Have you ever looked down at your timber floor and noticed gaps between the boards that weren’t there a week ago? If you have, don’t worry. You’re most likely observing your floor’s natural response to dry weather. In this guide to what happens to timber floors in dry times, we look at how changing humidity affect timber floors, as well as the steps you can take to protect your timber floors in dry weather.
What happens to timber floors in dry times?
It’s common for timber floors in dry times to look noticeably different from other times of the year. As a natural product, timber floors expand and contract with changes in the relative humidity level of your house. Relative humidity is a measure of how much moisture is in the air, with lower levels indicating the air is dry and higher levels indicating there is more moisture in the air.
In the same way that changing humidity levels can cause cupping, peaking and crowning, drier air (i.e. lower humidity conditions) can make your floorboards contract, leaving visible gaps between the boards. This is because low humidity levels cause moisture to move out of the floor and into the air, reducing the volume of your timber floors in dry weather. In the case of floating floors, sudden drops in humidity can cause the ‘rafts’ to shrink and potentially pull out from beneath scotia. Occasionally, the floor may also separate if movement has not been fully allowed for during installation.
The graph below highlights this relationship between relative humidity (RH) and moisture content (MC). As you can see, the cover width of the floor boards is 1.5mm smaller when the relative humidity is 40%, than when the humidity level is 80%.
Day-to-day, timber floors respond slowly to changes in humidity levels, so you typically won’t observe much of a change. However, during periods of significant humidity changes—such as changing seasons—shrinkage is more noticeable. For instance, Brisbane tends to be relatively dry during September, while the southern parts of Australia tend to be at their driest over the Christmas period and late into summer.
How you can protect timber floors in dry times
More often than not, board shrinkage due to dry conditions will be minor and resolve by itself as the air becomes more humid again. However, there are a few things you can do to protect timber floors in dry times to prolong the lifespan of your hardwood floors. These include:
• Limiting how much air flows through the house during the driest part of the day. Because timber floors lose the most moisture when the air is at its driest, you should limit the amount of breeze that flows through the house during the driest part of the day. Typically, this will be in the afternoon. Instead, ventilate the house in the morning or evening when the air is more humid. This allows cool air into the house and limits the amount of moisture that escapes from the boards.
• Increasing the relative humidity level within your house. Adding more moisture to the air will limit the amount of moisture that is drawn out of your timber floors in dry weather.
• Strategies to raise the humidity level within your house include opening the house up at night to let cool, moister air inside, using a portable evaporative cooler or leaving out bowls of water.
• Reducing heater use during cold, dry weather. As tempting as it is to run the heater to warm up over the cooler months, heater usage can create even drier internal conditions.
• Ensuring that the house is well-ventilated if timber floors are being installed over a hot, dry summer, to prevent the temperature within the house from becoming too hot.
Australian Timber Flooring Association Inc., 2018, Timber floors in dry times