Have you ever noticed gaps between your hardwood floor planks? Or maybe your floors have started to cup or buckle?
Hardwood floors expand and contract in response to changes in humidity and temperature, leading to various problems. But don’t worry! There are steps you can take to minimize the impact of expansion and contraction and keep your hardwood floors looking and performing their best.
In this article, I’ll explain what causes hardwood floors to expand and contract and provide you with tips on how to accommodate this movement.
How Much Do Wood Floors Expand and Contract?
Hardwood floors can expand and contract by up to 1/4 inch (0.64 cm) over a 10-foot (3.05 meters) span of width for every 1% change in moisture content.
For example, a 20-foot (6.10 meter) wide hardwood floor could expand or contract by up to 1/2 inch (1.27 cm). In areas with significant humidity variations, wood floors undergo noticeable dimensional changes.
You can use a moisture meter to estimate how much your hardwood floors will expand or contract based on the moisture content of the wood. The movement rate of wood is directly related to its moisture content. The higher the moisture content of the wood, the more it will expand and contract.
Why Does Hardwood Movement Occur?
Hardwood floors expand and contract due to a process called hygroscopic movement. Hygroscopic movement is the absorption and release of water vapor by wood, which causes the wood to swell and shrink.
Wood is a porous material, meaning it is full of tiny holes. When the air is humid, water vapor in the air enters the pores of the wood, causing the wood to swell. When the air is dry, water vapor leaves the pores of the wood, which induces the wood to shrink.
Hardwood also contains cellulose fibers, which are strong and flexible but are also hygroscopic, meaning they absorb moisture from the air.
Observable Signs of Hardwood Floor Expansion and Contraction
Signs of hardwood floor expansion and contraction are crucial to identify early to prevent potential damage. Here are some danger signs you need to keep an eye on:
- Gaps between planks: One of the most noticeable signs of hardwood floor expansion is the appearance of gaps between individual planks. These gaps are caused by the wood expanding and pushing against each other. The gaps may be small and barely noticeable at first, but they widen over time if the expansion is not addressed.
- Cupping and buckling of planks: Cupping occurs when the edges of the hardwood planks curl upwards, while buckling occurs when the planks themselves warp and bow upwards. Excess moisture causes the planks to swell and lose their shape.
- Crowned or warped planks: Crowning is a condition where the center of the hardwood plank is higher than the edges while warping is when the plank twists or bends out of shape.
- Squeaking or popping noises: Expansion and contraction of the floorboards may produce squeaking or popping noises. The noise is caused by rubbing or friction between the planks or between the planks and the subfloor.
Factors Influencing Hardwood Floor Movement
Several factors can influence the movement of hardwood floors, including wood species and grain direction, installation methods and subfloor condition, and humidity and temperature fluctuations.
Wood Species and Grain Direction
Different wood species have different moisture contents and densities, which can affect their tendency to expand and contract. For example, woods with high moisture contents, such as maple and birch, are more likely to expand and contract than woods with lower moisture contents, such as oak and walnut.
The direction of the wood grain also affects the movement of hardwood floors. Wood expands and contracts more across the grain than along the grain. The cellulose fibers that make up wood are stronger in the longitudinal direction than in the transverse direction.
Installation Methods and Subfloor Condition
The method of installing hardwood flooring and the condition of the subfloor also influence its movement. Improper installation, such as using incorrect fasteners or not allowing adequate expansion gaps, leads to excessive movement and potential damage to the floor.
The subfloor, the layer beneath the hardwood floor, provides support and stability. A damaged or uneven subfloor creates stress points and irregularities that can cause the hardwood floor to move unevenly.
Humidity and Temperature Fluctuations
Humidity and temperature fluctuations are the primary environmental factors that cause hardwood floors to expand and contract. Wood absorbs moisture from the air when humidity levels rise and releases moisture when humidity levels fall. The absorption and release of moisture cause the wood to swell and shrink, respectively.
Temperature changes also affect hardwood floor movement. When temperatures increase, the wood expands, and when temperatures decrease, the wood contracts. The rate of expansion and contraction is related to the amount of moisture in the wood. Wood with higher moisture content will expand and contract more than wood with lower moisture content.
How to Accommodate Expansion and Contraction of Hardwood Flooring?
There are a number of things you can do to accommodate the expansion and contraction of hardwood flooring:
- Leave an expansion gap around the perimeter of the room. This gap should be at least 1/4 inch (6.4 mm) wide to allow the floor to move freely. You can conceal it with baseboards, shoe molding, or quarter-round.
- Install the hardwood floor over a floating subfloor. A floating subfloor is not attached to the joists, which allows it to move independently of the floor. It minimizes the stress on the hardwood planks and reduces the risk of buckling and warping.
- Use a moisture barrier under the hardwood floor. A moisture barrier will prevent moisture from the subfloor from migrating into the hardwood planks, especially in humid climates.
- Acclimate the hardwood planks to the home’s environment before installation by storing the planks in the home for at least 72 hours before installation. Acclimation will allow the wood to absorb moisture from the air and reach an equilibrium with the home’s environment.
- Maintain a stable humidity level in the home. The ideal humidity level for hardwood floors is between 35% and 55%. Use a humidifier or dehumidifier to maintain the desired humidity level.
Frequently Asked Questions
Do Hardwood Floors Expand Lengthwise?
Yes, hardwood floors can expand lengthwise, but it is a relatively small amount, usually less than 1/4 inch per 10 feet.
Does the Wood Floor Expand in Summer or Winter?
Wood floors expand in the summer and contract in the winter. Wood absorbs moisture from the air, and the air in the summer is more humid than the air in the winter.
Conclusion
Understanding the dynamics of hardwood floor expansion and contraction is essential for maintaining the longevity and aesthetics of your flooring.
Hardwood floors can expand and contract due to factors such as wood species, grain direction, installation methods, subfloor condition, humidity, and temperature.
Feel free to reach out to us if you have any questions or need assistance with your hardwood flooring. Your floors deserve the best care, and we’re here to help!
