Not Enough Ventilation In Attic

Just like properly sizing your furnace and air conditioning unit you want precisely the right amount of attic ventilation for your home.

Not enough ventilation in attic.

If the attic ventilation system is not a balanced combination of intake vents installed in the soffit under eave or at the roof s bottom edge and exhaust vents installed at or near the roof s peak the attic ventilation system will not be efficient and effective. Hot air fills the attic and raises the temperature. If a bath fan dumps into the attic that is very warm very moist air entering a cold space. The most dangerous source of moisture in your attic is from the home.

Attic ventilation only does an ok job removing moisture. If that air lingers it can cause condensation on the underside of the roof sheathing which can lead to wood rot and mold growth. Snow melts and the water refreezes on the cold eaves creating ice dams. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

Rafter vents should be placed in your attic ceiling in between the rafters at the point where your attic ceiling meets your attic floor. Insufficient ventilation can lead to moisture problems during the winter and decreased energy efficiency during the summer but too much ventilation can be just as bad if not worse. It s best to reduce how much gets there in the first place. Once they are in place you can then place the batts or blankets or blow insulation right out to the very edge of the attic floor.

For example attic ventilation is used widely even in cold climates to evacuate the warm moist air that escapes from the living space below. Touch your ceiling on a warm sunny day. Thick ridges of ice on your eaves in winter are a sign of poor attic ventilation. Warm air that escapes rooms below gets trapped in the attic.

Most building codes require a ratio of 1 150 ventilation space to attic floor space. You can also contact your local municipality to check on building code in your area. Intake vents located at the lowest part of the roof under the eaves allow cool. For instance in some places like las vegas the sun tends to set on the roof causing the attic to be warm.

If the vents aren t supplying sufficient circulation the temperature in the attic can rise to 140 degrees fahrenheit or more on sunny days and that can significantly affect the climate in your. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.