A homeowner reported that their flooring produced crackling sounds throughout their home, but that it was worse in the entrance hallway where they explained they heard crunching and snapping sounds when walking in that area.
The job was a 630-square-foot, three-ply 14mm x 3.5” x RL maple engineered wood flooring, using a floating installation method over a concrete subfloor. The underlayment was a 2.8mm foam vapor retarder.
As I walked across the flooring, I could feel the deflection of the flooring underfoot. In the entrance, each footfall felt different; one step was hard, and the next step, it felt spongy. When I stepped on the flooring in the entrance area, the plank adjacent to the wall sunk down causing a visible gap between flooring and baseboard. The plank adjacent to the wall tilted downward toward the wall, making a 5mm gap under the baseboard.
The other two areas, where the dips were found, showed excessive vertical movement in the flooring when I walked across the room. I measured the deflection to get an idea of the flooring flatness. I found two areas exceeded the manufacturer’s tolerance. Using a straight edge and a taper gauge or cm ruler, I measured the dip in two areas and found one at 5.4mm per 48.75” span (~8/16” per 10lf span) and another at 2.55mm dip per 25.65” span (8/16” per 10 lf span). These are the areas that made the crackling sounds.
Useful tip from an inspector: It is very important to ensure the subfloor is flat to the manufacturer’s tolerances and to remove all debris off the subfloor prior to installing. You can use scrapers and/or grinders then vacuum up all loose debris. This includes any substances affixed to the subfloor like blobs of drywall mud or loose debris like dirt or screws, or in this case, thin set from removed ceramic tiles.
The installer removed some boards in the entrance area, which revealed some thin set was left on the concrete where they removed ceramic tile. There was no visible self-leveling compound used. This caused the subfloor to be very bumpy and created the soft spots when stepping on the flooring and, in turn, producing the snapping and crunching sounds. The installer said that he thought the planks should bridge over the thin set, and it should be okay. He did not expect some of the thin set to come loose, causing the crunching sounds.
It is very important to ensure the subfloor is flat to the manufacturer’s tolerances and to remove all debris off the subfloor prior to installing. You can use scrapers and/or grinders then vacuum up all loose debris. This includes any substances affixed to the subfloor like blobs of drywall mud or loose debris like dirt or screws, or in this case, thin set from removed ceramic tiles.
Debris creates pivot points and the wood flooring plank is not supported properly. Pivot points create a raised plank and allow the flooring to have excessive vertical movement on each side. This causes stresses within the plank and the surrounding planks and can tear or fracture the tongues and grooves. Consequently, the flooring needs to be replaced, and the subfloor repaired in that area. The installer should have checked the flatness of the area where the wood flooring was to be installed, and prepared the subfloor as necessary.
There is no easy fix for an uneven subfloor under a floating floor application. In this case, the planks were glued together at the tongue and groove and they cannot come apart. The installer will need to remove the flooring in all of the affected areas. Sadly, it cannot be removed without damaging the flooring. The subfloor must be exposed to get it to within flatness tolerances. Once the subfloor is prepared properly, then the new flooring can be reinstalled.
There is no easy fix for an uneven subfloor under a floating floor application. The subfloor must be exposed to level it out. Once the subfloor is prepared properly, then the new flooring can be reinstalled.
One other consideration to keep in mind is that when you purchase the new flooring for the repair, you need to make sure the flooring matches. Colors and sheens can vary slightly from batch to batch.
Uneven subfloors are a common issue. I have heard from installers that some homeowners do not want to pay for getting the subfloor to within flatness tolerances, which can get expensive so they continue the job without taking this critical step. Noisy floors mean excessive movement of the flooring. Floating systems, or any installation method, will perform only as well as the foundation it is laid on.
Sharlene LaCroix is an NWFA Certified Wood Flooring Inspector and customer service manager for Qualiwood Enterprises Inc. dba ETM Distribution in Burnaby, British Columbia, Canada. She may be reached at firstname.lastname@example.org.