What Homeowners Need to Know About Roof Ventilation
Inadequate ventilation leads to excess moisture, which can cause degradation of your roof. Learn the proper approaches and benefits to roof ventilation so you can make an informed decision.
On this page, we'll discuss...
- How roof ventilation works
- Ventilation systems
- Calculating ventilation space
- Benefits of proper ventilation
How Roof Ventilation Works
Ventilation involves combining various types of vents and fans throughout a house in order to keep air moving steadily.
The goal is to draw warm, humid air out of the attic while replacing it with cooler, drier air. Doing so reduces the humidity levels in the attic, therefore reducing the amount of moisture damage to the underside of the roof.
This is typically accomplished with exhaust and intake vents. Exhaust vents are located in or on top of the attic and help warm air flow out from the roof. They include ridge vents, roof turbines, and gable vents. Intake vents assist in drawing cooler air through the soffit, eaves, or even the foundation.
Proper attic ventilation provides year-round benefits to homeowners, helping to prolong the life of roofing materials while keeping utility bills down and improving the quality of life inside the home.
An attic with regular air flow helps fight excessive summer heat, moisture buildup in the winter, as well as reducing ice dams.
The best forms of attic ventilation occur when an equal amount of air is coming in through the intake vents and going out through the exhaust vents. This allows cool, dry air to enter the attic at its lowest point and pushes warm, moist air through the attic and out the exhaust vents.
Attic Ventilation Systems
Ridge and Soffit Vents
Vents installed under the eaves of the soffit and along the roofline allow for proper passive ventilation. This simple system allows fresh air to flow in, up, and out of the attic.
Fan Powered Roof Vents
These electric fans are very similar to ridge vents, only they can be operated manually or programmed to run when a predetermined internal temperature has been reached.
Attic Exhaust Fan
Attic exhaust fans are installed in the gable of the attic rather than along the ridge of the roof. This system usually requires extra ventilation due to the amount of hot air they blow out, and in turn fresh air they draw in. This system can greatly reduce energy costs for homeowners.
Turbines are installed on top of the roof and use wind power to draw hot and humid air out of the attic. Roof turbines have a series of vanes that spin when the wind passes through them, and this movement creates ventilation. In an area with a lot of air movement, turbines offer a great solution.
Learn more about ventilation systems: Roof Ventilation: Roof Turbines and Ridge Vents
Calculating Attic Ventilation
Before deciding which ventilation products are right for your home, you’ll have to calculate how much ventilation is needed.
Almost all building codes call for a ratio of 1/300 — For every 300 feet of attic floor space, there should be 1 square foot of ventilation space.
As an example, let's determine the necessary ventilation space for an attic measuring 25 ft. x 50 ft.
25 ft. x 50 ft. = 1,250 sq. ft. of attic floor space
1,250 ÷ 300 = 4.16 sq. ft. of ventilation space
A balanced ventilation system should always be the goal. The amount of exhaust ventilation should never exceed the amount of intake ventilation.
Learn more about inspecting your roof: What You Should Know Before Attempting a DIY Roof Inspection
Benefits of Proper Roof Ventilation
Proper roof ventilation allows cool, fresh air to enter the attic, and expels hotter, moist air through exhaust vents.
This cycle plays a key role in prolonging a roof system and prevents many expensive problems both inside and out.
In colder climates, proper ventilation mixes cool outside air with the warmer air from the attic, allowing for less snowmelt. This prevents problematic ice dams.
In warmer regions, regular air flow helps expel moist air, which can lead to rot, mold, and other forms of deterioration.
In general, proper ventilation should:
- Reduce damaging moisture
- Allow for increased savings on utilities
- Prevent early roof deterioration
- Decrease ice dams
- Moderate internal home temperatures
Learn more about how to hire the right contractor for your home:
Costs of Roof Ventilation Systems
|Static vents||$35 - $50 per vent installation|
|Roof turbines||$70 - $200 per turbine installation|
|Gable vents||$45 DIY installation / $185 professional installation|
|Soffit vents||$375 professional installation|
|Ridge vents||$245 professional installation|
|Whole-house fan||$1,000 professional installation|
The cost of roofing ventilation systems varies depending on a number of factors, including:
- whether you DIY or hire a professional
- whether you choose an active or passive system
- the size of your home
Roof Ventilation Maintenance
Once you determine what roof ventilation system works best for your home, it should be checked annually to ensure it runs at full capacity.
Follow a regular maintenance program to ensure your ventilation system is in good condition.
- Clear the vent screens of dirt and debris.
- Check for rips or tears.
- Inspect for rust around the framing.
- Clear insulation away from vent openings.
Learn more about the costs of roof repairs and replacements: