Hardwood Floors April/May 2026

By Chad Bulen

“Callbacks come from shortcuts” is a phrase my grandfather engrained in me growing up in the wood flooring world. Callbacks are the “anti-profit” aspect of a business and, unfortunately, create a bad image for our industry.” Chad Bulen of Bostik

Once the adhesive is cured, the removal process can be more challenging, often requiring razor blades, wipes, and solvent adhesive removers. Adhesive technology/chemistry has evolved over the decades with “easy clean” products being more available. HOLLOW SPOTS Contributing factors may include: • Subfloor preparation • Trowel selection • Adhesive selection • Warped or bowed flooring Hollow spots commonly are created by one (or all) of the four items listed above. Subfloor “flatness” is by far the number one situation we see when inspecting hollow spots. The perfect recipe for hollow spots involves an uneven substrate, a trowel or application practice that creates short adhesive ridges, an adhesive that slumps after being troweled out, and warped/bowed flooring. The solution is to fix the low spots with surface preparation products like skimcoats, patches, or self-leveling underlayments. Choose a trowel that promotes tall ridges and achieves proper transfer of the adhesive to the back of the flooring. Purchase an adhesive that has a feature set for ridge retention and stands tall once applied. Lastly, remove any bowed or warped flooring when racking out the floor.

ADHESIVE NOT BONDING Contributing factors may include: • Contaminants on a substrate • Quality of the substrate (old friable gypsum/cement or burnished/polished concrete) Over the years, I have seen numerous complaints of “adhesives not bonding” to a substrate and upon visiting the jobsite, I discovered the substrate has paint overspray, drywall dust, or old carpet adhesive residues. Contaminants properly need to be removed down to a clean and porous substrate. If they are not removed, the adhesive cannot bond to the substrate – because it’s bonding to a contaminant.

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the magazine of the national wood flooring association

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