Natural wood flooring is a feature that’s still desirable to many homeowners despite lower-cost modern alternatives. Properly maintained hardwood floors can last for generations. However, they are sensitive to environmental conditions such as extreme temperatures and high humidity in climates like Florida. During the hot summer wood expands, but when the temperature drops in the winter, it contracts again. This is normal, but over time extreme contraction/expansion can lead to cracking or warping.

The best way to combat this is to maintain consistent levels of indoor humidity. As an absorbent material, wood will tend to reach equilibrium with the moisture levels of the surrounding air. Consistently high humidity can swell the wood by as much as 15 percent, though wood tends to swell much more cross-grain that it does along the grain While the optimal humidity for interior conditions can change for different types of wood, seasons, and climates, it’s best to keep humidity somewhere in the 40 to 60 percent range to minimize contraction and expansion. This is similar to optimum comfort levels for people.

Winter Time

In the winter, while in general for Floridians the humidity usually does not get too high, it can at times be much dryer. Florida winters are prone to drought conditions and that can lead to much dryer air than we are used too. As such it’s increasing humidity in the winter when the air is dry may be beneficial to keep wood floors from shrinking too much. Otherwise, the wood is losing moisture and can contract enough so that gaps appear between the sawn planks. This should not be a cause for alarm if the gaps are small and close up when spring comes.

In warm regions, like Florida, winter dryness is less of a concern. Winter time humidity levels in the Sunshine State tend to stay between 55 and 60 percent. As long as humidity doesn’t fall below 40 percent, homeowners probably won’t even see any gaps.

Summer Time

However, summer time is just the opposite. Humidity levels through the summer tend to vary between roughly 80 and 90 percent. In interior spaces with wood flooring, humidity should be maintained below 65 percent. Wood can tend to absorb a lot of that moisture, and after just a few days of excessive humidity, wood planks can begin to expand and warp.

This is especially evident in “cupping”, where the edges of the planks expand against each other and tend to push upward, creating a convex surface down the middle of the plank. Even if the humidity is corrected, it can take some time for the wood to shrink back and regain it’s flat contour.

Other Moisture Risks

Crowning: This is when it’s the center of the plank that swells, producing the opposite effect of cupping. This can occur because of water soaking directly into the floorboards. It can also happen when cupping has left permanent ridges that are sanded off. When the wood compacts again, the middle of the board is higher than the edges.

Buckling: This happens when sections of the floor boards actually swell up and away from the subfloor, creating high and low spots. This is rare under normal conditions, but is likely to occur in homes that have experienced flooding, either due to weather or plumbing issues. Usually the only alternative is to replace the buckled planks.
Leaky roofs, bad plumbing, and even mild flooding in heavy rains can also damage wood floors. When that happens, fix the source of the leak, and mop or drain the water.

Use a dehumidifier and use a commercial drying fan in the affected area to remove excessive moisture. Also, keep in mind that damp wood is an invitation to mold, which can be toxic, and to termites, which can do extensive damage before you even know they’re there.

AC and Dehumidifiers

Hot air can hold more moisture than cool air. When moist air encounters cold objects, that moisture tends to condense onto the cold surface as a result of natural equilibrium. That’s how air conditioning helps to remove excess moisture from homes.

The warm, moist air from the interior deposits water droplets on the refrigerant-filled cooling coils. This water is allowed to drain away, thus continuously removing moisture from the home while the AC is running. A 12,000 Btu AC unit can remove three to four pints of water per hour. That sounds like quite a bit, but in high-moisture conditions, it may not be enough.

That’s where dehumidifiers come in. An AC unit is designed primarily to cool air, and 80 percent of its energy use goes toward that end. Dehumidifiers, however, are designed expressly to remove moisture. They work in a similar manner, by pulling in air across cooling coils and collecting the moisture. The cooled air is then reheated and returned to the room for better redistribution.

Though the process seems much the same, dehumidifiers have much lower energy demands than AC units – about one-tenth. Many new models also come with humidistats so you can set the desired humidity levels. There are also whole-house dehumidifiers. Both whole-house and portable dehumidifiers will raise air temperature slightly, forcing the AC to work a little harder.

But in Florida, summer means long months of very high almost tropical humidity. Dehumidifiers used at night or in specific rooms can help to sharply reduce moisture levels.

Caring for Your Floors

Wooden floors, especially natural hardwood floors, can add to a home’s value and visual appeal. They can be re-sanded and refinished whenever necessary. However, water damage is not so easy to fix and you should take special precautions to extend the life of your floors:

Do NOT clean wood floors with water, especially after sanding. Carefully sweep or vacuum them and use a new finish or cleaning product made for the purpose.

Do NOT let spilled water remain pooled on the floor. Wipe it up with rags or paper towels right away.

Run the AC and/or dehumidifier to maintain humidity levels.

Generally speaking, you want to use a dehumidifier during the drier winter months when humidity is high but interior temperature is not an issue. Run the AC in the summer, but be sure to have a means of measuring humidity to monitor for preferred levels.