What percentage of humidity should your house be?

Humidity refers to the amount of water vapour that is present in the air. The percentage of humidity inside a house not only determines how comfortable and healthy the air is for inhabitants, it also affects such important issues as mould growth and can actually damage a home's interior.

Proper Indoor Humidity Percentage

According to the U.S. Environmental Protection Agency (EPA), the correct indoor humidity level is in the range between 30 and 50 per cent. The humidity inside a house should be adjusted accordingly so it remains within these percentage levels. If the humidity level inside the house is high, but the humidity level outside is not, open a window to allow in fresh air. Raise the humidity inside the house, if necessary, by using a humidifier or vaporiser.

Monitoring Humidity

Monitoring humidity is the key to knowing when the level should be altered. To gauge the humidity levels inside your house, you can use a portable hygrometer, which allows you to move it from room to room and monitor the humidity level in each one. Hygrometers are instruments that measure the amount of relative humidity in the air, and they are available in digital versions. You can purchase them online or from your local hardware store.

Noticing Humidity Changes

Normal household living activities usually add enough moisture to the air to maintain indoor humidity at the correct level. These activities include cooking and washing clothes and dishes, or human breathing and perspiring, which should all allow the humidity to stay at a comfortable level. If the percentage of indoor humidity is too high, you will likely notice it through condensation on the insides of windows, or mould growing on walls. If the percentage of humidity has dropped too low, you may notice too much static electricity in your clothes or the carpet.

Effects of Unbalanced Humidity

If the percentage of indoor humidity is not at the correct level, you may also suffer physical effects, and the house itself may exhibit effects. If the level is too low, under 30 per cent, you may have a bleeding nose, persistent respiratory problems or an infection that is caused by your mucous membranes drying out. Just as a high percentage of humidity --- over 50 per cent --- fosters mould growth and encourages pests such as termites and cockroaches, a percentage that is too low leads to cracks in plaster and drywall, as well as shrinkage in wood flooring and other wooden objects.

Cite this Article A tool to create a citation to reference this article Cite this Article

About the Author

Christopher John has been a freelance journalist since 2003. He has written for regional newspapers such as "The Metro Forum" and the "West Tennessee Examiner." John has a Bachelor of Arts in journalism from Memphis State University.