Solid hardwood floors must be fixed into position by either gluing or nailing down to the subfloor. Engineered hardwood floors can be glued or nailed into position, but they also have the option of being floated over an underlay.
The recommended glue for floating installation is Tongue and Groove engineered flooring glue. Glue placement is very important. The glue must be placed along the topside of the groove the full length of the grooved side and end.
Adding glue in addition to staples or cleats creates more holding power across the full width of each board to fasten the wide plank floor to the subfloor.
If your room(s) have a concrete subfloor, gluing the floor down will be your best option. This will allow a large continuous installation with few transition pieces. In very dry or humid regions, gluing the floor down will limit expansion and contraction of the floor.
Glued down engineered wood flooring is the most popular method of installation, and we always recommend this options because it's the more stable option out of the two.
Many wood flooring manufacturers opt not to provide glue-assist guidelines at all. Further contributing to potentially confusing or absent instructions from manufacturers is the fact that glue-assist is not a requirement, but simply an optional aid for flooring installation.
The most popular type of wood flooring glue is urethane glue. This floor adhesive is in a solid form and won't evaporate in the air. This flooring adhesive forms a solid rubber structure between the surface and top of the subfloor.
Apply a 1/4 –inch continuous line (bead) of construction adhesive such as LIQUID NAILS® Subfloor and Deck Construction Adhesive (LN-902) along joists before laying your chosen flooring. When laying hard floors, you will need to apply the adhesive as you work across the floor, one board at a time.
No, 3/4 solid Hardwood flooring can expand and contract more than engineered wood flooring. I would not suggest direct gluing down any 3/4-inch thick solid Hardwood flooring to any surface, the adhesive bond might not allow the solid wood flooring to move or breath normally and can cause the wood flooring to distort.
Place shims or spacers in the gap between the flooring and the walls to hold it firmly in place. Holding the finish nailer at an angle, shoot nails through the tongue every 8 to 10 inches. Install the next piece of flooring against the chalk line, aligning the tongue and groove between the two pieces.
Glue-down floors are seen as a more permanent fixing method, and is preferred when you expect the flooring to stay there for decades. Wood that has been glued down allows for the necessary expansion and contraction, without risking too much growing or shrinking which could lead to cracks and more serious damages.
The most common way to lay hardwood flooring is by aligning the planks parallel to the longest wall. Apart from a few exceptions like sagging joists, this is the preferred direction to lay wood floors because it aesthetically provides the best result.
Since the planks are pieces of real wood, they are affected by changes in moisture levels. Hardwood floors naturally expand and contract as the relative humidity fluctuates from one season to another. That is why installers must leave space between each wood plank and the wall; this allows the wood to “breathe”.
These days, the standard width in hardwood flooring is the 4- or 5-inch wide plank. Curious minds may know that the standard has grown wider with time. These widths are often the go-to because the boards can fit nicely and effectively in most rooms.
Winner: liquid nails
As we've said, liquid nails are formulated for construction. So, naturally, it has stronger bonding properties than wood glue. As long as you follow the application instructions properly especially the drying time, you'll get unbeatable bonding results.
Wood glue strength ranges from roughly 3,600 to 4,000 psi—that is they can withstand pressures of between 3,600 and 4,000 pounds per square inch. The adhesive bonds of wood glues—as well as epoxies and polyurethane adhesives, both of which can also be used to join wood—are stronger than most woods.
Most urethane flooring adhesives will fully cure 12-20 hours after they're laid, depending on the humidity levels of the environment in which they're installed. It's generally advised that glued down floors will accept light traffic in 12-15 hours and heavy furniture 24 hours.
To calculate the amount of adhesive to purchase, simply multiply the values supplied by the number of square feet of flooring you are going to install. For example: 6” planks require 240 lineal feet of adhesive per 100 square feet of flooring to be installed. If your job is 500 square feet, multiply 5 x 240 ln. ft.
Polyurethane based glue
Polyurethane based products are the adhesive of choice for installing wooden floors, but they work well with vinyl too. They use a substance called isocyanate dissolved in a solvent. This type of glue usually has low levels of VOCs, making it suitable for large scale applications like floors.
Gluing hardwood floors includes pros like giving your floors a solid feel and sound as well as being least likely to have deflection between flooring and subflooring over nailing hardwood floors. One added bonus to this is you should not hear squeaking.
OSB can accommodate glue-down, nail/staple or floating hardwood installations. With glue-down, follow the hardwood flooring manufacturer's guidelines. Some prohibit water-based adhesives given the potential for both the flooring and wood substrate to absorb moisture from the glue.
Things You'll Need
Many people don't bother to glue down their plywood underlayment. Instead, they just screw or nail the boards to the subfloor. This is fine if you're not worried about the long-term durability of your work.
Moisture in Spring and Summer
Fall is a perfect season for hardwood flooring installation because the cool, crisp weather exposes your hardwood flooring to less moisture.