Roof Ventilation 101: Intake vs. Exhaust Vents Explained
When most homeowners think about their roof, they picture shingles, flashing, or gutters—not the airflow beneath it. Yet proper roof ventilation is one of the most important (and most misunderstood) parts of a roofing system. If you’ve ever wondered what “intake” and “exhaust” vents actually do—and why your Maine home needs both—this guide will break it down simply and clearly.
Why Roof Ventilation Matters
Maine weather is beautiful, but it’s brutal on roofs. Heavy snow, humid summers, and frigid winters all put pressure on your attic space. Without proper ventilation, warm air and moisture get trapped, leading to:
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Ice dams that force meltwater under shingles
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Mold and mildew in attic insulation
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Warped roof decking
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Shortened roof lifespan
A balanced system of intake and exhaust vents keeps your attic dry and your roof healthy, no matter the season.
The Basics: How Air Moves Through Your Attic
Think of your attic like a chimney system—it only works when air can flow in and out efficiently.
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Cool air enters through intake vents (usually located along the soffits or eaves).
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Warm, moist air exits through exhaust vents (near the peak or ridge of the roof).
This continuous airflow keeps the attic temperature closer to the outdoor temperature, preventing condensation, heat buildup, and structural stress.
Intake Vents: The Unsung Heroes
Location: Under the eaves, in soffits, or occasionally low on the roofline.
Purpose: Bring in fresh, cool air to replace the hot air that rises and escapes through exhaust vents.
Common Types of Intake Vents:
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Soffit vents: Continuous or perforated panels installed under the roof eaves.
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Gable vents: Decorative and functional vents on exterior walls near the roofline.
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Edge vents: Used when soffits are absent or enclosed.
If you only have exhaust vents without proper intake, your roof may actually pull air from inside your home—raising your energy bills and increasing moisture problems.
Exhaust Vents: The Release Valves
Location: Near the roof ridge or highest point of your attic.
Purpose: Allow warm, humid air to escape naturally as it rises.
Common Types of Exhaust Vents:
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Ridge vents: Continuous vents running along the roof peak, offering the most even airflow.
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Box vents (or static vents): Fixed openings placed near the ridge to release trapped air.
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Power vents: Electrically or solar-powered fans that actively pull hot air out (often used in large or complex roof designs).
Balanced exhaust ensures that hot air doesn’t linger in the attic, which can prematurely age shingles and cause uneven roof temperatures that lead to ice damming.
The Key Is Balance
The golden rule of attic ventilation is simple: intake and exhaust must work together.
If you have too much exhaust and not enough intake, you’ll create negative pressure that draws conditioned air from your living space into the attic.
If you have too much intake and not enough exhaust, the air becomes stagnant, defeating the purpose of the system altogether.
A professional roof inspection from A Plus Roofing ensures your vent system is balanced, code-compliant, and perfectly suited for Maine’s demanding climate.
How to Know if Your Ventilation System Needs Help
Watch for these warning signs:
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Ice dams forming on the roof edge
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Moldy or damp attic insulation
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Uneven snow melt on the roof
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Musty smells or excess heat in upper rooms
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Rusted nails or condensation on attic rafters
If any of these sound familiar, it’s time to have your roof evaluated by a ventilation expert before small issues turn into costly damage.
The A Plus Roofing Advantage
With 38 years of experience serving Maine communities, A Plus Roofing understands how ventilation design interacts with local weather patterns. Our team installs complete ventilation systems that protect your roof, reduce heating costs, and extend the life of your shingles.
Whether you’re replacing your roof or improving an existing one, proper airflow is your best defense against hidden damage.
Ready to make sure your attic is breathing right?
Contact A Plus Roofing today for a free ventilation inspection and expert guidance on optimizing your roof’s performance.