Current at: 24 January 2011
Evading efflorescence in tiling (Nat)
One of the most common member enquiries we receive in the Building Services
section nationally relates to problems with tiled balconies and the occurrence
Efflorescence (as commonly described in the construction industry) is the
formation of calcium carbonate on an external surface, in this instance on the
exposed face of the tile. Most commonly, the formation of efflorescence is
caused by water leaking through cement mixtures and dissolving calcium
hydroxide. On contact with the atmosphere the calcium hydroxide reacts with
carbon dioxide to form calcium carbonate. In most instances the efflorescence
forms around the grout lines.
A more serious problem is leaching. This is where there is serious water
leakage in the tiling system and a more extensive build up of calcium carbonate
occurs, again around the grout lines and edges of the balcony. Quite commonly
where there is a drop from the balcony edge stalactites can form as seen in the
Is It a Defect That the Contractor is Responsible For?
Yes and no. Minimal efflorescence is not a contractor’s responsibility to fix
outside of the 6 month minor maintenance period and should be looked after by
the homeowner. AS 3958.1-2007 Ceramic Tiles Part 1: Guide to the Installation
of Ceramic Tiles includes efflorescence in the cleaning and maintenance
appendix and indicates that mild efflorescence can be removed with a cleaning
solution containing phosphoric acid.
Where there is extensive efflorescence or leaching has occurred it most
likely means that there is a bigger problem than just white residue appearing on
the tiled surface. In most cases it means that the waterproofing and drainage
system of the tiled bed has failed and is allowing water to leach through the
cement bed and not drain away sufficiently. The formation of calcium carbonate
is normally the first sign there is a problem. While this is an aesthetic issue
it should be used as a signal that water is not being sufficiently drained away
from the balcony. If nothing is done further down the track more serious damage
can occur such as drummy tiles and complete failure of the waterproofing system.
In buildings where the balcony is over a habitable room failure of the
waterproofing system can be quite detrimental. In these instances the contractor
will be held liable for rectification within the structural warranty period,
because waterproofing the structure is a principle Performance Provision of the
Can Efflorescence Be Avoided?
Most tiling and waterproofing experts will say no, efflorescence cannot be
avoided completely, however it can be minimised and serious damage prevented.
The priority is to limit the entry of water into the cement component of the
tiling system and then control the exit of any water that does get in.
Chemical fixes such as sealers can assist but they are not as effective as
physical measures. For rectification work, a chemical fix will most likely be
the preferred option to save time and money.
Physical measures and good design are the most effective means of avoiding
efflorescence and leaching. To reduce the entry of water a positive fall on the
balcony away from the building to stop ponding of water is the most obvious
measure however this is sometimes not enough.
Systems such as a double waterproof membrane or applying a sealer to the
tiles and grout will assist. To control the exit of water an adequate drainage
system is essential. For example, draining the water to a floor waste will help,
though this is not always the most desired installation aesthetically. Another
option is to install drainage outlets at the edge of a balcony, such as a
spitter (overflow pipe), that will direct the exit of water and allow it to run
through the cement bed rather than dam up and leach through grout lines or
Probably the other most important factor when trying to avoid efflorescence
or leaching is simply ensuring a quality of workmanship is met. Making sure that
the coverage of adhesive to the tile is at least 90%, use the right sized trowel
for the job and ensuring that the adhesive is compatible to the surface which it
is being affixed (your supplier will be able to advise you about this). These
processes will increase the adhesion of the whole system which will result in
less movement and less water penetrating and potentially building up underneath
HIA would like to thank the following people who assisted in the preparation
of this fact sheet:
- Bryan Vadas, TimeMasters
- Andrew Golle’, Armont Rectification Builders & Consulting
- Presentation by Colin Cass on Efflorescence at the Full Frontal Tile &
Stone Expo in Sydney, August 2009
For further information HIA members can contact HIA’s Building Services
staff on 1300 650 620 or firstname.lastname@example.org.
If you would like to become a HIA member, contact 1300 650 620 or mailto:email@example.com
Disclaimer: The above is intended to provide general information in summary
form. The contents do not constitute specific advice and should not be relied
upon as such. Formal specific advice should be sought by members with respect to
particular matters before taking action.