By Charlie Nielsen, Technical services manager, W.F. Taylor
For many years non-porous carpets have typically been installed with the use of pressure-sensitive adhesives. This method allowed the adhesive to totally dry to a tacky state before installation. These products were mostly heavy 6-foot-wide vinyl back goods or were cut into carpet tile.

The latest technology has allowed manufacturers to create non-porous carpets without the heavy backings needed to seal moisture out from penetrating the backing material. The challenge has become installing these products over non-porous surfaces using conventional wet set adhesives where there is no avenue for moisture to escape through either of the surfaces. So how do you ensure a successful installation over a non-porous substrate?

Testing for porosity: Place a drop of water the equivalent to the size of a nickel on the concrete floor. If the water beads up and is still visible after 30 seconds the floor is considered non-porous. If it soaks in to the surface it is considered porous.

Porosity effects on adhesive: Any adhesive that contains water will require the water be removed for it to cure. The primary way this occurs is through the use of open time once the adhesive has been spread on the floor. The secondary way moisture escapes is through absorption into the substrate surface. The more porous the substrate the quicker the adhesive will cure.

Trowel size: Most non-porous broadlooms have a fairly smooth backing and require less adhesive to bond to the floor. A 3/32 x 3/32 x 3/32 V Notch trowel is recommended. The use of this trowel will provide a greater exposed surface area for the adhesive to “flash” quicker compared to U and Square notched trowels.

Bond test: New concrete: Should be cured, clean, level and dry. It should be free of curing or parting agents, any chemicals or other contaminates that interfere with the bonding of the adhesive. A simple bond test using the recommended trowel and adhesive along with the specified product will help determine if bonding problems exist.

Primers: If a sealed substrate is too smooth it can become difficult for the adhesive to bond to the surface. To enhance the bond the use of a primer applied to the floor will effectively de-gloss the surface and provide a more suitable surface for the adhesive to bond.

Summary

1. Perform a bond test ahead of time.

2. If the floor is slick and the bond test fails apply an approved primer.

3. Use a 3/32 x 3/32 x 3/32 V notch trowel. (Using too much adhesive can cause bond failures.)

4. Allow the adhesive enough open time until the adhesive when touched will create legs up to 2 inches long. Use fans if necessary.

5. Drop the carpet into the “flashed” adhesive and roll immediately with no heavier than a 75-pound roller.

6. Keep heavy rolling traffic off the floor for 48 hours.

7. Maintain HVAC systems. Airflow will speed adhesive cure strength.