Glue-down Installation Guide

Glue-down installations are messy compared to other installation types and have the highest rate of failure if not done properly. The glue-down flooring installation method, if done properly, can result in a very sturdily-bonded floor.

Typically the glue-down method is used with engineered or parquet wood floors over concrete subfloors. If your only choice is a glue-down installation, please consult a flooring professional to ensure you have all necessary tools and preparation for your project.

The glue-down installation method is somewhat complicated and there are several important steps to follow:

1. Remove any dirt, debris, or surface irregularities from the work area

   This can include paint, wax, oil, plaster, "sheetrock mud" and other foreign materials. You may choose to sweep or vacuum the entire work area thoroughly. Remove all previous or existing glue or adhesives on the floor before installing new hardwood flooring.

2. Ensure that your subfloor is flat

   It is crucial to have a flat subfloor when proceeding with a glue-down installation. Use a level and determine and areas that will need to be sanded or ground down or will require a filler to raise low areas. Always consult a professional before making any adjustments to your subfloor to ensure structural integrity will not be ruined.

3. Ensure that the work area, building interior, and subfloor are dry

   The interior walls should be dry enough to be painted. Ensure that the area has a room temperature as required by adhesive manufacturer with a relative humidity of 30-50%. Check different areas of the room for moisture before beginning installation. If excessive moisture is present, do NOT install flooring.

4. Check the moisture level

   As a general rule, wood or plywood and concrete subfloors should not exceed 12% moisture content or a 4% moisture content difference between wood flooring and subfloor, although it is recommended to acclimate your floors to be within 2% of the moisture content of the subfloor to be safe.

5. Snap chalk lines to keep floor properly aligned

   You will want to snap a minimum of two (2) chalk lines for alignment purposes. These lines should be roughly 18" from the starter and ending walls of your floor. Account for a 3/8" expansion gap and 3 - 5 rows of flooring when measuring out your chalk line from the starting wall. This line will serve as your starting point for the installation. Dry fit the rows of flooring to go from your starting chalk line to the wall to ensure that the proper expansion gap remains before laying any adhesive. During the dry fitting, measure and cut plank to ensure each row is staggered and leaves proper expansion room against the walls. It is a good idea to snap additional chalk lines roughly every 10 rows worth of flooring to ensure that your flooring remains aligned well. At a very minimum, snap an ending chalk line roughly 7 - 10 rows before the ending wall, this line should be parallel with your starting line. Some installers will choose to begin their floor from the wall itself, but it is safe to begin installation from the line if you want to ensure that the floor remains straight.

6. Begin installation

   Beginning at your starting line, begin troweling adhesive evenly over the area from your starting line to the wall. Ensure that you are using the manufacturer’s suggested adhesive and trowel size, typically a 1/8" square-notched trowel is used for wood floors with a urethane or similar adhesive. It is crucial to ensure that the adhesive is spread evenly and that you do not use too much adhesive.

   Lay your first rows of flooring, ensuring to stagger each row, begin either at the wall or the chalk line. As you put each plank in place, try to prevent the adhesive from getting into the tongue and groove area, as this can cause the planks to be tougher to fit together snugly. Once you have installed the first few rows between the chalk line and the starting wall, use some painters tape, laid diagonally over the flooring every 12" or so, to keep the flooring in place and prevent movement while the adhesive cures. If needed, use a pull bar before laying tape to ensure the planks against the wall are snugly fit into the second row. You may need to use a rubber mallet to tap the final row along your chalk line into place firmly. If any adhesive happens to come up through the grooves to the surface of the flooring, keep a rag and some mineral spirits on hand and wipe them up promptly to prevent any damage to your floor’s finish.

   It is suggested to let this starting area fully cure over night before installing the remaining flooring in the room. These rows, once cured, will serve as an anchor for the rest of your flooring and will help to keep the floor straight. You may need to use a roller in order to ensure that the floor is properly seated into the adhesive. Check your floor manufacturer’s suggestions for the weight and frequency of rolling. For glued cork floors, it is common to need a 100 lbs. roller every hour for 4 - 6 hours and some hardwood floors have similar requirements.

7. Continue installation

   Once the starting area has fully cured, you can resume laying out additional rows. Remember to keep a rag and mineral spirits on hand to wipe up any excess glue which comes up through the seams in your floor. Also, remember to use painter’s tape every after every few rows, laid in diagonal patterns to help hold the new planks in place. It is suggested to trowel out enough adhesive to lay 5 - 7 rows of flooring, depending on plank width, at a time. Do not lay too much adhesive at a time as it could become tricky to lay planks without disturbing the adhesive.

   Once the floor has been completely installed, try to prevent any foot traffic, beyond any necessary rolling, from going over the floor while the adhesive cures. Typically adhesive will cure over night, but consult the adhesive manufacturer’s instructions for cure times. Once the adhesive has cured, you can then remove all of the painters tape. Spot clean any additional adhesive which may have come up and if any marks have occurred on your floor, use a color matched flooring putty to fill gouges.

8. Wet-lay vs. tack installs

   An important note about two subtle differences in glue-down installations: some manufacturers will suggest a specific method of tack vs wet-lay. The wet lay method is fairly common; this method involves laying the planks of flooring directly into the adhesive after it is troweled out while it is still wet. Some floors are not approved for this based on the type of adhesive used, typically those which cure via evaporation rather than via a chemical catalyst, these floors require allowing the adhesive get to a tacky consistency. This consistency can typically be touched by hand and strands of glue will pull away with your hand, somewhat like taffy being pulled. The wet-lay method tends to be a bit faster to install, but make sure which method is suggested by your floor’s manufacturer.

9. Post installation

   After you have given the adhesive time to cure and removed any tape and glue from the floor, you can then install all of your trims and transitions. It is a good idea to give the floor a few days before moving any furniture, especially heavy furniture. This will ensure that the floor is fully settled, as there is a short period after the adhesive has cured over night where the floor is going through a settling stage. Typically after 72 hours you can move furniture into the room.