Attic Rain
Attic rain is a phenomenon that occurs when water leaks from the attic of a building. It is due to frost build up on the sheathing or other areas of the attic. Most attics in our climate will experience some frost in the attic during very cold temperatures, a well ventilated attic should naturally get rid of the frost build up as the temperature gradually gets warmer. Unfortunately our climate experiences drastic changes in temperature where it can fluctuate from -30 to above 0 in 24 hours. When that happens the attic ventilation doesn’t have time to get rid of the frost buildup and it will melt and can cause water damage to your home.
There are ways to help prevent attic rain and frost build up. One of the best ways to stop it is to minimize any air that leaks into the attic. Some of the main places that this occurs is around your exhaust vents
(bathroom fan, dryer vent etc.), so ensure they are perfectly sealed (vapor barrier) all the way until it meets the sheathing. Another common place air leaks is through your attic hatch, make sure it is well sealed and insulated. Air can also easily enter through any light fixture that doesn’t have a proper vapor barrier around it.
Another way to help prevent attic rain is to ensure your home isn’t too humid. That means keeping your humidifier very low or off when temperatures outside are very cold. Even with the humidifier off your home can be too humid just from showering, cooking, plants and even breathing. That’s why the use of your bathroom fan and hoodfan are very important to help get rid of that moist air. If you have a heat exchanger/HRV unit they can be a great tool for you as they can work to dehumidify your house.
The ventilation of your attic is critical to its overall performance and condition. There needs to be one square foot of ventilation per 300 square feet of attic space.
If you are unsure if your attic space has the proper seals and ventilation you can always have a home inspector, preferably House to Home Inspections of course, perform an inspection on your attic.
