How to Fix a Leaking Balcony

Understanding and Addressing the Consequences of Leaking Balconies

If it has a balcony, it will leak 

This is unfortunate statement quoted from an article: "Melbourne’s high-rise nightmares taking a tall toll on residents and investors" The Age, Melbourne 25th September 2016
Though this article was referring to Melbourne’s booming construction in the multi level apartment sector, many capital cities across Australia are experiencing similar issues. And leaking balconies are not restricted to multi level apartments, but unfortunately to many recent constructions.

Effects of Leaking Balconies 

There are several key points within this article I would like to emphasize

  • Residential multi-story, multi-dwelling, apartment buildings are experiencing an alarming frequency of building defects, most commonly caused through waterproofing failure.
  • Balconies were identified as a major cause of waterproofing problems.
  • This has led to the common assumption that for many multi-level balconies “proper waterproofing membranes are not installed”.
  • The market has inconsistencies about Insurance cover, both from building trade cover and the residential owners cover. Resulting in the building owner necessitating to self-fund the corrections to the building.
  • The Victorian Government is making new laws to protect consumers whilst also recognising the ‘overwhelming majority of builders’ do the right thing.

"Efflorescence" occurs only in the presence of water.

Complete Strip Out - Leaking Balcony

This article diving into the question “Why is my balcony leaking” has been supplied by Paul Evans, Findlay & Evans Waterproofing – President of Australian Institute of Waterproofing (AIW).

Construction methods are always changing and adapting.

As a Registered Building Practitioner, I have noticed recently, either for reasons of design and/or cost considerations, changes in balcony construction methods which have a direct impact on the success or otherwise of the waterproofing membrane.

Waterproofing Leaking Balconies - Multi Level Apartment 

  • Many balconies are currently being constructed with minimal falls to the substrate; particularly evidenced in multi-level apartments.
  • This design has a significant effect on the choice of waterproofing product, installation method and tile adhesives used.
  • The balcony membrane must be capable of “standing water”; as a balcony with minimal fall will have water ingress through the grout resulting in moisture “ponding” between the membrane and tiles.

Best Waterproofing Product to Fix Leaking Balconies?

  •  Waterproofing membrane MUST be able to withstand "PONDING" water. 
  • If the waterproofing membrane selected cannot withstand ponding water – and many waterproofing products on the market cannot – over time and together with the normal cyclic thermal contraction and expansion of a building, this will cause the membrane material to break down and/or joint failure and cause water leaks.

Why do Balconies Leak ?

  • Balconies and walkways are exposed to the destructive forces of the elements: rain, wind, sunlight, and freezing conditions.
  • All too often, penetration of water is through the top balcony surface and exposed edges of both reinforced concrete  and timber framed balconies.
  • This leads to deterioration of the balcony structure and significant defects occur, such as concrete spalling.Accumulation of calcium crystals and salts is known as “Efflorescence”.
    Efflorescence only occurs on balcony surfaces due to the presence of water.

How to Fix a Leaking Balcony? 

In my experience, there are recurring issues causing waterproofing failure:

  • Inadequately waterproof detailing from balcony to wall interfaces.
  • Using cheap (inferior) waterproofing products to save money.
  • Railing post and penetrations causing water ingress due to poor preparation and detailing.
  • Poorly detailed balcony surface transitions, interfaces and penetrations can lead to water ingress into occupied spaces below which in turn may lead to serious structural damage. Failure to pick up building defects through the building surveyors’ inspection process.

Damage due to leaking balcony above.

Damage due to water leaks.

  • Unfortunately, many of these issues are not always taken into consideration when contractors/specifiers/designers are deciding on waterproofing products and methodology for constructing balconies.
  • This may result in the owners, investors and owners’ corporation having to face the challenges of solving future leaking balconies.

Best Balcony Waterproofing Product

  • A waterproof system should have comparable expansion capabilities as the balcony structure itself.
  • This means, the waterproofing material used to seal a balcony should be flexible.
  • Balcony water proof product needs to contract and expand with the normal thermal cycle.
  •  Adherence: the membrane should strongly adhere and seal to all horizontal & vertical surfaces i.e balcony surface, balustrades, penetrations & adjoining walls/structures.
  • Create a permanent and robust water tight bond & seal around all balcony edges, and interfaces.

Can balconies be repaired without removing tiles?

  • Re-grouting and surface sealing is not the way to repair a leaking balcony if it has been established there is a defective membrane.
  • This band-aid method may stop or slow down water leaks for a while. 
  • That is until the balcony moves and cracks the grout again and inevitably the balcony will start to leak all over again.
  • Unfortunately in most cases of leaking balconies to provide a long term solution is a complete strip off, re-install a new membrane, screed & tile or whatever other finished surface  i.e instant turf.

After numerous attempts at stopping water leaks, this balcony had to be stripped and membrane re-installed.

Waterproofing Method for Successful Balcony Restoration & Repairs

  • Using Correct Waterproof Product – selecting long life membranes that are also cost-effective and suitable for the balcony design and conditions.
  • Membrane must be capable of bridging cracks and joints within the sbalcony substrate.
  • Correct Waterproof System -  make water tight all balcony surfaces, interfaces, and penetrations.
  • Membrane Flexibility - the waterproof membrane must be able to move with the normal contraction & expansion of the balcony envelope.
  • Waterproof Membrane must be able to withstand “ponding” water.
  • Waterproof System installed with minimal disruption to building occupants.

Rooftop Balcony & Instant Turf

Balcony Waterproofing Company - Melbourne

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Findlay-Evans Waterproofing Company


Read Our Article  - First Published March 7, 2017

A waterproofing company that thinks CONSTRUCTION