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Frost, Condensation and Whole House Humidifiers

Updated: Jan 20, 2022

Imagine for a moment, you just had a new roof installed, spent thousands, it's now winter and you have a roof leak...or so you think...

This winter we've experienced some pretty harsh conditions. Our office has taken an abundance of calls with concerns of what is thought to be a roof leak. Obviously, when you notice water intrusion, your first conclusion is to assume it's the roof- which makes sense. While it's a great idea to have your roofing contractor come out to assess the issues to narrow it down, did you know the cause of your problem may not be your roof at all? It could be your whole house humidifier. We know...this is shocking to most customers. Let us explain.

Many homeowners experience dry air inside during winter and are looking to add some comfort within the home. The most obvious solution seems to be installing a whole house humidifier. While a whole house humidifier is a great way to add moisture, as we've always said- moisture equals big problems, if uncontrolled.

Too much moisture can cause major problems such as mold, mildew, large amounts of condensation (pictured below) damaging your insulation resulting in insulation extraction and re-installation, damage to roof decking, drywall and more. In some instances, moisture can damage your home beyond repair, as we've seen in some cases in recent weeks.

Are Whole House Humidifiers Bad?

Well, not exactly. While it may be a better idea to get a table top or portable humidifier, whole house humidifiers can add comfort to your home, when used correctly. Make sure you ask all the right questions when having a whole house humidifier installed. Don't always rely on your HVAC technician to give you these small, but important details. The most important and maybe only defense against issues is to know what the humidity levels should be set at based on outside temperatures.

According to Reuben Saltzman, Minnesota Home Inspector, if the outdoor temp is 20 degrees, set your humidifier at 35%. If temps outside fall to 0 degrees or below, set it at 25%. This should be done prior to the temperature drop.

So, How Do You Know It Could Be Your Whole House Humidifier?

1. Staining or streaking along walls and/or ceilings, especially if the streaking is along the extent of the room and appears to be along a beam.

2. Excessive window condensation

3. Frost in your attic (pictured below). This could be a couple things- lack of insulation or ventilation but is most commonly caused by a whole house humidifier being set too high in sub zero temperatures.

4. It's "raining in your attic." This typically occurs after that frost (mentioned above) melts, causing water to drip from the decking's nails.

These are just a few things to look for if you experience moisture and just so happen to have a whole house humidifier. It's better to stay ahead of the moisture problem rather than find out too late that you could've potentially prevented the issue.

It's important to note that if the cause was indeed your whole house humidifier, adjusting the setting may not eliminate the issue right away. Any condensation that's up there now will re-freeze and thaw again with the warmer temps we're seeing. You may not see any change until Spring or Summer when your attic heats up enough for that condensation to eventually evaporate.

So, if you're still stuck on the idea of getting a whole house humidifier, just make sure you are educated on what the proper settings during each season.

As always, ABC Roofing is here to help educate our homeowners and would be happy to come assess your concerns, free of charge. Our team is one of the most knowledgeable in the state!

Frost on decking

Condensation on Roof Decking

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