With nearly 10 inches of snow across many parts of Illinois this week, you can learn a LOT about your attic’s ventilation just by looking at your roof. If some areas of your roof are already melted while neighboring spots still have thick snow, it’s a red flag:

🔥 You have hot spots in the attic.This means heat is being trapped where it shouldn’t be—and your attic isn’t breathing properly.

Good attic ventilation isn’t optional. It directly impacts the life of your roof, the health of your home, and even your energy bills. Below is everything Illinois homeowners need to know, especially during heavy winter weather.

Patchy snow melt like this means the attic isn’t breathing properly—heat is trapped and escaping through the roof.

❄️ The Goal: Attic Temperature = Outside Temperature

A properly ventilated attic should stay close to the outdoor temperature—even in extreme cold.

When your attic runs too warm:

• Snow melts unevenly

• Moisture gets trapped

• Ice dams form

• Shingles deteriorate faster

If the roof looks patchy with melted spots, your attic is acting like a heated room (which it should NOT be).

🔁 Intake + Exhaust: How Air Should Flow in Your Attic

Your attic needs balanced ventilation. That means:

✔ Cold air IN through intake vents (soffits)

✔ Warm air OUT through exhaust vents (ridge or roof vents)

If either side is blocked, undersized, or mixed incorrectly, the whole system fails.

🚫 Do NOT Mix Exhaust Vent Types

This is one of the most common mistakes we see in Illinois homes.

You cannot combine:

• Ridge vents + box vents

• Ridge vents + power fans

• Power fans + box vents

• Power fans + ridge vents

When mixed, one vent becomes an intake, sucking in snow, moisture, and unconditioned air from the other vent—creating pressure problems and short-circuiting airflow.

Choose one system, size it correctly, and let it work the way it’s designed.

🚫 Do NOT Block Intake Vents

Soffit vents must stay open and unobstructed for your attic to breathe.

But many homes suffer from:

• Insulation pushed too far into the soffits

• Painter’s caulk or paint sealing vents

• Vinyl/wood soffits with clogged perforations

• Bird or insect nests

  
  

If soffit vents are blocked, your exhaust vents become useless—air can’t escape if fresh air can’t enter.

Baffles (rafter vents) should always be installed so insulation doesn’t stop airflow from entering the attic.

🏠 Poor Ventilation Shortens Roof Life

Your shingles are designed to last 25–50 years depending on the product. But without proper ventilation?

They can fail in 10–15 years.

Symptoms include:

• Blistering shingles

• Premature granule loss

• Curling edges

• “Dry-rotted” appearance

• Hot attic temps (sometimes 130–160°F in summer)

Manufacturers like GAF, Owens Corning, and CertainTeed all require proper ventilation for warranties to stay valid.

Learn more about our roofing services here:

👉 https://www.restorewithcornerstone.com/asphalt-roofing

🦠 Bad Ventilation Causes Mold Growth

Warm, trapped air rises and gets stuck in the attic. In winter, that warm air meets the cold roof deck and turns into condensation.

This creates perfect conditions for mold:

• Dark

• Damp

• Humid

• Poor air movement

Left untreated, mold spreads to the entire attic, insulation, and even down interior walls.

We see this constantly after cold spells or heavy snowfall.

❄️ Ventilation Problems = Ice Dams & Winter Damage

When heat leaks into your attic and warms the roof deck, snow melts. The water runs down to the colder edges and refreezes—creating an ice dam.

Ice dams cause:

• Interior leaks

• Wet insulation

• Sagging ceilings

• Roof rot

• Fascia and gutter damage

Proper ventilation + insulation reduces this risk dramatically.

Ice dams often lead to roof leaks, deck rot, and gutter damage. If you’re already dealing with winter issues, or you suspect your gutters aren’t performing well, this becomes a bigger problem.

Explore gutter replacement and repair options:

👉https://www.restorewithcornerstone.com/gutters-and-downspouts

🛁 Bathroom Fans Should Never Vent Into the Attic

A huge problem in Illinois homes.

Bathroom fans push warm, moisture-heavy air into the attic. If they’re not ducted through the roof or gable properly, this causes:

• Mold

• Condensation

• Wood rot

• Wet insulation

All bathroom exhaust ducts should be:

• Insulated

• Air-sealed

• Terminated outside the home

🌬️ Humidity Control Matters Too

Attic ventilation can’t fix indoor humidity problems alone.

Ideal indoor humidity in winter should be 30–40%.

Too much moisture raises:

• Condensation

• Frost on roof decks

• Mold risk

• Ice dam formation

Dehumidifiers, sealed bypass humidifiers, and fixing air leaks help control interior moisture.

🔍 How to Tell If Your Attic Has Ventilation Problems

Look for these signs:

• Uneven snow melt on your roof

• Ice dams forming

• Frosted nails (“frosting”)

• Mold on the sheathing or insulation

• Musty smell in the attic

• Excessive heat upstairs

• High energy bills

• Shingles aging too fast

If you’re already seeing uneven melting from this snowstorm, that’s your first clue.

🛠️ How Cornerstone Restoration Fixes Attic Ventilation Issues

We provide full attic evaluations to identify:

• Blocked soffits

• Incorrect or mixed exhaust vents

• Wet or moldy insulation

• Bathroom vent issues

• Undersized ventilation

• Improper exhaust vent installations

Then we build a balanced plan:

• Proper intake (soffit) ventilation

• Correctly sized ridge or roof exhaust vents

• Unblocked airflow channels

• Insulation & baffles where needed

• Moisture control recommendations

A well-ventilated attic protects your roof, your home, and your health.

🔚 Final Thoughts

Attic ventilation is one of the most overlooked parts of a home—but also one of the most important. With our heavy snowfall this week, roofs are already showing clear signs of heat loss and improper airflow.

If you’re seeing uneven melting, ice dams, or have concerns about the health of your attic, now is the perfect time to get it inspected.