Written with contributions from Brendon Manson, Founder of TANZ, the Tile Association of NZ.
The two areas in any home that are often the talking point are the kitchen and the bathrooms. This is where the most money per square metre is invested and there is no doubt that a tiled bathroom presents the “wow factor”. If poorly done however it can be a nightmare from hell.
Recently, an MBIE regulatory reform consultation document noted:
Poor waterproofing often results in failures, leaks and costly repairs which would be lessened greatly by better regulation in the area…Waterproofing is a minor part of overall construction costs, but accounts for the vast majority of building defect complaints and huge costs in remedial works. Many building leaks stem from bathrooms and wet areas that are not properly waterproofed, which can affect the flooring and wall linings leading to mould, mildew, and rot. The build-up of moisture and mould can cause health hazards such as fungal infections, allergies, and respiratory illness including asthma.
Research from TANZ (Tile Association of New Zealand) suggests that the tiling/waterproofing failure rate in New Zealand is more than 1 out of every 10 installations. Since its founding in 2017 TANZ has counted over $300,000,000 in failures, with 89% of these failures being attributed to the installer.
Unfortunately, these issues may not manifest themselves for months or even years and often the builder is left carrying the can when they do. This is because legally and contractually you are responsible for the services supplied to your customer, who justifiably will expect you to make it right. However, because tiling is a highly fragmented industry it can be difficult to pin down the responsible contractor when the problem arises. This could be because they have shut up shop, simply disappeared or weren’t properly insured in the first place (and insurance is becoming harder to obtain for these issues).
Despite tile installers being responsible for 90% of all membranes applied within a bathroom the tile industry’s focus has not always been about education and training for installers. If the tiler is not correctly trained or the installer does not fully comprehend the importance of all aspects of the application of the membrane and the associated details then the result can be failure.
In the past, training has been basic and has often been provided by product manufacturers who have focused on product sales, rather than best practice requirements, with some manufacturers providing as little as 30-minute product demonstrations before issuing an “approved applicator/licence card”. While others have provided more extensive training programs, the result of poorly trained tilers is failed, leaky showers even by approved applicators of membranes.
Although water-stops have been a requirement of AS3740 (Waterproofing of Domestic Wet Areas) since 1989, TANZ identified the lack of water-stops as a contributing factor in almost all the failed tiled showers it has assessed.
TANZ is working to address the issues outlined above and provide the solutions, so that the sector can be part of the Licensed Building Practitioners regime and installers of membranes and tiles can be properly trained and licensed.
TANZ have recently produced an updated Best Practice Guide for the industry (visit www.tanz.net.nz to purchase a hard copy or TANZ members can download it for free).
The insurance perspective
Time and again we are approached by builders needing to make liability claims for leaky bathrooms. Sometimes this is to do with plumbing connections but more often than not it is due to defective waterproofing and/or tiling installation. These claims are not straightforward and often take time to unravel who is responsible for the damage and whose insurance should be covering it in the first instance. There are complex issues around legal vs contractual liability and the assessment process can take time, not to mention the affect on the builder’s claim history (and future premiums) as a result of errors by a subbie. It’s also not unusual to find out that the tiler isn’t answering their phone anymore!
How can builders safeguard their projects and clients from risk?
1. Ensure the substrate is ready and accessible to the tiler. Time pressure and an inadequately prepared surface often contribute to membrane failure.
2. Engage properly trained installers. Training doesn’t come from “just spending years” in the industry. Just because someone has being doing a job for 20 years doesn’t mean they’ve been doing it correctly. You should require that your tilers have undertaken TANZ’s T.E.A.M training programme. Visit www.tanz.net.nz for a list of upcoming courses in your area.
3. Ensure all wet areas are built to meet E3/AS2 requirements as per the IWAM Code of Practice, with the use of water-stops and wall cavity protectors to contain moisture within the shower area.
These simple steps will greatly reduce the risk of possible waterproofing failures and the associated stress, conflict and cost. The ‘wow factor” of a beautiful, tiled bathroom is trouble free and only adds value to the home when it is done correctly the first time.