Water ingress has become a major problem within the construction sector, leaking balconies is one of the main culprits.

Water leaks may cause not only aesthetic & superficial damage to the balcony surface itself but can also affect the structural integrity of the balcony building envelope.

A high-profile tragedy in California USA June 16, 2015, unfortunately highlighted the importance of maintaining the structural integrity of balconies. Six students died following the collapse of a fifth-floor balcony where they were standing. Several others were injured.

The California State Licensing Board subsequently ruled the collapse resulted from shoddy material selection and poor waterproofing workmanship, which had enabled dry rot and decay to embed in within the balcony timber joists.

Fixing water ingress due to leaking balconies can be time consuming, involve expensive legal battles, extensive and costly rectification works and exhaustive efforts tracking down elusive developers, builders, contractors and product manufacturers.

There is no doubt the old maxim “Getting it Right the First Time” should be the waterproofing mantra.


In my experience, there are several recurring issues seen over and over causing balconies to leak.

And not always due waterproofing.

Balconies leak due to design 

Design has a significant effect on management of water on a balcony.

  • A recurring design fault is inadequate falls built into the substrate.
  • Window/ door frame installation without the required 40mm turnup of membrane.
  • Inadequate number of expansion joints within tile field. This will cause uplift of tiles and tearing of membrane below.
  • Inadequate drainage for size of balcony

And there is the added failure of building surveyor’s inspection process not identifying these defects.

Lack of waterproofing contractor expertise

In the case of balcony construction, the standard of a waterproofer or waterproofing company’s workmanship and suitability of membrane selected is often hidden under tiles or a finished surface – sight unseen.

Unfortunately, the first indication of substandard membrane installation or unsuitable product selection, are water leaks.

This can occur immediately, probably the easiest water leak problem to fix, to several years down the track.

Correct balcony waterproofing best practice should include, but not exclusive to:

  • Substrate preparation, clean and dry. Critical to best practice methodology.
  • Detailing prior to waterproof application, includes all balcony penetrations, perimeter upturns, drainage outlets etc and must be meticulously detailed by hand.
  • Appropriate membrane selection – balcony membranes need to be flexible as are required to move with the normal expansion and contraction of the balcony structure.
  • Balcony membranes must be able to withstand “ponding water” i.e standing water. A tiled balcony will have moisture, at times, sitting between the membrane and tile. Some membranes cannot last without constant run-off.
  • Waterproofing installation maybe problematic if surface temperature is either too hot or too cold for some i.e. under 10C or over 35C. Rarely does construction scheduling take this into account.

Cost Cutting in Construction

The perennial issue within the construction sector – building for profit alone.

Cost-cutting on waterproofing during build is short sighted, and this critical element is so often not given serious consideration by the industry.

Unbelievably, waterproofing can be left out of construction estimation and costings, not even appear on drawings and plans, and then left out of build timeline scheduling.

Using cheap inferior and substandard products that are unsuitable for keeping balconies watertight, omitting best practice methodology like recommended primers, waterproofing applied over wet and/or dirty substrates, are just some of the measures used to claw back costs and time.

Waterproofing can be an item reduced to hurried afterthought taken onsite.

It is simply not good enough to have our buildings leak, with the consequences of resultant damage leading to lengthy legal battles, expensive and extensive remediation works, health risks and emotional turmoil for consumers.

What is the AIW doing?

AIW and MBAV Course: “Waterproof Training for the Construction Industry

The Co-Founded MBAV and AIW course, Waterproof Training for the Construction Industry, has been designed to educate personnel involved in the planning and designing stage of a project, and all industry professionals who have a responsibility to ensure a construction project is made watertight and shall perform correctly for a given period (min 10 years).

The continuing success of this training indicates, at long last, the construction industry is looking at waterproof design, planning and compliance and the contribution of waterproofing as a vital component in construct and build.

Waterproofing and Insurance Companies

The AIW is endeavouring to engage with Insurance Companies to provide information and knowledge, as Australia has a high percentage of insurance claims due to damage caused by waterproofing failure. These insurance claims often involve substantial payouts due to costly and extensive rectification works. The AIW would like to work with the insurance industry to formulate an insurance scheme for individual waterproofing project (over a certain $ limit).

Public Awareness

The AIW is currently taking an unprecedented amount of calls and emails from our members and the general public.

Although this is difficult to keep up with, it shows that public awareness is increasing, and answers are being sought.  Unfortunately, just about everyone knows someone within their family, work or circle of friends/acquaintances with a disaster “water” problem in a building.

By Paul Evans, President Australian Institute of Waterproofing and Managing Director, Findlay & Evans Waterproofing