The Right Humidity Level

Posted on Wednesday, January 8th, 2014 by Nathan Weinstockwindow-frost-s-arrow-184x300

We are in the midst of winter here in Ottawa.  In fact, this is one of the coldest and snowiest winters we’ve had in a long time.  Winter weather provides a special set of home inspection considerations.  For instance, what is the right humidity level in the house?

In summer, we are often dealing with high humidity levels on hot muggy days.  Winter conditions can be just the opposite, too dry.  You can experience things like chapped skin, nose bleeds, and static electrical shocks.  The challenge is finding the right level of humidity in the winter.

You might be wondering can there be too much winter humidity?  Well, yes.  With too much humidity, you get water condensing on cold surfaces, such as on your windows.  Even your walls can get wet if the humidity levels get really high.  So the target moisture level would be in the range between 30% – 45%.

How do you know that you have the right humidity level?  You could invest in a hygrometer (an instrument used for measuring the moisture content in the atmosphere).  But we’re not talking about worrying about an exact number.  There is a simple trick you can use to tell if there is enough moisture in your inside air.  Simply look at your windows.

With the right humidity level, you should have a light mist or a few water droplets at the bottom of your window.  (Please see the picture.)  With no moisture, your house is too dry.  If water is pooling on the window sill, or running down the walls, then the house is too humid.  Keep in mind, I am talking about relatively new, energy efficient windows.  Older, less efficient windows often get covered in ice and do not provide a reliable reflection of humidity levels.

So there you have it, a simple test that can tell you so much.  If you find you have too much humidity, then you need to run some exhaust fans, or even briefly open a window, until you expel some of the moisture.  To find out what to do if your house is too dry, take a look at a previous log post:
Furnace Humidifier Gone Bad
Posted on Wednesday, October 5th, 2011