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 (united buildings) occurs due to the acceptance under the BCA.

Building Code of Australia Clause A4.1 (United Buildings)

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 (united buildings) by openings in the adjoining walls which allows an occupancy or use to extend through more than one building. The united buildings must then comply with all the requirements of the Building Code of Australia (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 deemed as united buildings under the provisions of this BCA clause without any regard to the boundaries of the allotments.

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

The BCA does not require fire doors to be provided to the openings between united buildings if the floor area limitations of 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 when assessing the united buildings then the openings may need to be protected by fire doors and the subject walls considered to be fire walls under the BCA.

Where united buildings involve different classes, the requirement for separation of these in accordance with C2.8 and C2.9 of the BCA 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 under the Building Code of Australia.

Building owners and designers should consult with the building surveyor before applying for a building approval, building permit or construction certificate to ensure that both parties are aware of the full implications of the BCA on the united buildings.

Building Legislation Table

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