Installing Divider Strips in Terrazzo or Other Decorative Flooring
Divider strips are placed in epoxy terrazzo and other decorative seamless flooring systems in three places. The first is to create a design or change in color. The second is at termination points. The third is at joints in the concrete that will be referenced through the terrazzo system. While the first two areas are simply used to define terminations or aesthetic designs, the use of strips at joints can be a problem if not installed correctly.
True expansion joints or column isolation joints are expected to expand and contract over the life of the building. For this reason they must be referenced through the flooring system. This is accomplished by placing L-strips on each side of the joint and filling the gap between the strips with the appropriate soft material to handle the expected movement across the joint. The strip must be placed so that the vertical edge of the strip is over sound concrete. If the base of the L-strip extends over the joint, the strip may not support weight when loads move a cross the joint. In this case, an excess load will "tip" the strip into the joint, resulting in crack in the epoxy terrazzo at the far end of the base.
In some cases, the expansion joint will be wider than what is desired for the finished flooring pattern. If there is little movement expected due to thermal changes, this joint may be filled with a semi-flexible epoxy or polyurea material. A saw cut is made through the cured epoxy or polyurea material to allow for some movement and the strips are placed over the new fill material as described previously. This should only be done with the approval of the architect after the calculation of the anticipated movement.
Saw cuts or control joints can be filled, band-aided with the flexible membrane extending six inches on either side of the joint and the seamless floor is placed without the use of a strip. However, if the architect wants a "belt and suspenders" approach, the saw cut is filled with a semi-rigid epoxy, band-aided with a flexible membrane and then a single strip placed over the joint. The semi-rigid epoxy would support the strip and the membrane will handle minor movements.
In all cases where divider strips are used, correctly anchoring the strips to the substrate is critical to preventing future problems. Strips are the weakest point in the terrazzo or other decorative flooring system. The appropriate method is to apply an epoxy adhesive to the bottom of the strip prior to placing on the level substrate. Gaps below the strip will result in weak bond and will allow resin to migrate under the divider. If a construction adhesive is to be used to tack the strip into place, pour catalyzed epoxy onto the strip to encapsulate the strip to the concrete. Do not depend on the excess resin from the terrazzo to secure the strip.
Attention to these details during the installation of divider strips can prevent future problems and save on costly repairs. For more information on terrazzo and decorative flooring installation feel free to contact us at firstname.lastname@example.org.