Building standards technical handbook 2019: domestic

The building regulations always apply where construction occurs, unless exempted by regulation 3, and construction includes alterations and extensions as well as entirely new buildings. When there is a conversion it will be necessary to seek a warrant and possibly to undertake works to improve the standards of the building, or part of the building, concerned.

Regulation 4 and schedule 2 set out what changes of occupation or use of a building are defined as conversions and for which the owner must obtain a warrant before making the change. The warrant for a conversion will only be granted if the standards set out in regulation 12 are achieved and this might well require building works.

Those changes of use or occupation listed in schedule 2 are those which are considered critical due to the risks involved. They relate to:

Type 6 in schedule 2 refers to the significant alterations in the type and the number of expected occupants. A significant alteration of type could be considered to occur when there was a significant change in the mobility, the familiarity with building, or the awareness of danger, of the occupants. For example, significantly different types would include:

A significant alteration in number could be considered to occur where it amounted to an increase greater than 25%.

Type 9 in schedule 2 refers to allowing access by the general public where previously there was none. Access by the general public refers to permitting members of the general public to enter a building during opening hours and allowing them to access all parts of the building, other than those parts restricted to staff only.

For conversions it is the intention that the standards achieved in the converted building should be broadly similar to those achieved by entirely new buildings. Schedule 6 to regulation 12 guides the verifier as to where discretion is expected to be necessary. It identifies those standards where it is not expected to be reasonably practicable to have existing buildings fully comply. However for these standards improvement of the existing building is expected where it is reasonably practicable. This means that matters such as thermal insulation now have to be improved even if meeting the full standard is not practically achievable. Guidance on what is normally reasonably practicable is given in schedule 6 and in the individual sections. Guidance is also given on the treatment of historic buildings.

It is also relevant that the requirements of other legislation, for example regulations made under Health and Safety at Work or licensing legislation, will apply to changes of use, so that risk assessments of changed circumstances will provide protection to the occupants of buildings.