If you have a spray foamed attic, one of the most important items is humidity control. Humidity build up can be a the silent efficiency killer of a spray foam attic system.
Since we are in Florida; and this apples to most humid areas of the country, the humidity can be out of control 9 months of the year. When you have a spray foamed attic, it is important to have your attic at a humidity level of 50-60%. 45-50% would be very idea and is very difficult to achieve, almost a pipe dream spray foam, but not always attainable.
If your attic is 50-60% relative humidity, you are good.
Below are several humidity sources, and how you should address them.
Bathroom Fans
All bathroom fans should be air sealed with spray foam and or mastic. If you have a bathroom that is leaking into your attic, you are going to allow very high humid air from your bathroom, plus foul air to be blown into your attic and increase your humidity levels.
Seal all bathroom fans with metal HVAC tape and or mastic.
Dryer Vents
It is important to have your vent for your clothes dryer cleaned yearly and sealed with the proper dryer tape. One load of wet cloths can potentially vent 5-9lbs of water vapor into your attic.
Make sure you have the follow areas addressed with dryer vents.
- Each bend should be taped and sealed.
- Each connection should be taped and sealed.
- The vent out to the roof or side of home should be sealed and not venting into your home.
- It is recommend to keep your dryer vent less than 25-35′ with less than two 90 degree bends, but always follow local code.
- Clean your dryer vent once a year.
HVAC Ducts and Duct Boots
Air ducts are super important to keep conditioned air in your home. Whether you have spray foam or a blown fiberglass or batted home, having the proper sealed air ducts are critical. Make sure all your air duct and duct boots are properly sealed for efficiency.
Gable Vents and Soffits
When a spray foam company installs spray foam, the attic has to be 100% air sealed. All the soffit vents, gable vents , doors, ridge vents, EVERYTHING has to be sealed over with foam. Air, especially hot air has the potential to contain a lot of hot humid moisture. You do not want any entry points for hot humid air into your home.
When inspecting for air leaks, check the following:
- Garage attic access to the attic
- Soffit access
- Soffit areas
- Vents
- Fans
- Gable vents and gable wall
- Hips roofs
Dehumidifier – Sometimes a last resort
There are other ways to reduce your humidity if all these items have been checked off. Install a 75-110 pint per day dehumidifier. A dehumidifier is a great way to reduce unwanted humidity in your attic.
If you are experiencing high humidity in your spray foam attic, call me directly at 407-775-2230.
