Crack Isolation Techniques
The junctions between floors and walls, between neighboring walls, and between tiles and other materials are where structural or thermal movement is concentrated, and thus the need for movement joints. Movement joints are also required in any tilework installed directly over existing movement joints, or wherever the tiles are installed over two different substrates. Movement joints are essential whenever the plane of tiles is interrupted by pipes, conduit, or other penetrations; the lack of movement joints can make replacing or repairing plumbing valves and the like extremely difficult.
Movement joints, unlike tile and other tile installation materials, will wear out and need periodic replacement. This should be considered with any warrantee you might provide your customer. Maintenance of the movement joints is important to the longevity of the tile installation, especially if the installation is in a wet area.
Sometimes, if there are movement problems with a substrate, or if waterproofing is required, a membrane system may be required for a successful tile installation (Photo 1). Membrane systems may be comprised of a factory-made sheet that is adhered to the substrate, or liquid/fabric combinations. Membrane systems are available for waterproofing, crack isolation, and for sound reduction. Without exception, all membrane systems require that movement joints be included in their installation to ensure reliable results, and this is especially true for crack or movement isolation membrane systems that must also insulate the edges of the tile installation from normal and expected movement within the structure.
The tiles were hand-made, shaped like leaves, were to be inset into a maple strip floor. The challenge was to enclose the relatively stable tiles with the highly moveable wood strip floors. Installing hard grout between the tiles and the wood strips would result in an unsightly crack. This installation called for an elaborate movement joint that would add to the installation, but which would require extensive reworking of the existing wood strip flooring, the substrate, and the structure.
The final step was to install the sealant, and the result was an award-winning floor that, after two years, looks as good as the day it was finished (Photos 4 and 5).