Balconies, decks and balustrades

Homeowners, tenants and property owners should regularly check and maintain any balconies, decks and balustrades. If not properly built and maintained, they have the potential to be a serious safety risk.

Building or replacing a balcony or deck

If you want to replace or build a new balcony or deck, you must ensure it is designed and constructed legally. That usually means:

Appoint a registered builder to do the work, if the cost of the project (including labour and materials) is over $10,000. A structural engineer can ensure the design of the balcony or deck meets building codes and requirements. They will make sure that if the balcony or deck is fixed to a building, the building can support the structural loads.

Part of the design will include allowances for the maximum number of people likely to use the balcony and maximum weight of features like large pot plants or furniture.

Risk factors for balconies, decks and balustrades

There are many things that can affect the structural safety of a balcony, deck or balustrading, such as:

  • Loadings – groups of people and heavy items (e.g. large pots, water features) provide additional loads for a balcony to support. The balcony may not have been designed to support so much extra weight. If overloaded, it may collapse.
  • Termites – for timber balconies and decks in areas of termite risk, the appropriate timber and treatment are needed. This is regardless of whether the council has declared the area likely to be subject to termite attack.
  • Wet rot – occurs when timber is in constant contact with the ground or in the presence of moisture.
  • Seaside and corrosive effects – unprotected steel structures, reinforcing steel and fixings (e.g. bolts and fixing plates) can be corroded (rusted), particularly in coastal areas.

The correct design and maintenance of decks and balconies should take these issues into account.

Most well-maintained timber balconies should last for at least 20 years, and a well-maintained concrete balcony should last for 40 to 50 years.

Safety measures for owners

All homeowners and commercial property owners with balconies, decks and balustrades should regularly inspect them for signs of damage or deterioration. You should do a visual check each year using the guides below.

If you are worried about the stability of a balcony, deck or balustrade, avoid the area and restrict access. Contact a structural engineer or other suitably qualified building practitioner, who will be able to inspect and determine the full scale of the problem.

Checking timber balconies

All exterior timbers are susceptible to insect attack and decay. A properly applied stain or paint finish will reduce water entry, but moisture can easily penetrate gaps and joints.

Your annual check should include the following:

  • Check the structure is properly fixed to the building or that the beams run into the building.
  • Check the base of timber posts for rot and check brackets and bolts for signs of rust.
  • Ensure that water does not pond at the base of a post or at a wall support, or pools on the balcony surface.

Check handrails and balustrades to make sure they are not rotted, corroded, loose or unstable.

Certain timbers, such as Oregon or untreated pine, are more susceptible to external environments. You may need to check balconies made with these timbers more often.

Checking concrete balconies

All concrete balconies are susceptible to decay, but it might not be easy to see. Cracking and flaking concrete and corrosion of reinforcement are signs of decay. Small cracks in a concrete surface may look harmless but allow moisture to get in, which can cause problems.

Your annual check should include the following:

  • Check if the balcony is level. If it leans, there is a problem.
  • Examine the underside of the balcony. Rust stains on exposed steel reinforcing are signs of a serious problem.
  • Check handrails and balustrades to make sure they are not rotted, corroded, loose or unstable.
  • Look for spalling (where chunks of concrete are flaking off or cracking). This may indicate there is a serious problem that needs to be inspected by a structural engineer or suitably qualified person familiar with concrete structures.

Checking balustrades

Balustrades or handrails are often made of concrete, steel and timber. They need to comply with building regulations and standards in terms of height, tension and fixings.


  • Balustrades must be at least one metre high, measured from the adjacent finished floor surface. Check the height of your balustrade, particularly if tiles or some other paving may have been applied after the balustrade was installed.

Tensioned wire

For balustrades using tensioned wire, it’s essential the size and tension of the cable meet the building code. Steel or wood should be solid to properly support tensioning.

  • Check to see if the wire seems loose.
  • Also check the distance between cables and any other supports that form the balustrade.

Toughened glass

  • When toughened glass panels are used, it’s important to regularly check that it is safely attached to the balustrade structure.
  • Any cracked or broken glass panes should be immediately replaced.


  • Make sure that fixings, such as metal stirrups to floors, bolts and screws are tight. Loose fixings on balustrades or handrails are unsafe and can result in injury.

Horizontal climbable elements

  • Where it is possible to fall more than 4 metres, check that any horizontal elements of the barrier between 150 mm and 760 mm do not facilitate climbing.


  • Check that there are no openings in the barriers that can permit a 125 mm sphere to pass through the barrier.


  • Balustrades or handrails using steel rails or posts can be susceptible to rust or corrosion. By painting steel with an anti-rust coating and inspecting them regularly you may avoid unsafe rust occurring.
  • Timber balustrades are more susceptible to the elements than other materials. This is particularly the case in coastal areas where the combination of salt and rain can be damaging. Make sure you use an appropriate weather-proof stain or paint.