Indoor Humidity in Cold Weather

Indoor humidity is affected by cold weather just like warm weather. Not preparing your home for the cold season can create humidity issues. Most of the time, a home will dry out in the winter. This seems like a good thing, right?

The problem is, you and your home need a moisture balance. Too moist and you get mold. Too dry and you get nose bleeds. The best advice I can give you is to keep your home’s humidity between 45% and 55%. Now let’s look at how to do that in cold weather.

Cold + Hot = Condensation

I was in a crawl space years ago and the outside temperature was in the teens. The crawl space temperature was in the 50s. It is unusual for East Tennessee to see whether that cold for an extended period of time. It was miserable. I was pulling subfloor insulation to address a mold problem. As I removed the fiberglass from the rim joist, I noticed the condensation everywhere.

Keep in mind, this was a vented crawl space that I was encapsulating. The high temperature inside the crawl space was due to very leaky ductwork. The homeowners kept the thermostat on the mid 70s with gas heat. The average ductwork leaks 25% so much of that 70 degree air was being pushed into the crawl space. It seems that a 50+ degree crawl space meeting 14 degree outside air at the rim joist can cause even wood to condensate.

Air Seal Ductwork

If you want to save money and make your home more comfortable, air seal your HVAC ducts. Not only will the home use less energy, but your home will be less likely to condensate in those unfinished areas. This includes attics, basements, crawl spaces and garages. Any space that is not conditioned but contains leaky ducts can create a condensation issue. A condensation problem leads to a humidity problem. A humidity problem leads to a mold problem.

Cold Winter = Low Humidity

Another problem homeowners face is humidity that is too low. Low humidity can create all sorts of problems. Here are just a few:

  • High bacteria growth
  • High virus outbreak
  • Respiratory infections
  • Allergic Rhinitis
  • Asthma attacks
  • Ozone production increase

All of the above listed issues become more of a problem when humidity dips below 40%. Nose bleeds can also happen more frequently. When you are running the heat and the weather is really cold, you may want to invest in a humidifier. I like room humidifiers if you keep them clean, but whole home humidifiers can be very effective as well.

Contact Crawl Space Ninja for Basement Waterproofing and Encapsulation

Please contact us to schedule your assessment to fix your crawl space, basement issue. 


Do you need help with mold removal, crawl space encapsulation, crawl space insulation, vapor barrier, waterproofing, foundation repair, basement waterproofing, or controlling humidity in your crawl space?

If you live in Georgia, Delaware, North Carolina, South Carolina, Tennessee, or Kentucky, Crawl Space Ninja can help!


Also, let us know in the comments below if you have an idea for a new blog topic.

DIY Crawl Space Repair

Perhaps you’d like to tackle your own crawl space repair. Visit our DIY Store.

Join Crawl Space Ninja as an Owner

Learn about Crawl Space Ninja Franchise opportunities.


Michael Church’s Crawl Space Repair Myths-Busted book was written to help you Avoid Bad Advice, Bad Decisions, & Bad Repairs.

“This book is the Cadillac for crawl space information and Michael Church is your experienced driver. What can I say? It’s just an amazing read.” 5.0 out of 5 stars The real deal.

Leave a Comment

Your email address will not be published. Required fields are marked *

Would love to help you with your next project! Schedule your Free Assessment today!

Scroll to Top