Building safe balconies and decks

Friday, 6 February 2015

When designing or building a new balcony or deck, there are several things practitioners must take into account to ensure the safety of the structure. 

Before starting work on the project, practitioners should talk to the homeowners to understand how they intend to use the deck or balcony and whether they plan on placing heavy items such as pot plants, barbecues, large tables and furniture on the structure. This extra weight may require the size of the footings, supporting members or fixings to be increased.

Designers, engineers and building surveyors should pay particular attention to:

  • the method of attachment
  • the types of fixings that are being used
  • ensuring the timber or steel is of adequate size and suitable for use in external environments.

Where the deck or balcony is close to the sea or other corrosive environments, practitioners must use galvanised or stainless steel fixings, rather than plain steel, to prevent corrosion.

Balconies and decks should be waterproofed to prevent water ingress to the supporting structure and to ensure compliance with Australian Standard AS 4654 – Waterproofing membranes for external above ground use. It is also important to provide a slight fall on a deck or balcony to reduce the ponding of water that may cause timber members to become weathered and decay.


A well thought-out design and construction method will help reduce the risk of the deck or balcony collapsing. However, homeowners still need to carry out regular maintenance and check the balcony or deck for any signs of deterioration.

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