When it comes to gluing parquet flooring directly to concrete, moisture is the enemy. Concrete needs to have less than three per cent moisture content to hold glue properly. Although it is very difficult for the average homeowner to gauge the exact moisture content of a concrete floor, there are simple ways to determine if concrete is dry enough to glue a parquet floor onto it. For example, never glue a parquet floor directly to a concrete slab that is less than 90 days old, as it will have too high of a moisture content. Also, if you want your flooring to look its best, only glue to a perfectly flat concrete surface.
Clear the concrete floor of all furniture or other items and vacuum thoroughly with a good shop vac. Do not damp mop.
Place a 37.5 by 37.5 cm (15 inch by 15 inch) sheet of clear polythene plastic on the concrete floor. Tape it down with moisture-proof tape. Leave the plastic on the concrete for two days, then carefully lift it up and look for moisture. If there is moisture on the plastic or if the floor underneath looks darker, then there is still too much moisture in your concrete. Use heat lamps and fans to dry the floor for several days, then give the floor the two-day plastic-sheet-test again to determine if your drying efforts worked.
Bring your parquet flooring into the room where it will be installed and allow it to acclimate for two days. This allows the parquet to reach the same temperature as the room.
Buy a non-water-based glue designed for parquet being laid on concrete. You can usually find this type of glue at your local hardware dealer or home-improvement centre.
Lay out your flooring so the pattern is the way you want it. Re-stack the pieces so you can return them to the floor in the same order. Cut flooring pieces with a table saw or band saw so that there is approximately a 1.2 cm (1/2 inch) gap between the flooring and any walls or pillars. This gap lets the flooring expand and contract with changing temperatures.
Brush or roll on a thin layer of water-free flooring adhesive to a parquet sheet. Put the sheet in place. Press down on the sheet with your hands, using your body's weight to make certain the sheet is in full contact with the glue. Repeat for remaining sheets.
Allow the flooring to dry for 24 hours before allowing heavy traffic.
Parquet flooring may need to be sealed after installation. Consult your manufacturer's recommendations.