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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.

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 to waterproofing.

Balconies leak due to design

The design has a significant effect on the 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 the membrane.

The inadequate number of expansion joints within the tile field. This will cause an uplift of tiles and the tearing of the membrane below.

Inadequate drainage for the size of the balcony

And there is the added failure of the 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 a constant run-off.

* Waterproofing installation maybe problematic if the 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..

Credit goes to The Paul Evans -Avatar


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