Schlüter-Systems Movement Joint Series , Supporting Particularly Heavy Loads

In last month's technical advisory article, which concluded the seven-month series on the importance of using the correct movement joints in ceramic and stone floors, we looked at how an uncoupling system allows independent movement of the surface covering, from the substrate. This neutralises stress cracks or timber board joints, preventing reflective cracking in the surface.

Ian Knifton, Technical Manager at Schlüter-Systems, now looks at two other important aspects of that same system – waterproofing, and supporting particularly heavy loads.

Schlüter received the following query from a flooring contractor: "Schlüter®-DITRA, the uncoupling membrane described last month, sounds perfect for protecting the tiles in a leisure centre’s changing rooms and showers for which I’ve been given the flooring contract. But is it waterproof?"

And the answer is: Absolutely. In fact, the British Standards Institution (BSI) recommends using impervious membranes such as this system, for waterproofing, even if uncoupling is not required. The mat provides a waterproof membrane beneath the tile covering, making it ideal for internal applications such as bathrooms and shower rooms. The open air channels on the underside of the system allows moisture from the substrate to evaporate, meaning it is also entirely suitable for use over “green” screeds or concrete.

It can also be used for external applications, such as balconies. Moisture which is present in the adhesive bed in such external applications is not a problem even if it freezes. The membrane has the flexibility to accommodate the expansion of the ice, which simply evaporates after thawing.

The same contractor told us he was also due to tile a car showroom with extremely heavy-duty tiles, and he wanted to know if this uncoupling system would be able to support the weight of the cars.

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Columns or pillars can support tremendous loads when placed on a solid foundation. The same physical principle allows this mat-type uncoupling system to support heavy loads, since the cured tile adhesive forms column-like structures beneath the tile. For almost 20 years the Schlüter®-DITRA, system has proved itself to perform in a variety of applications subjected to high loads, including vehicular traffic.

It has been tested using the Robinson-Type test method, which covers the evaluation of ceramic floor tile installation systems. This test method is intended solely for evaluating complete ceramic floor tile installation systems for failure under loads and not for evaluating particular characteristics of ceramic tile, such as abrasion resistance. This test method does not claim to provide meaningful results for other than evaluating complete ceramic floor tile installation systems.

The major requirement of the system is that both the tiled surface covering and the substrate must be capable of supporting the intended loads. The calculation is the number of Kilo Newtons per metre squared (KN/m2).

While the strength and size of the tile will vary depending on the demands of each particular installation, the minimum requirement for this type of system is that the tiles should be at least 50 x 50 mm, and they must be solidly embedded into the tile adhesive. Back buttering of the tile may be necessary to achieve solid bedding.

For extra heavy-duty areas the membrane should be used over concrete/screed substrates with the required load bearing capacity and corresponding tile. The same criteria applies to point loading, in that the surface covering should have the correct point load capacity.

For more information, contact:

Stewart Bint
Telephone: 01530 813396
Fax: 01530 813376
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

Advice From Experts - Movement Joints