

During any re-fitting this WC should not be removed and the accessibility of the WC should not be made any worse as it would then be inadequate for future wheelchair users.

For these reasons, a Building Regulations application may be required if any alteration is to take place to an existing ground floor WC.

Floor Structure

If the use of a room is changed and could result in the load (weight) on the floor structure changing significantly work to strengthen the floor may be necessary.

For example, if a new bathroom suite is installed in a room where the floor structure is constructed of timber joists and boards, there is a significant risk of the floor being overloaded from the bath once it is full of water and in use. Therefore, work may be needed to strengthen such a floor.

A structural engineer or surveyor can assess the floor and determine this for you. If the floor does need to be strengthened they can produce the paperwork Building Control will require before you commence the work.


Each new room in a house should have adequate ventilation for general health reasons. The type of room will determine how much ventilation is required.modern-kitchen

When inserting a new internal wall care should 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 should also be taken to ensure that the existing room is ventilated adequately.

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.