Extension of a new building

In most cases, the extension of a property needs a building regulation application.

A domestic extension is generally defined as one increasing the floor space of the existing dwelling, and may be used for any purpose, such as sleeping, dining, lounging, studying, cooking, washing, sanitary accommodation, or purposes such as a garage, workshop, or store etc.

Building regulations will apply to both the new work and any enabling works within the existing property, such as new structural openings and dividing walls.

Certain extensions such as porches, conservatories and car ports may be exempt from building regulations.

Please refer to the LABC guide to extending your home for further information.

Health and safety

The building owner and the builder must ensure that any works to a building will not cause danger to health and safety. You should ensure that your proposal will not affect:

  • flues from heating appliances
  • any ventilation openings which serve heating appliance
  • ventilation openings to rooms 
  • any existing means of escape in case of fire routes

For more fire prevention information contact Dorset Fire and Rescue Services.

Loft conversions/roof space conversions

Generally all roof space conversions will be subject to the Building Regulations.

Roof space or attic conversions require a Building Regulation application where the intention is to provide additional accommodation in an existing roof void, which will be used on a regular basis.

Where the intended use is to store lightweight items such as suitcases, general household items, etc., then the provision of loose boarding is generally acceptable. In such cases the access would be expected to be made by ladder though an existing loft hatch in the ceiling of the area below. Remember that ceiling joists are not generally intended to act as a floor and are not designed to support heavy loads.

Therefore it is important to inform us and make a Building Regulation an application where the proposed work is anything other than light storage in a roof void.

Most people mistakenly believe that roof space conversions are simple. This is not the case. They should be designed and constructed by people aware of the health and safety aspects affecting building occupiers. The following must be considered and catered for in roof space conversions:

  • floors, certain walls and doors are required to be structurally able to resist the effects of fire for a specified period. Such provisions are essential to ensure safe means of escape in the event of fire or other emergency
  • the new floor and room layout requires a safe and easy exit route in the event of fire
  • the provision of an automatic smoke or fire detection system to give early warning of any fire is necessary
  • the provision of escape windows is an important aspect of life safety in such conversions
  • the structural adequacy of the "new floor" has to be designed and checked to ensure it can safely support the new loads paced upon it without suffering collapse or excessive deflection
  • ventilation is essential to most room areas to prevent unpleasant living conditions.
  • condensation, if not properly catered for especially in areas where it cannot be seen, can cause problems
  • the walls and roof of the roof space conversion require not only to keep out the rain and effects of damp, but also reduce heat loss
  • if a bathroom or shower room is to be included, additional ventilation measures will be required to prevent excessive condensation, and any waste water drainage will need to be properly formed
Page last updated: 13 October 2020
Help us improve poole.gov.uk
This is just for feedback on our website, not comments or questions about our services. Feedback on services will not be passed on. To tell us anything else, contact us.

Please don't include any personal or financial information.