Allow me to elaborate a bit. As a general rule, water and wood don’t mix. However, that doesn't mean all of the time. I revert back to the statement at the beginning of this column. Technology is changing everything. With the advancements in production of engineered floors, water based adhesives are becoming more acceptable. But even water has its limitations. Think about it, if you were installing a very thin engineered floor, i.e. 1/4" or 5/16" would you want to use a water-based adhesive that had a large concentration of water in its chemical composition? Of course not; the moisture migration from the adhesive to the back of the wood flooring and the absorption would be much greater because of the thinner layers. However, if you were to use a water-based adhesive on a 9/16" or 1/2" product it would be much more difficult for the floor to cup due to the thicker layers. Water/latex/acrylic adhesives are generally a little less money and are environmentally friendlier. However, when used in the wrong installations become disastrous.
Thickness of the wood to be installed
Dimensions of the trowel
Subfloor thickness and composition
Moisture test -- Calcium Chloride.
There are many alternatives to water based adhesives and I will explore and few of these and give some of the advantages and disadvantages to each.
Moisture Cured Urethanes: These are some of the most common adhesives on the market today. The advantages are that it has no water, has shear strength, and good tensile strength. As long as the subfloor isn’t wet, this is all you need. Disadvantages are: doesn’t spread very easily; as a moisture-cured product, Relative Humidity will play a major role on curing and open time; and it contains isocyanates and sensitization can occur after prolonged use. Isocyanates also damage the surface of pre-finished flooring if left on the surface too long. They are very difficult to clean up.
Solvent-Based Adhesives: These left the market about 10 years ago, but there are some newer technologies in this category too. Advantages: Performance is unmatched; Quick grab (green grab); it spreads easily; and cleans up easily off of boards and installers. The disadvantages are that it has an odor (solvent), and it’s flammable. Some will argue this is perhaps the best adhesive available.
MS Polymers and many other types of adhesives are on the cutting edge of technology in the adhesive world. Advantages are: easily spreads; easily cleans up; and no VOCs, isocyanates or water. These adhesives are fantastic in composition and are environmentally friendly. They are almost safe enough to eat.
The only disadvantage to them is that they do not adhere well to closed-cell surfaces, such as marble or sheet vinyl.
As you look for adhesives, always consider the following and don’t concentrate on the cost of adhesive. After all, Shouldn’t you pass that on to the customer?
1. Species and Dimensions of wood.
2. Determine how susceptible to moisture that flooring is.
3. Check the sub floor and do your prep work.
4. If a moisture barrier is needed, pick a system and not just any moisture barrier with any adhesive.
5. USE THE MANUFACTURER’S RECCOMMENDED TROWEL. IT’S A MEASURING DEVICE TOO!
If you look at all of the above and think of how a job may turn out, take away the guess work! Don’t skimp on adhesive. After all, it’s what differs a good job from a bad one and ultimately its what distinguishes you as a good installer from a bad one.