Why Adhesive Application for Tiles is Important
TANZ gets asked when tiles are installed is it ok to Spot, Dot. Dab fix the tiles?, some don't even know what that is. In this article we will discuss why adhesive application for tiles is important.
A bathroom that is tiled provides both a durable and refined finish that is difficult to compare to. The keys to the bathroom finish performing is reliant on good waterproof membrane application and correct tile installation, as the tiles provide a protective layer over the membrane and when correctly installed the bathroom will perform for many years with trouble free performance. The performance of a tiled shower is expected to last at lest 15 years but often much longer, with tiled showers exceeding 30-40 years.
For the tiled shower to reach and exceed the New Zealand Building Code requirements for Durability (B2) the tile installation must follow the requirements of the standard AS3958.1.
This standard is referenced in many cases on the tile adhesive product instructions, technical data sheets and also referenced in the BRANZ appraisals for the membranes, which is relied upon by the Building Consent Authority.
What Does AS3958.1 Require?
One of the main requirements for tile installation in the standard AS3958.1 is "how" the adhesive is applied to the substrate and tile. The standard AS3958.1 indicates that the adhesive is to be applied by means of a suitable sized notch trowel and that the adhesive is to provide adequate coverage between the tile and surface area. In most cases the adhesive coverage for tiles installed in a shower is between 85-100% coverage.
The Risk of Spot, Dot and Dab Fixing
So what occurs when the adhesive is not applied correctly? Unfortunately we see the method of "spot fixing", dot fixing" or dab fixing used to install wall tiles in showers and bathrooms. This method results in limited coverage of tile adhesive to support and adhere the tiles to the substrate/membrane.
This limited support means the grout is more likely to crack and allow moisture to accumulate behind the tiles, in where the membrane can become damaged and then allow water to enter the building elements.
AS3958.1 states the following. Spot-fixing' where the tiles are fixed with four or five dabs of adhesive is not recommended and should be avoided at all times. Care should be taken to ensure that, as far as possible , no voids are left behind the tiles.
Spot fixing (dab/dot fixing) creates voids where water can accumulate and then affects the performance of the tile installation and the bathroom. This in turn will impact on the performance of the shower to meet E3 (Internal Moisture) of the NZBC, especially E3.3.6 where it states, Surfaces of building elements likely to be splashed must be constructed in a way that prevents water splash from penetrating behind linings or into concealed spaces.
When the water from a shower is allowed to accumulate behind the tiles and sit in the voids created by spot fixing the membrane can become compromised
It is always recommended to apply the adhesive as per the manufacturers requirements and in line with the standards and best practice requirements, which will limit any voids and provide full support for the tiles which helps prevent the grout from cracking, increasing the performance of the shower for years to come.
Want to know more? Contact TANZ