Renovation in "The Big House"
By Peter Nielsen
As published in Tile Design and Installation
Ceramic tile is the ideal flooring surface for institutional kitchens and bakeries. It provides a sanitary working surface and, in addition, adds durability, function, and permanent quality where alternate flooring surfaces can’t compare. Because the performance of a properly installed ceramic tile installation is dependent upon the dimensional stability of the substrate, installing tile in the kitchen and bakery facilities of Retreat SCI (State Correctional Institute) presented its own set of unique challenges.
The surface covering in the kitchen and bakery complex at Retreat SCI was poured terrazzo over a suspended concrete slab. The area was subjected to heavy institutional traffic and considerable static loads from large commercial appliances. The floor did not have sufficient allowances for control joints, and cracks in the terrazzo had developed throughout the facility. Over time, the floor had become pitted and gouged, creating a trip hazard and making it undesirable from a sanitation point of view. In an earlier attempt to rehabilitate the floor, it was painted with an epoxy paint which, in turn, created a difficult surface to bond to. Further, it was apparent that effective waterproofing had not been provided as evidenced by the water damage in the room below.
Several options were considered before reaching a permanent solution. The first option was to install a reinforced mortar bed on top of a cleavage membrane. This would prevent movement in the substrate from telescoping through to the tile surface. However, this method was rejected because of the additional weight and height it would add to the finished installation. Installing the tile using a trowel-applied elastomeric membrane was also considered. This method provides a primary waterproofing layer, is light weight, and does not add additional height to the finished installation. However, trowelable membranes do not distribute load or allow for movement as effectively as other systems. Also, they do not allow for realignment of the control joints. In addition, uncured elastomeric membranes produce toxic fumes and cause skin irritation on contact.
After studying the different options, it was determined that all of the objectives could be met using the Schluter-DITRA matting. DITRA has opened new windows of opportunity and allows tiling over problematic substrates that have traditionally challenged the industry.. The roll applied matting "detaches" the finished tiled floor from the substrate. and also bridges cracks, and absorbs movement. The 1/4" thick matting eliminates the need for a second sheet of plywood or cementitious backerboard. DITRA acts as a waterproofing membrane when the DIRO seaming tape is used to seal the seams and the KERDI 25 is used to seal the floor/wall connections.
John Box, the tile contractor for the project, was reluctant about using the system: "having never used the product before, we were apprehensive at first about using it, but our fears were soon proven to be unfounded". The DITRA matting would neutralize any movement in the substrate and support the surface covering under load. "The product is light in weight, easy to manage and install, and with its mechanical bonding surface structure, there is no concern for tiles not adhering to its surface. After working with DITRA, we agree to it proves not only to be an excellent waterproof system, but also an impressive anti-fracture membrane that can be utilized over weak or unsound substrates." said Box.
DITRA would eliminate the need for saw-cut expansion joints in the existing floor and permit the realignment of the control joints. In addition, it is chemical resistant and would add minimal height and weight to the finished floor. For movement control, the Schluter-DILEX-KS pre-made expansion joint was chosen. This would provide edge protection for the tile and eliminate the need for edge preparation. The DILEX-KS would provide the additional benefit of being virtually maintenance free and could be installed at the same time as the tile. Using Schluter-DITRA with the Schluter-DILEX expansion joint is the perfect installation method for ceramic tile in institutional settings and provides the ideal balance between function and durability. Asked whether he would use the system again, Box replied: "Should the need arise for a waterproofing/anti-fracture membrane in the future, we would highly recommend the use of the DITRA system".