The use of pedestal installation systems for porcelain and other ceramic tiles has increased in popularity. But there are drawbacks and risks associated with pedestal systems, particularly when porcelain is involved.
It is vital that appropriate tests are carried out on any porcelain tiles intended for installation with a pedestal system. Testing can direct attention to risks such as susceptibility to impact rupture; it can also highlight how these drawbacks could affect the performance of a tile in service on the pedestal system.
Pedestal systems are often used as an alternative to traditional mortar bedding techniques. Their increasing popularity can be attributed to the benefits they provide, such as reduced installation time (labour), easier access to services (cables, pipes, etc) and benefits to drainage.
The main tests recommended for porcelain intended for use on pedestals:
- Stone Initiatives method SI-CLCP – tests the concentrated static load capacity of the porcelain tiles while installed on a particular pedestal system.
- British Standard method BS EN 14158:2004 (modified) – tests the impact rupture energy of the material.
- Australian Standard AS ISO 10545.3:2020 – determines the water absorption capacity and density of the tile.
- Australian Standard AS ISO 10545.4:2020 – determines the modulus of rupture and breaking strength of the tile.
- Australian Standard AS 4586:2013 – determines and classifies the slip resistance of the surface of the tile.
Left: Example of the static load capacity test (SI-CLCP) for porcelain on pedestals; Right: Example of the modified impact rupture energy test for porcelain on pedestals.
How pedestal systems work
Using a pedestal system involves laying structural strength pavers over a pedestal support system, which raises the tiles or pavers off the existing surface. This creates a void between the paving and the membrane, encouraging constant air circulation and providing benefits such as water drainage. There are many different brands of pedestals available and there can be substantial differences in strength and quality. We recommend obtaining a test report from the manufacturer showing the compressive strength of the pedestal before purchase.
Example of a pedestal support system, which raises the tile off the existing surface and creates a void between the paving and the membrane.
The risks to be aware of
The main risk with the use of pedestal systems is the danger of a pedestrian falling through when a tile breaks. This involves the risk of subsequent injury due to the sharp edges produced by broken porcelain, or injury due to the fall height. In addition to the risk to pedestrians, there is also the expensive issue of replacing broken tiles, particularly if failure occurs frequently in a large tiled area.
Why can porcelain tiles fail?
A single porcelain tile can fail and rupture for a number of reasons, commonly including, but not limited to:
- point load on the surface exceeding the load capacity/strength of the tile (e.g. imparted by moving a piece of heavy furniture, force applied by pedestrian traffic)
- surface impact causing rupture (e.g. falling object, a hard object striking the tile)
Porcelain is particularly susceptible to impact rupture due to its brittle glass-like nature. It is also particularly susceptible to excessive point loads due to a general construction industry preference toward the use of relatively thin porcelain tiles (often 20mm thickness) because of their lower cost. This is why the two most useful test methods for porcelain on pedestals are SI-CLCP ‘Determining the static load capacity of porcelain installed on pedestals,’ and BS EN 14158:2004 ‘Determination of Rupture Energy.’
How to minimise the risks
Appropriate and thorough testing is the most important step in minimising the risks associated with the use of pedestal systems for porcelain tiles. By engaging a qualified laboratory to run tests such as those outlined above, you can understand: any weaknesses the tile may have, thickness requirements for use on a specific project, alternative systems that may minimise risk, and project-specific data useful for engineers. With the resulting data and insights, you can ensure that your porcelain tiles are fit for use on the intended pedestal system, in turn minimising tile breakage and avoiding injuries and expenses associated with such failures.
For more information visit our ceramic tile testing page here.
Find sample requirements and other testing details on our FAQs page.
Get in touch with our engineered products specialist for more information on testing porcelain products for use on pedestal systems.