Ridge Vent
by Kenton Shepard and Nick Gromicko
One of the most efficient ventilation methods is the continuous soffit vent combined with the continuous ridge vent.
To form the ridge vent, a slot is cut out of the roof sheathing along the ridge. A fibrous material is installed over the top of the slot and held in place by a cap. The fibrous material will keep out insects while still allowing air to flow. The cap holds the fiber in place and diverts air.
Different manufacturers produce ridge vents in different configurations.
Although thermal buoyancy -- which is the tendency for hot air to rise -- will evacuate hot air from an attic space or rafter bay, ventilation is much more effective if the air is actively pulled out of the upper vents by other forces, such as air-pressure differentials.
When ridge vents have baffles, the baffles divert wind blowing across the roof upward. This creates an area of low pressure just above the opening, producing an air-pressure differential between the attic space and the exterior, which helps pull air out of the attic.
This effect is lost if the prevailing winds blow parallel to the ridge.
At the inspection, you may not know the direction from which prevailing winds blow. A home may have a well-designed system which is poorly oriented to the wind. In this case, it may be out-performed by a more poorly designed system which is better oriented to the wind.
You don’t have to know exactly how well the ventilation system performs, but knowing how systems are designed to perform may help if you find a problem that may be related to poor attic or roof ventilation.
You’ll find different types of continuous ridge vents installed. Whatever the type, you should check to make sure that the cap is securely fastened, since longer nails are required because of the additional thickness.
by Kenton Shepard and Nick Gromicko
by Kenton Shepard and Nick Gromicko
One of the most efficient ventilation methods is the continuous soffit vent combined with the continuous ridge vent.
To form the ridge vent, a slot is cut out of the roof sheathing along the ridge. A fibrous material is installed over the top of the slot and held in place by a cap. The fibrous material will keep out insects while still allowing air to flow. The cap holds the fiber in place and diverts air.
Different manufacturers produce ridge vents in different configurations.
Although thermal buoyancy -- which is the tendency for hot air to rise -- will evacuate hot air from an attic space or rafter bay, ventilation is much more effective if the air is actively pulled out of the upper vents by other forces, such as air-pressure differentials.
When ridge vents have baffles, the baffles divert wind blowing across the roof upward. This creates an area of low pressure just above the opening, producing an air-pressure differential between the attic space and the exterior, which helps pull air out of the attic.
This effect is lost if the prevailing winds blow parallel to the ridge.
At the inspection, you may not know the direction from which prevailing winds blow. A home may have a well-designed system which is poorly oriented to the wind. In this case, it may be out-performed by a more poorly designed system which is better oriented to the wind.
You don’t have to know exactly how well the ventilation system performs, but knowing how systems are designed to perform may help if you find a problem that may be related to poor attic or roof ventilation.
You’ll find different types of continuous ridge vents installed. Whatever the type, you should check to make sure that the cap is securely fastened, since longer nails are required because of the additional thickness.
by Kenton Shepard and Nick Gromicko