Movement Joints - The Right One For the Job (Part Two)

The reason there are so many different systems available, is to ensure there is a joint which is suitable for every conceivable individual application.

Most tilers know movement joints must be installed in certain areas and positions to prevent tiles or grout from cracking, and in some cases, the tiles tenting and becoming debonded from the substrate. But certain features make a particular joint absolutely right for one application, and wrong for another. 

Some joints which are designed and engineered specifically for residential, offices, or light commercial use just wouldn't be able to cope with the mechanical stresses of heavy duty applications such as airport terminals and railway stations, for instance. For those sort of uses, you would need a much stronger profile which is also capable of withstanding greater degrees of shear stresses. 

Here, we look at a selection of movement joints covering a wide variety of different applications. Figure 1 features an aluminium profile with a central movement zone. When installed, the visible profile is 6mm wide, which corresponds to the width of the average grout joint. This type of profile is suitable for commercial and heavy duty applications.

Many joints come in a variety of metal anchoring legs, as shown in Figure 2 - either aluminium, brass or stainless steel -- connected to a replaceable rubber movement zone. It's this zone which actually absorbs the movement, and can be replaced in the future if it becomes worn or damaged, without having to remove either the tiles or the profile.

Each material is suited to different types of applications - whether a heavy duty or lighter duty profile is required all depends on how strong the joint needs to be. And, of course, that depends on what is being asked of it...namely, it has to respond to the expected mechanical or chemical stresses that the tiled surface will be exposed to. 

Aluminium is suitable for areas like shopping malls, supermarkets and offices. Brass can be used in the same areas, but is much more resistant to high mechanical loads such as vehicular traffic, or those found in production facilities and railway stations. 

While stainless steel can also be used in all applications it is particularly suited in areas which may be exposed to chemicals - places like laboratories, chemical production facilities and leisure centres.

And for areas where the stresses aren't expected to be as forceful, Figure 3 shows a one-part PVC profile, with a visible surface width of 10 mm. These PVC profiles can be safely used for tiled surfaces both indoors and out. They're ideal for residential or light commercial use in offices, retail stores, shopping areas which aren't exposed to metal wheeled traffic, and car showrooms.

And for coping with structural expansion...Figure 4 shows a structural expansion joint profile which can be made of aluminium or brass with lateral joint connections to a sliding telescopic centre section. This allows the absorption of three-dimensional movement.