
Attic Ventilation is More Important Than You Might Think
Most homeowners don’t realize how important attic ventilation is to their comfort and utilities. It isn’t something you think much about until your electric bill skyrockets out of control. Or worse, you get a roof leak caused by wood rot from moisture in the attic.
Is attic ventilation necessary?
The answer is yes! To support that answer, we’ll talk about how attic ventilation works. With more knowledge about attic ventilation, you’ll understand the connection between attic ventilation and mold.
An attic that is completed sealed traps heat and moisture, too much in fact. And that shortens the lifespan of the roofing material, from the shingles down to the rafters and decking. Keeping the attic hot isn’t just bad during the summer though.
That heat and moisture are trapped in the winter months too, especially when there is insufficient attic insulation and lack of attic ventilation. Yes, even with ice and snow on the roof, your attic is still accumulating heat and moisture as the heat from the rest of the home rises.
Then that hot air melts the snow as the day warms up only to melt again at night. Then you have ice dams created, which can create leaks in the roof.
How does attic ventilation come to the rescue?
As we learn in grade school, heat rises. So, as your home is warm and toasty in the winter thanks to a great HVAC system, that warm air rises to the attic. Warm air is moist, and if there isn’t any attic ventilation, that moisture soaks into the rafters, under decking, and up into the roofing materials. There are two types of attic ventilation to pull that naturally risen heated air out:
- The intake attic vents: These are located under the eaves at the lowest part of the roof and cool air enters the attic through these vents.
- The hot air exhaust vents: These are located along the roof peak and the hot air escapes through these.
For attic ventilation to work though, experts recommend attic ventilation best practices, every 300 square feet of attic floor space, there should be 1 square foot of vents. Some building codes may differ, and contractors are usually familiar with these codes or know where to confirm that information. Other steps recommended to get the most from attic ventilation include the following:
- The intake and exhaust vents should be located so that air flows easily. This should be done with continuous vents running the entire length of the eave and ridge.
- The airflow should not be blocked or restricted by insulation or skylights.
- The airflow should be open from the eaves to the ridge between each rafter.
- If static vents are used, they should be spaced equally close to each other, allowing the entire attic to be ventilated.
- If necessary, use different types of intake vents and exhaust vents to create proper attic ventilation in coordination with the vent manufacturer’s instructions.
- The intake and exhaust for the attic ventilation should be balanced with the intake vents providing between 50% to 60% of the open ventilating area and the exhaust vents providing between 40% to 50% of the open ventilating area. The intake port of the attic ventilation should always be more than the exhaust to create a balanced attic ventilation system.
How to tell if you need more attic ventilation?
During the summer, heat buildup should be reduced when you have good attic ventilation so that cooling expenses are reduced, and asphalt shingles’ lifespan is extended. During the winter, the warm air from the living space rises to the attic. When you have good attic ventilation, that buildup of moist heat escapes, keeps the attic dry, and eliminates the possibility of ice dams forming.
These are four steps that will tell you if your home does not have proper or sufficient attic ventilation:
- Check the eaves around your home and along the roof peak. If there aren’t any attic vents in the eaves or along the roof peak, you need to have some installed. Who installs attic ventilation? If you’re getting a new roof or new siding, the contractor can install your attic ventilation. Or an HVAC specialist can install attic ventilation for you.
- From the inside of your home, touch the ceiling on a sunny day. If the ceiling is hot, then you don’t have proper attic ventilation.
- During the winter, if the eaves have thick ice ridges, you need more attic ventilation.
- During the winter, using a flashlight, inspect your attic. If you see dampness, moisture, or frost, your attic ventilation is insufficient. Who fixes attic ventilation? A professional roofing contractor will assess your home’s attic ventilation and provide you with the solutions to improve it, typically by installing either a roof ridge or gable vents.

Which attic ventilation is best?
For most homes, soffit vents for intake and a roof ridge vent for exhaust are recommended. However, not all homes will this type of attic ventilation work, so there is a box vent style that is the next best thing for the exhaust. If soffit ventilation won’t work for a home, fascia vents are the next best option.
For attic ventilation for metal roofs, gable, roof ridge, and intake vents are all needed. An experienced roofing contractor that works with metal roofing can determine what is needed for a home with metal roofing.
If you’re worried you may not have proper attic ventilation, be sure to give us a call at 817-781-8781.