Hardwood Flooring Adhesives

Generally speaking, only engineered hardwood floors can be glued down. There is currently much debate on this topic within the industry, as most hardwood manufacturers will not warrant solid hardwood floors that have been glued down, however there are certain adhesive manufacturers that spec their adhesive for the installation of solid wood floors.

Adhesive can be applied to the following substrates for the installation of wood floors – concrete, ceramic tile, terrazzo, slate and marble, masonite, acoustic cork, wood subfloors, fully adhered vinyl sheet and resilient tiles. Wood flooring can be glued directly to concrete, however not over a concrete sealer or painted concrete, and if present must be removed by sanding and grinding.

Not all concrete mixtures are suitable for the application of adhesive. Acoustic concrete may contain large amounts of gypsum or other acoustic material and can inhibit the adhesive bond. Test the concrete by scraping with a nail or sharp object and if the concrete powders then it is probably not suitable for the application of adhesive.

There are many types of adhesives available to the consumer, from water based to cross linked resin and urethane. 333333333333 Urethane adhesive is not affected by exposure to moisture or water and offers the most superior adhesion qualities. Urethane adhesives are moisture cured, and once cured their superior elastomeric properties provide a tough, flexible, tenacious bond to a variety of surfaces. The elastomeric characteristics allow the adhesive to move with wood as it expands and contracts.

Storage:
Store in a cool dry place and out of direct sunlight. Upon delivery, inspect seal on adhesive container to ensure that it is intact, as if seal is not intact it is possible that air has spoilt the adhesive. Note that once the seal on a urethane adhesive container has been broken and air has been allowed to enter, the curing process starts and cannot be reversed and it is therefore necessary to utilize the adhesive within a short period of time or it will become unusable. The curing process can be slowed by placing a piece of polyethylene film on the surface, in contact with the unused portion of the adhesive and then replacing the lid making sure the container is tightly sealed.

Drying times:
Adhesive drying times vary from 45 to 90 minutes and the container must be kept closed between drying times in order to prevent thickening. Only spread sufficient amount of adhesive that can be covered within specified drying times (see side of container for specified drying times). These drying times will vary according to humidity, subfloor porosity and room temperature.

Adhesive Application:
Clean trowel frequently to avoid adhesive build up. Always use the recommended trowel to spread adhesive and do not allow heavy film to form on the adhesive. Should this occur, remove the old adhesive and spread fresh adhesive. Avoid foot traffic for 24 hours after installation and do not apply finishes to unfinished products until adhesive is properly cured. Also do not cover floor with non-breathable materials.

Subfloor Preparation:
All concrete slabs must be completely cured and dried. Subfloors must be flat to within 1/8" in 6 feet or 3/16" in 10 feet. If low spots exist, fill them with Portland cement based leveling compound. Subfloors must be free of all foreign substances as well as concrete admixtures, grease, paint, dirt and alkali salts. Any loose subfloor material must be renailed or properly bonded to create a sound subfloor, and always do a moisture test when installing over a concrete subfloor.

When selecting an adhesive, always ensure that it contains no chlorinated solvents or ozone depleting chemicals and complies with all current state and federal regulations for Volatile Organic Compounds.