How Frost/Condensation Form in Your Homes Attic?

Roof-Tech - How frost condensation form in your homes atticTis the season for attic ventilation problems to become visible, and they become visible because they cause frost to form in the attic on these cold winter nights. Otherwise here in Omaha, your improperly vented attic space don’t have a face like frost and won’t cause you any real noticeable problems in the summer, most of the spring and fall.

This is mainly due to the outside air temperature is not cold enough to cool the outside of roofs surface to a point where the moisture in the attic will turn to frost on the inside of the surface of the roof.

When discussing the process of how moisture can get trapped in your attic, it can get technical. The fundamental principle is that the colder the air, the less moisture it will hold. Which means, if your attic does not have proper ventilation, it will hold more moisture than it should. On cold winter nights, frost will form on the underside of the roof surface. When the sun rises in the morning, the roof surface will start to heat up, melting the frost into water causing a rippling effect of the water raining down onto the insulation.

Depending on how much moisture is present in the attic air and how cold it is outside will dictate when the frost will occur. The more moisture in the air the higher the temperature can be to cause a problem.

When Attic Ventilation Problems to Become Visible - Roof TechYou might ask, “How does enough moisture get in my attic to cause problems?”

The most common contributor is your bathroom fan. Think about it, you turn on the shower in the morning and get that water as hot as you can, and the bathroom fills with steam, so you turn in the fan, so the mirror doesn’t fog up.

Where does that steam, or air with a lot of moisture go?

I can tell from my years of climbing around attics finding the causes of roof leaks. It almost always goes into the attic. Very rarely are those bathroom fans vented out of the house properly. Usually, they have a dry vent hose connected to the back of them, and the end of the house is nailed to a rafter in the attic or is ran out into the soffit.

Moisture also gets into the attic from humidifier adding water into the home’s air. If you have a whole house humidifier attached to your furnace and you don’t know what you should have it set at, there’s a chart to the right. A good rule of thumb is if you get condensation forming on bottom inch of your window, there is too much humidity in the house.

Did you know that The National Bureau of Standards says that a family of four typically produces two to three gallons of water vapor a day?

The Fix:

1. Attempt to reduce the amount of moisture in the home from getting into the attic. Next, add proper bathroom fan venting and be sure to check the settings on the humidifier, if you have one.

2. Then, if the problem still exists, address the intake and exhaust vent situation for the attic. The vents are more than likely clogged and needed cleaning or your home might need additional venting.

3. Lastly, re-insulate the attic space. Wet insulation loses its R-Value, and if the attic has had frost and condensation problems in the past, the insulation has been wet, and no longer is working to its designed potential.

Do you have additional questions regarding your attic space or roof? Give us a call today at (402) 896-5554.

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