Do you want to know the best indoor humidity levels?
An overly humid home can make the skin feel clammy, increase perspiration, cause mold growth, and just make it uncomfortable.
In this guide, we’ll cover…
- The ideal indoor humidity
- How to control the home’s humidity
- Other tips related to humidity control.
Let’s get started!
What Is The Ideal Indoor Humidity Level?
The popular rule for ideal indoor humidity level for homes is between 30% to 50% according to the EPA, but absolute maximum humidity should always stay below 60%.
When the air gets thick with moisture above 60%, the moist air can lead to mold growth, clammy skin, condensation on the windows, and other issues.
And if the humidity level gets below 30%, the lack of moisture can lead to dry skin, allergies, cracked wood furniture or floors, static electricity, and other problems.
Homeowners will also want to fine tune this range based on the temperature outside in order to maximize comfort and reduce the chances of condensation. During summer, homeowners should opt to be in the higher part of the 30% to 50% range while during winter — it should be on the lower side.
I invite you to also read our guide on how to set a humidifier for winter right here.
Increase Humidity Levels To Reduce Airborne Viruses
A new study recommends that homeowners keep the indoor humidity on the higher side between 40% and 60% in order to reduce airborne viruses.
Water droplets contain naturally occurring anti-viral compounds such as hydrogen peroxide. The Stanford researchers were able to increase the quantity of natural hydrogen peroxide by a factor of 3.5 just by increasing the humidity from 15% to 50%.
It is hypothesized that increasing building ventilation in order to combat respiratory viruses has actually had a negative effect due to the decreased humidity.
In addition, when the air is dry, the virus particles are able to remain airborne for much longer periods. When the air has higher humidity, the water droplets weigh down the viruses and helps bring them down to the ground (and out of our lungs).
The Best Humidity During Summer
The ideal humidity during summer is in the 40% to 50% humidity range. A slightly higher humidity will help the air feel cooler and can allow homeowners to slightly increase the A/C temperature setting without sacrificing comfort.
The ideal summer setting is slightly on the higher side of the general humidity recommendation for homes. In fact, the biggest problem during warm weather is to keep indoor humidity lower and at least below 60%.
If the home’s humidity rises above 60%, it will make for an uncomfortable environment and may lead to mold problems.
Homeowners best bet to lower the humidity during summer is to reduce the A/C temperature since air conditioners naturally dehumidify the air when on.
If the A/C system is having trouble dehumidifying the air, it may just be an old system that needs to be upgraded or you may need to clean the outdoor condenser, the indoor A-coil, the indoor blower fan etc. Just cleaning the A/C system can improve the efficiency of the system and which most homeowners neglect.
Another option is to install a whole house dehumidifier which connects to the HVAC duct system or just use one or more portable dehumidifiers.
Ideal Humidity During Winter
For most parts of the USA, where the winter temperature doesn’t drop below 10°F, the ideal humidity during winter is in the 30% to 40% range.
However, if the outdoor temperature gets very cold, it is important that homeowners consider lowering the indoor humidity to below 30%. If indoor humidity remains high, there is a good chance that condensation (water droplets) will form inside the house.
Condensation or moisture may form on the windows, around the exterior walls, and other areas of the home that may lead to moisture damage or mold growth. If at any time the windows are fogging up or forming condensation, homeowners should immediately lower the indoor humidity!
Below is a chart with the recommended humidity as the outdoor temperature drops to below zero.
| Exterior Temperature | Ideal Indoor Humidity |
|---|---|
| +40°F | 45% |
| +30°F | 40% |
| +20°F | 35% |
| +10°F | 30% |
| 0°F | 25% |
| -10°F | 20% |
| -20°F | 15% |
| -30°F | 10% |
Winter Appliances To Control Humidity
The top appliance that homeowners can buy to increase humidity during winter is a whole house steam humidifier. Steam is a high quality source of humidity as compared to evaporation but standard ‘evaporative’ whole house humidifiers also work well.
These devices are installed near the furnace and attached to the HVAC duct system. The humidity level is controlled with a simple control panel.
You may want to read our guide on whole house humidifiers and mold to learn about reducing mold growth when using one.
Humidity Level in the Basement
The ideal humidity level for a basement is in the 30% to 50% humidity range.
Basements sometimes become vulnerable to high humidity due to the fact that part of it is underground.
On the exterior, if the ground improperly slopes towards the home, this can funnel excess moisture into the basement. In addition, if the downspouts are missing extensions and draining too close to the home, this can also funnel water towards the basement and increase the humidity.
I invite you to also read our guide on how bathroom fans with humidity sensors can automatically turn on and reduce moisture levels — especially for basements.
What Humidity Level Is Considered Too High or Uncomfortable?
When the humidity rises to 55%-60%, the air will begin to feel ‘sticky’ and the discomfort will only get worse.
If moisture levels get to 65% or higher, it can begin to feel oppressive. If indoor humidity rises above 75%, it is equivalent to being in a tropical jungle.
Is 50% Humidity High?
50% humidity is at the top of the range for the ideal humidity range (30% to 50%) but it is still well below the maximum recommendation of 60% RH.
Anything above 60% is considered abnormal and it may lead to mold growth. Unusually high humidity can also damage wood framing, wood floors, and furniture.
Homeowners should always at a minimum strive to keep indoor humidity at or below 60%.
Conclusion
Even though indoor comfort is ultimately an individual preference, the ideal indoor humidity falls between 30% to 50% for most people. The absolute maximum indoor humidity recommended by the EPA is 60%.
If indoor humidity gets above 60%, the chances of condensation forming inside the home are quite high.
Indoor moisture can lead to mold growth, damaged furniture, cracked wood floors, hardware rust, and other problems.
It is essential that homeowners lower indoor humidity as the outdoor temperature drops below 10°F. When it gets very cold outside, and if the indoor humidity remains high, condensation will also likely form on the windows and other areas of the home — possibly leading to mold growth.