AUST – HENDRY building surveyors advise that the Building Code of Australia (BCA) in Part A4 United Buildings sets out the criteria for when two or more buildings adjoining each other form one united building. There are significant advantages to building owners when uniting of building occurs due to the acceptance under the BCA.

Building Code of Australia Clause A4.1

BCA A4.1: When buildings are united
Two or more buildings adjoining each other form one united building if they—

(a)  are connected through openings in the walls dividing them; and
(b)  together comply with all the requirements of the BCA as though they are a single building.

The intent of the BCA is to allow two or more buildings that abut each other to be connected by openings in the adjoining walls which allows an occupancy or use to extend through more than one building. The connected buildings must then comply with all the requirements of the BCA as if they were a single building and the building is then called a united building.

As long as the buildings adjoin each other they may be united under the provisions of this clause without any regard to the boundaries of the allotments.

This clause only applies to buildings that adjoin each other. Buildings that are not adjoining cannot be united by means of bridges, covered ways, tunnels etc.

Fire doors would not have to be provided to the openings between the buildings if the floor area limitations of BCA Part C2 are not exceeded. For the purpose of this clause there is no limit to the size of openings between the adjoining buildings, and the abutting external walls can be considered as internal walls of a single building.

If the floor area limitations are exceeded by uniting the buildings then the openings may need to be protected by fire doors and the subject walls considered to be fire walls.

Where a united building involves different classes, the requirement for separation of these in accordance with BCA clauses C2.8 and C2.9 would still apply i.e. fire doors and fire walls between adjoining buildings will need to be provided if forming the boundary between separate classes.

Building Legislation Table

Refer to our Building Legislation table for further information on the building control process.