Buckling: Adhesive failure when a floor is under compression. Possible causes are subfloor movement (shrinkage) or flooring growth. When floors are installed in hot, humid weather, the underlayment boards are swelled with moisture. The application of adhesive over the boards puts additional moisture into the boards. With the winter heating season, humidity within the area is greatly decreased due to the heating of the building. As the moisture evaporates from the boards, the boards shrink. The best prevention of this type of problem is installing in a controlled climate. There is no way to repair buckles in felt-backed sheet flooring other than to replace the floor.
Ridges and Tunnels: Ridges are small, tunnel-like raised areas, over underlayment joints; approximately 1/4″ wide. Tunnels are longer ridges. Usually as a result of an installation made during the winter heating season when humidity is low and in some cases, underlayment will be dried out before installed. If underlayment boards are installed in dried-out condition, they will grow when the water-based adhesive is applied as a result of absorbing the moisture. Since the flooring is bonded to the boards, and the boards are growing, the only way for the material to relieve itself is to buckle over the joint. Depending on the type of product, this buckle can vary from a slight mount to a very sharp ridge or pucker, or it can shear itself loose and create a tunnel over the joint. These tunnels can be sheared loose on one or both sides of the underlayment joint. The only way to correct this problem is to reinstall. However, it can be prevented by conditioning on site, installing ahead of time, priming joints.