Unfortunately, failures of tile installations do occur. Although they are limited to less than 0.1% of all tiles installed, the cost of failure can be high and consequential damage significant. Whilst frequently blamed, the tile adhesive is seldom the cause of tile installation failure. It is more likely to be an installation issue.
Provided the reasons for failures are understood and due precautions are taken, installation failures need not occur. Past experience shows that the main causes of tile installation failure are one, or a combination, of the following:
differential movement not catered for in the tile installation
selection of inappropriate products for the service conditions
poor workmanship on site
Let’s briefly consider these in turn:
One of the most common causes of failure is the build-up of stresses due to the cumulative effect of differential dimensional changes to a point high enough to cause delamination along the weakest plane. This could occur between the tiles and fixative, within the fixative itself, or between the fixative and backing material.
The most important factors contributing to differential movement are:
irreversible moisture expansion of ceramic tiles
size changes of backing materials
creep movement of the structure
other structural movements
Differential movements are a fact of life. They can, and should, be limited through judicious choice of materials and careful design. The critical issue here is to cater to the movement in the system by providing tile panel movement joints at close enough centres and using an adhesive system with enough plasticity to accommodate it. It is also essential that all structural expansion joints in the background are extended through the tiles to the surface.
Selection of inappropriate products
It is essential that the correct products are used for the intended application. Choosing the incorrect type of tile for the service conditions can be disastrous. Careful consideration must be given to the expected performance of the tile in terms of traffic requirements, resistance to scratching and abrasion, physical strength and porosity, particularly in external or wet environments.
Similarly, the adhesive and grout system must allow for expected movement, vibration, chemical attack, etc.
Naturally, the backing substrates must be suitably designed and specified to accept a tiled finish, i.e., they must be of sufficient strength and of a quality and consistency suitable for tiling.
Unfortunately, poor workmanship is all too common in South Africa. There is no formal registration of properly trained tiling artisans in this country, unlike in parts of Europe. Some of the most common ills of shoddy site work are:
poorly prepared background surfaces
tiling onto green concrete, screeds or renders
contamination on the substrate or the backs of the tiles
incorrect application of adhesive
incorrect adhesive selection for the tile and service conditions
adulteration of the tile adhesive
butt-jointing tiles, or too-narrow joints for the particular tile chosen
lack of allowance for movement in the form of correctly constructed intermediate tile panel movement joints and perimeter joints
subjecting newly laid tiles to service conditions too early
grouting before the adhesive has cured
Using quality products in accordance with the manufacturer’s instructions, and ensuring the prescribed standard of workmanship is followed, will ensure a successful tile installation.