A material change of use is where there is a change in the purposes for which or in the circumstances in which a building is used, so that after the change the building or part of the building-

• is used as a dwelling, where previously it was not;
• contains a flat, where previously it did not, or a building containing flats is altered so that there are more or less flats than existed previously;
• is used as a hotel or boarding house, where previously it was not;
• is used as an institution, where previously it was not;
• is used as a public building where previously it was not;
• is not an 'exempt building' where previously it was.
• When a material change of use takes place, the building, or affected part, needs to be upgraded to satisfy certain important parts of the Building Regulations. Fire safety, ventilation provision and energy conservation applies to all the cases above. Structure, weather resistance, fire spread and sound insulation apply in specific cases.