Building control for residential alterations

Conservatories and porches

A conservatory must have no less than three-quarters of its roof area, and no less than half of its external wall area, made of translucent material.

You do not need to make a building regulation application if your proposed conservatory or porch satisfies the points below:

  • the conservatory or porch must not exceed 30 square metres in floor area
  • the conservatory or porch should not be used as a kitchen, utility room or for any habitable purpose
  • all doors and windows in the existing building that are enclosed by the conservatory or porch must remain in place
  • safety glass must be provided to all windows within 800mm of the floor level and within 1,500mm of the floor level for doors, together with any side panels within 300mm of the door
  • if the conservatory or porch encloses a door or window that ventilates a habitable room, such as lounge, dining room, kitchen or bathroom, the conservatory or porch must be provided with 8,000 square millimetres background ventilation – trickle ventilators or air bricks with a "hit and miss" ventilator – and rapid ventilation – a door or window opening – at least 1/20th of the combined floor area of the conservatory or porch and the enclosed room
  • the conservatory or porch must not enclose the outlet of any boiler flue or ventilation duct
  • any existing manhole being built over must be sealed with a bolt-down double sealed cover, and any invert level of the drain should be observed

A building regulation application may be needed if any of the above items cannot be satisfied.

Building regulations approval and planning consent are different. You should check whether you need planning consent for your conservatory or porch.