Proper attic ventilation should be an essential part of your home’s design. Proper attic ventilation is required to validate the shingle manufacturers warranty. Proper attic ventilation can save you money all year long.
In the summer month’s attic ventilation can help reduce heat buildup. Having the attic cooler can help make the living areas cooler, which can help reduce air conditioning cost.
In the winter month’s attic ventilation can help reduce moisture buildup. Moisture buildup in the attic can lead to wood rot, mold, mildew, and poor indoor air quality. It can also help prevent ice dams.
In order to create proper attic ventilation we need a balanced system of intake vents along with exhaust vents. Intake vents would be at eve or soffit. Exhaust vents would be at or near the ridge. The best way to address ventilation is to have a continuous intake and exhaust vents. Two products that I recommend to achieve this are: The Edge Vent & Shingle Vent II. Air Vent Inc manufactured both.
The Edge Vent – Provides 9 sq in per lf. It is installed at the eve of the roof with shingles installed on top of it. This can be an excellent intake vent for a house that does not have an overhang.
Shingle Vent II – Provides 18 sq in per lf. It is installed at the ridge with shingles installed on top of it. Shingle Vent II has a built in external baffle that deflects wind up and over the vent helping to pull stale air from the attic. As long as there is enough lf of ridge Shingle Vent II will be the best match for an exhaust vent.
On hip shaped roof, one that has 4 sides, I would recommend installing a power vent for the exhaust vent. You can choose between electric or solar powered. On an electric power vents make sure that it comes with a humidistat/thermostat so that it will also work in the winter months. Some models are made with only a thermostat; these models will only run in the summer when the attic temperature rises (this leaves the moisture in the attic in the winter months). Solar power vents do not have humidistat or thermostat controls. Solar power vents run whenever they get sun exposure.
This biggest mistake people make when it comes to ventilation is to install multiple types of exhaust vents over the same attic space. You only want one type of exhaust vent. Having multiple exhaust vents like ridge vents and gable end vents are counter productive and short circuit the airflow. You want to achieve airflow from the eve to the ridge not from the ridge to the ridge.