A dark hardwood floor with gaps in them

Why do I have gaps in my hardwood floors?

One of our top 3 questions! You have gaps in your wood floors for a number of reasons, some of which you can control, some of which you can’t.

First, wood is hygroscopic meaning that it will absorb and release moisture, given the opportunity. In the summer when it is naturally more humid, the wood will swell and expand as it absorbs that moisture. In the winter, the wood floors will release the moisture and quite often shrink, due to the drier conditions. This type of expansion and contraction is considered normal and expected with wood floors, when exposed to seasonal variations. As this happens, many times throughout a wood floors life, the wood flooring can actually shrink permanently. Generally, this would be over a 50+ year time frame.

Sometimes, the gaps are caused by an improper floor installation, where the installer did not draw the boards close enough, when nailing them down, or using the wrong nails/cleats, or not enough nails/cleats.

Another cause is the wood was too wet at the time of installation, as the wood dried out, then the gaps became more apparent.

Some less expensive flooring has lower quality milling, creating bows and mis-matched end joints, which will also create some gaps.

Another cause can be subfloor issues where the subfloor is holding excessive moisture, or it has settled over time. Improper subfloor material (like particle board) that is not recommended by the NWFA (National Wood Flooring Association) and will not hold nails properly from the installation of the wood floor, thus causing more gaps.

Movement of deflection in your subfloor can also cause the wood floor to move and create gaps.

CURES: Never try to repair a wood floor with moisture issues, until that issue is resolved, and the floor and subfloor have dried out!

For isolated gaps, a qualified flooring contractor can remove and replace the areas and custom mill new boards that will bridge those gaps. If it is an entire floor, sometimes a full floor replacement is necessary.

We can try to control these gaps by having a good HVAC system that also controls humidity (like an Aprilaire system). Controlling the temperature is also very important. In a perfect world, we want to the home’s temperature between 60-80 degrees and the relative humidity between 30-50%.

WHAT NOT TO DO: Fill those larger gaps with wood filler or wood putty. In our climate, it is only a matter of time before that will crack out become little rocks on your floor that will in turn scratch the surface of your wood floor, along with giving you an uneven look as the filler splits and cracks in between the floorboards.