Why is Subfloor Preparation So Important?

Why is Subfloor Preparation So Important?

Subfloor preparation is crucial because it provides a solid, level base for the installation of new flooring materials. Without proper preparation, the subfloor may be uneven or cracked, which can cause the flooring to shift, buckle, or wear unevenly. This can not only be unsightly, but also unsafe, as it may create tripping hazards or compromise the structural integrity of the flooring.

A homeowner in Stuart, FL recently contacted us and stated that the new flooring installed by [company name redacted] produces a crackling sound throughout their home, but that it was worse in the entryway, where they explained they heard crunching and snapping sounds when walking in that area.

When a flooring store comes to your home to measure, most do their best to evaluate the condition of the subfloor. The fact is, you can?t really know until the old flooring is removed. We see this vital step omitted by other flooring stores quite often. If your flooring store isn?t talking to you about a level subfloor, they are committing malpractice.

We sent one of our installers to check it out. He could feel the deflection of the flooring with each step. In the entryway, each step felt different; one step was hard, and the next step, it felt spongy. When he stepped on the flooring in the entrance area, the plank adjacent to the wall sunk down causing a visible gap between flooring and the baseboard. The plank adjacent to the wall tilted downward toward the wall, making a gap under the baseboard.

The other two areas, where the dips were found, showed excessive vertical movement in the flooring when he walked across the room. He measured the deflection to get an idea of the flooring flatness. He found two areas exceeded the manufacturer?s tolerance. These are the areas that made the crackling sounds.

The installer removed several 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.



Investing time and effort into proper subfloor preparation can help ensure a long-lasting, safe, and attractive flooring installation.


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. 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.

Uneven subfloors are a common issue. We have heard from installers that some homeowners do not want to pay for getting the subfloor to within the flatness tolerances of the floor they are installing, 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. Omitting this vital step can often mean having to purchase new flooring, twice.