Photo Credit: Sean Gillies on Flickr. Licensed under Flickr Creative Commons

Squeaky floors are a dreaded callback that most contractors face at some point. And most of the time, you’ll find that the root cause is actually not the floor itself, but the subfloor. Unfortunately, if the subflooring itself is squeaky, it usually will have to be replaced.

But before you start ripping up the subfloor, you must identify the root cause of the squeaks in order to properly address the problem.

Some causes of squeaky subfloors include:

Water damage: Moisture is the worst enemy of wood, and the same holds true for subfloors as well. According to Jason Elquest of Blackhawk Floors, “[If a floor] experiences water damage at some point in its life and is not properly repaired, then there is a good chance squeaks will occur. We see this in floors that have been refinished after a flood or water leak.” So be extra careful if you’re dealing with a subfloor that’s been subjected to water damage. Inspect it carefully to determine whether the extent of the water damage warrants replacement.

Solid wood subflooring: This type of subfloor can cause squeaks. If you’re working with a solid wood subfloor, make sure it’s made of a dense softwood such as fir and that it does not exceed 6” in width. Also make sure the subfloor is installed on a 45-degree angle, with all board ends full bearing on the joists.

Cutting costs: With new home construction, the joists can also pose a problem, especially in terms of joist spacing. Since floor joists are expensive, builders will sometimes push the limits on spacing to save on costs. In this case, you will have to reinstall the joists and properly fit the subfloor over them in order to fix the issue.

Quality matters: Some commodity-grade panels can allow deflection up to the thickness of a quarter between the framing. This kind of vertical movement can create squeaks, creaks, and pops in flooring systems.

Maybe it’s not the subfloor – check the humidity

Sometimes the problem is not the subfloor but rather has something to do with the floor itself and how it’s reacting to changes in humidity.

A very common cause of squeaky floors is wintertime contraction and the release of moisture from the wood. You can tell if this is the case by taking moisture measurements of the flooring.

If the flooring is within the normal humidity range for its species but it’s simply reacting to the humidity drops, you must help the homeowner understand that this is simply a natural process. Provided the flooring was installed correctly, the planks should expand back to their proper size once the weather turns warmer and the relative humidity increases.

You can read more about how to fix a squeaky hardwood floor here.