Having a Leaking Balcony? Here is Why Balconies Leak

Leaking Balcony, Balcony, Chair in Balcony

With the vertical development of our communities over the last few decades by the advent of hi-rise apartment living we are able to enjoy the great out doors from our balconies. Balconies for many are a new type of construction paradigm, both for the builder and for the owner. They are an external element of the building but must be properly integrated to work with the internal elements of the building. Balconies are usually constructed above apartments, offices, retail & general living areas and are effectively a shallow sloped/low pitched roof to these areas at the ground level and therefore, it is critical that balconies have appropriate drainage and isolation from the internal elements of the building.

Find the cause and cheapest repair method for your leaking balcony. Let forensic experts at MFS Engineering investigate and determine the root cause.

Most probable causes of balcony failure in Melbourne

Balconies in Melbourne are either timber frames or reinforced concrete. Leaks in timber balconies cause the structural timber members to rot while in concrete balconies it can cause concrete spalling compromising the structural integrity of the balcony. Based on our experience we have noticed that the leaking balconies have lately become the second largest building issues within Melbourne (after tree root desiccation effects on footings).

Here is what we have found the most probable causes of balcony failure in Melbourne:


Inadequate surface fall

Inadequate falls of the surface causing ponding water – Note that according to AS4654.2 “Waterproofing membranes for external above-ground use” balcony, falls are required to be no flatter than 1 in 100.

Waterproofing failure

Waterproofing membrane failure can happen due to inadequate installation or it can be damaged as a result of long term wear and tear deterioration / failure. Damage to a waterproofing membrane can easily occur not only during the installation but as a result of thermal changes in temperature or long term building movements.

cracked balcony, crack in balcony, balcony, crack
Inadequate surface drainage

such as eaves gutter or waste outlets, to the balconies causing the surface water to drain away from the balcony surface at the edges. This lack of the drainage provision would also cause the constant water ingress into the timber members located at the edges of the timber framed balconies.

Incorrect tile installation

The tiles should be installed with correct movement joints to be able to expand and contract during cyclic temperature changes. It is imperative that expansion joints are installed where the balcony floor abuts the vertical wall. This is particularly important for large balconies; expansion joints need to break up the field and allow the tiles to expand and contract. Insufficient expansion joints within tiles cause the tiles to crack and water to leak into substrates damaging the waterproofing membrane.

leaking balcony

Learn more about how forensic structural engineers can help you Here.

If you have a leaking balcony it is crucial to find out why as soon as possible before the structure is undermined. The sooner the problem is diagnosed, and the cause is found the cheaper the repairs might be. Contact forensic experts at MFS Engineering for help.

Effect of Trees on Footings (Simplified)

Melbourne Geology (Simplified)


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