Australia Storm Book

After The Storm - 25

Roof Repairs: Ventilation

General

Just as we breathe to live, a house must breathe also. This means the roof must be ventilated well and correctly. Basically what is required is a continuous flow of air through the attic or roof system at all times. That flow enters at the eaves through the soffit vents and rises as air warms during the day and passes out of high ridge area vents. The air collects moisture vapor and built-up gases and expels them from your house, maintaining a healthful environment for both you and the structure of the house. Moisture and health problems are possible when adequate ventilation is not provided.

Louver and vent openings should not be covered during the winter. Eaves or soffit vents should not be blocked by insulation.

Vent openings should conform to or exceed current construction standards. These usually call for a minimum of 1 square foot of free vent opening for each 150 square feet of attic surface where the attic has no vapor barrier. If a vapor barrier is present or if half of the vent openings are along the ridge and the other half at the eaves or soffit, a minimum of 1 square foot of free vent opening for each 300 square feet of attic space should be provided. On mansard roofs, ventilation ratios should be at least three times those stated above.

When calculating the net free vent opening, be sure to take screening into consideration because screens can significantly reduce the free area of the vent.

Again, there are many types of soffit, ridge-area, and gable vents. The most effective system, which uniformly ventilates the entire roof as needed, is the system of continuous soffit vents coupled with a continuous ridge vent.

Provide a good ventilating system for your new roof for:

Your continued health.
Prolonging the life of your roof by continuously cooling it.
Cutting your cooling bills by venting out hot air.
Removing moisture vapor from within your attic and home to prevent moisture problems.

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