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Attic Ventilation Installation

There are many roofing companies that perform ventilation installations incorrectly. We know this because we correct attic ventilation installation issues on dozens of houses every year. So why does this happen? It happens because companies are pushed to install products they are not trained to install and the result can be very costly.

Here are a few very simple things to keep in mind when speaking with a contractor about ventilation:

1) You need 1 square-foot of ventilation for every 150 square-feet of ceiling space that does not have a vapor barrier or 300 square-feet of ceiling space that does have a vapor barrier. That is the standard formula known throughout the construction industry.

2) An approved vapor barrier has a perm rating of 1 or less. There are vapor barrier paints that have a perm rating of 1 or less. These allow your ceiling to meet the vapor barrier code with just a coat of paint. Uncommonly known, multiple coats of any paint will provide a perm rating of less than 1, so most ceilings will require 1 square-foot of ventilation for every 300 square-feet of ceiling space. The paint manufacturers do not specify that information because they would have to test every color.

Other things to consider:

The type of attic ventilation and it’s construction are critical for success. You should not mix ridge vents with gable vents. A gable vent will short circuit a ridge vent and vice versa. Ridge vents were designed for cathedral ceiling construction, but they can be used with flat ceilings. Gable vents are considered an old construction technique and when sized right, they will provide adequate ventilation. However they often require modifications to prevent future leakage which can compromise the ventilation of the building.

There are several ways to monitor the ventilation of your attic space. First, look underneath the roof sheathing. As long as there is no mildew, you are in good shape and no ventilation improvements may be required. An important place to look for mildew is around your roof nails, because they attract condensation through temperature transfers. If there is no sign there, you should be in good shape, but keep an eye on that if you are new to your home. Pay attention to bathrooms or laundry areas that dump their ventilation into the attic, as this is a common problem in regards to moisture dissipation. (Tip: Invest in bathroom and laundry fans to direct their exhaust outside).

Temperature & Ventilation:

Your attic space should be the same temperature and humidity as the outside of the house during the winter months. Ventilation is most important during months of Fall through Spring. People make the mistake of blocking ventilation in their attics, thinking that they are saving energy. Your insulation performs the best when it is dry, with no additional moisture. Just by adding 10% humidity to your insulation, you are reducing its R value by 50%. The moisture becomes a conduit for energy loss and presents a strong potential for an outbreak of mold.

If your goal is to make the attic space cooler in the summer, it would be difficult with a passive system such as soffit, ridge vents, or gable vents. They are designed to keep the space dry when and if it gets wet. You will need a temperature controlled attic fan, either electric or solar to reduce the attic temperature in the summer. This product will make your attic space equal to ambient air temperature once the sun goes down, preventing a hot attic from radiating down into the living space all night long.

Balanced attic ventilation installation is critical, as well as choosing the right product for the job; otherwise you can end up with moisture or small snow particles in your attic space, which is a real problem if you do not have access to that space. Give us a call at 1-888-618-3271 and we will make sure that your house has the right attic ventilation system to to ensure efficiency and safety.



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