The basics of ventilation are quite simple, and most people already know that it is the flow of air through an intake and exhaust system. It was only in the early 20th century that builders realized that problems with building condensation could be caused by lack of proper roof ventilation.
Now, let’s find out why ventilation is important when it comes to your roof and how ventilation works for your home.
How does ventilation work?
Ventilation needs an air flow to work and there are two main ways of creating air flow in an attic. They are mechanical, which requires a power source and natural, which is used whenever possible. With natural roof ventilation the stack effect and the wind effect work together to create a natural circulation of air.
When hot air rises and creates a higher pressure at high points in the attic this is referred to as the stack effect. The hot air that is released is called exhaust, but hot air cannot escape without an inflow of cooler, low pressure air. This cool air that is drawn in is known as intake. The natural flow of air generated by the intake and exhaust create a well vented attic.
There are two main types of roof ventilation.
1. Exhaust vents, which allow the hot air to escape.
Ridge vents are the most common type of exhaust vent, and are installed at the top of the roof, known as the ridge. They are installed under a final layer of shingles making them almost invisible to the untrained eye.
Other exhaust vents are roof louvres, gable louvres and wind turbines, which don’t require electricity and power attic ventilators which use electricity.
Wind turbines need a constant source of wind to work well, but they are not as efficient as ridge vents.
Power attic ventilators operating on a power supply are an exhaust vent solution for some roof designs or areas with very little wind.
2. Intake vents draw in cool air.
Intake vents are installed at the edges of the roof, at the eaves, under the shingles at the roof’s edge or at the drip edge. Working with the ridge vents the intake vents allowing cool air into the attic space and forcing the warm air out through the ridge vents.
In our next article, we’ll explain exactly why ventilation is so important to your roof and your home. If you have any roofing questions give Asset Roofing a call. We are here to help you in Snohomish county, Redmond, Bellevue, and Kirkland.