Change Of Use
Where a material change of use occurs a Building Regulations application should be made. These are where:
- the building is used as a dwelling, hotel, boarding house, institution or public building where previously it was not, or,
- the building contains a flat where previously it did not, or,
- the building was previously exempt and will not be after the change, or
- a building containing at least one dwelling is converted to provide a greater or lesser number of dwellings than it did previously (the term dwelling includes a flat).
Other useful departments-
Planning, Environmental and Consumer Protection and Dorset Fire and Rescue Services 
Directgov