The “Best Job Practices” column in the May/June 2000 issue of FCI magazine took the position that open time for adhesive installations is controlled by the time of year, the temperature, and the humidity level. In addition, the column implied that the installer who followed the information found on most product labels was not assured of a good bond during extremely hot or cold weather.
Those thoughts bothered me when I re-read them, so I went through my files of competitive literature, notes taken at industry meetings, and archived copies of articles on floor covering installation.
As I suspected, I found nothing addressing the subject directly. I then turned to my files on ceramic tiles installation, and uncovered some information that looks to be extremely helpful for installation professionals.
Hot weather is defined as “any combination of high air temperature, low relative humidity and, if outside or in a building with open windows, wind velocity.”
The National Tile Contractors Association reference manual states that “for organic adhesives, hot weather produces a creamier texture, increased workability, and a tendency to trowel too large an area before applying tile (author’s note: read that as carpet or resilient flooring). Hot weather causes rapid skinning and loss of open time due to the increased evaporation of water. The durability of the installation is compromised by the potential for poor transfer of adhesive to the back of the material to be installed.”
The NTCA manual also advises installers to “keep all materials in a shaded area, and do not store materials in closed trucks or vans. This includes adhesives, powder products, mixing liquids, and the materials to be installed. If any material is warm to the touch it is suspect. Cool your materials before proceeding.”
Additionally, in a Tile & Decorative Surfaces article by George Lavenberg published in July 1991, the author states that “most construction work is at the mercy of the temperature. When it is cold, the setting of powder products, mastics, etc…is slow; nothing seems to set up when we want it to. In hot weather the opposite is true; everything sets or films over quickly.”
There is one document in the carpet trade that addresses temperature and humidity. CRI 104/105 takes the position that “carpet shall be installed when the temperature is between 65 F and 95 F and the relative humidity is between 10% and 65%, and, if installing over concrete, the slab temperature should not be less than 65 F.”
For the contractor who knows that an installation is going to be done in hot weather, planning ahead can make the difference between success and failure. I would propose that the contractor associations in the floor covering industry put together a document along the lines of the NTCA reference manual, which is most easily described as a problem-solving guide for ceramic installations. It covers problem after problem, listing causes, preventions, and suggested corrections. It took years to put the manual together, but today it is seen as the bible of the ceramic installation industry, as well as an invaluable teaching aid to help prevent installation problems before they can occur.