Why do wooden floors develop gaps?
Wooden floors commonly develop gaps because wood naturally expands and contracts as its moisture content changes. Seasonal changes in humidity, dry indoor air, installation conditions, and the type of flooring can all affect how much the boards move.
Seasonal changes in humidity
Wood absorbs and releases moisture from the surrounding air. During humid periods, wooden boards can absorb moisture and expand. When the air becomes drier, they lose moisture and contract.
As individual boards shrink, small spaces can appear between them. This is particularly noticeable during dry weather or when indoor heating keeps the air relatively dry.
The wood was too wet or too dry when installed
Wood flooring needs to be properly conditioned to the environment before installation. If boards are installed before reaching an appropriate moisture balance with the room, they may change size significantly afterward.
For example, flooring installed while unusually moist may shrink as it dries, creating gaps between boards.
Indoor heating and low humidity
Heating systems can make indoor air considerably drier during colder weather. As the moisture content of wooden flooring decreases, the boards can contract.
Small seasonal gaps may therefore appear during dry periods and become less noticeable when humidity rises again.
Installation problems
Poor installation can contribute to excessive or persistent gaps. Problems may include:
- Inadequate acclimation of the flooring
- Incorrect fastening
- Insufficient expansion allowances
- Installing over an unsuitable or uneven subfloor
- Using inappropriate installation methods for the type of flooring
The correct requirements depend on the specific flooring product and construction of the building.
The type of wood matters
Different wood species and flooring products respond differently to changes in moisture. Solid wood generally has more potential for dimensional movement than some engineered flooring products because of its construction.
The width and orientation of individual boards can also affect how noticeable movement becomes.
When are gaps normal?
Small gaps that appear during a dry season and become smaller when conditions become more humid can be a normal consequence of wood movement.
However, large, permanent, rapidly increasing, or uneven gaps may indicate an installation, moisture, subfloor, or structural issue that deserves closer inspection.
How can gaps be reduced?
Keeping indoor conditions reasonably stable can help reduce excessive movement. Avoid exposing wooden floors to unnecessary moisture, clean spills promptly, and maintain the flooring according to the manufacturer's recommendations.
If gaps are significant, do not immediately fill them without identifying the cause. Filling a floor that is still moving seasonally can result in the repair cracking or failing later.
For substantial or persistent gaps, a flooring professional can determine whether the problem is primarily seasonal movement, installation-related, or connected to moisture or the subfloor.
In many cases, some seasonal movement is simply part of owning a wooden floor. The important distinction is between normal changes that follow indoor humidity and gaps that indicate an underlying problem.
