Gaps between floor boards can be unsightly, and frustrating.

With few exceptions, all wood floors should be tight at the time of installation. A quality installer should always ensure that boards are nailed or glued tightly together.

Exceptions where gaps are expected can include:

• Working with rustic or tavern grade flooring material
• Leaving room for expansion as required by the flooring product and environment
• Matching up to previously installed products.

The first thing to understand about gaps that develop after installation is they are always a result of a change in the floor’s moisture content.

Usually, the environment in which the floor is installed is drier than the floor itself. Wood adapts to match its dry environment by losing moisture and shrinking in size. Gaps are the most visually apparent result of this process. There are two kinds of gaps:

Seasonal gaps

All wood floors can be expected to experience seasonal gaps due to changes in temperature and relative humidity. When conditions get dry, wood will tend to shrink causing gaps to appear between boards.

The National Wood Flooring Association (NWFA) defines normal, seasonal gaps as: “gaps that appear between individual boards and open and close with changes in humidity”¹.

Acclimation to the average living conditions of the home, and maintaining your home at those conditions (usually between 35-55% relative humidity) will keep your wood floors in the optimal environment to minimize shrinking or expanding. A whole home humidifier is a great way to help maintain a consistent environment in your home.

Abnormal gaps

Gaps that are not normal are defined by the NWFA as “gaps in the floor that remain with seasonal change”².

Abnormal gaps may be the result of an installation error, not acclimating the floor properly prior to installation, or severely dry conditions that have caused the boards to gap excessively.

Are gaps covered by manufacturer’s warranties?

Seasonal gaps are considered normal and temporary and are not covered by a manufacturer’s warranty.

Most abnormal gaps are the result of an installation error, poor job site conditions, poor acclimation, or severely dry environmental conditions. These are all examples of things that a flooring manufacturer cannot control, and are not covered by warranty.

1,2 “Problems, Causes, and Cures of Hardwood Floors.” 2nd Edition. National Wood Flooring Association Technical Publication No. C200. 2011. www.nwfa.org