Controlling Winter Humidity: Common Misconceptions!

There are many misconceptions about what level of humidity is appropriate for your home in the wintertime. The more customers I talk to, the more I understand how confusing it can be to get the most enjoyment from your home.

From flooring websites that recommend humidity levels of 35% to 55% without explaining the connection to outdoor temperature, to health practitioners who are telling their clients to crank up the humidity, it can be pretty confusing.

So what is “Relative Humidity”? It is the ratio of the amount of water vapor in the air at a specific temperature to the maximum amount that the air could hold at that temperature, expressed as a percentage (or a bit more simply, it is the ability of air to hold water vapour).

Warm air can hold more water vapour than cold air. When warm air carrying a high level of humidity runs into a cold surface, you get condensation. If we reduce the level of humidity in that warm air, there is less chance for condensation.

Here’s the thing: Homes today are built very different from the homes of even a few years ago and that’s a good thing. We are able to provide our customers with healthier, quieter and more energy efficient and durable homes than ever before. At the same time, the homes are much tighter and they react differently than older homes. Because there are far fewer air leaks, there is much less cold dry air entering the home, which means they don’t dry out the same as older leaky homes and controlling excess humidity becomes a much higher priority.

In the summer, indoor humidity can range anywhere from 40% up to 55% depending on how warm the air is in the home. In the winter, that level of humidity on a really cold day will cause condensation on windows and other cold surfaces such as exterior door handles. We recommend a typical wintertime humidity level between 30% and 40%, with it dropping under 30% on extremely cold days.