Poor Attic Ventilation? Look Out for These 4 Issues

Kristi Pahr
Written by Kristi Pahr
Updated December 16, 2021
neutral colored bedroom attic
Photo: Photographee.eu / Adobe Stock


  • Poor attic ventilation can cause roof damage via mold, mildew, and rot.

  • Ventilating attic spaces can help regulate temperatures in your living spaces.

  • Achieve ventilation through ridge vents and roof soffits.

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You may think of your attic as nothing more than a creepy, dark spot that may have spiders and bats, but a healthy attic is vital to a healthy home. A poorly ventilated attic can cause attic mold and mildew, ice damming, temperature fluctuations inside your home, and deterioration. Keeping it in tip-top shape is important.

4 Signs of Poor Attic Ventilation

How can you tell if your attic is properly ventilated? There are some easy-to-recognize signs.

1. Deterioration of Roofing Materials

A poorly or improperly ventilated attic can cause early degradation of your roof. Moisture accumulation in the attic can cause nails, flashing, and duct straps to rust, resulting in damaging leaks. Excessive moisture can also allow for the growth of mold and mildew beneath your shingles, causing them to rot.

2. Ice Dams

icicles on the side of house
Photo: Virynja / Adobe Stock

Ice dams are large pieces of ice that accumulate on the edge of a roof during winter. As heat seeps up into the attic space and warms the roof, snow melts and the resulting water runs down to the eave where it’s cooler, causing ice to form. This process continues throughout the winter, resulting in a significant buildup of ice that can damage roofing materials.

3. Mold Buildup

In a poorly ventilated attic, condensation can accumulate on trusses and the underside of the roof. This water drips down onto flooring or joists, and over time, causes mold, mildew, or rot to develop.

4. Extreme Heat

Since attics aren’t climate-controlled, they tend to get warmer than the rest of the home in the summer. In a properly ventilated attic, the temperature should mimic the outdoor temperature. A poorly ventilated attic traps heat and can warm up to 150 degrees Fahrenheit in some climates. That extreme heat is tough on roofing materials and can cause damage.

Problems Caused by Improper Attic Ventilation 

Though it may seem like a big empty space, your attic has needs. If those needs aren’t met, it can cause problems. Since attics are not climate-controlled, proper ventilation is a must to ensure moisture doesn’t accumulate, which can cause issues like mold, mildew, and roof damage. Poorly ventilated attic spaces can also affect temperature fluctuations in your home’s living spaces, causing excessive wear and tear on your heating and cooling equipment.

How to Improve Attic Ventilation

attic fan vent near chimney
Photo: knelson20 / Adobe Stock

If you suspect your attic has ventilation problems, the first step is to call a local roofing company for an inspection. Professional roofers will inspect the attic and roof for damage and discuss options for improving ventilation and repairing any existing damage. 

Roof repairs cost $300 to $1,600 on average. This cost will include labor, including repairing the leak and replacing and sealing shingles. If roofers find mold, you might need to contact a mold removal company near you as well. Mold remediation typically costs $1,000 to $7,000, depending on the severity and the size of the area impacted.

Improving attic ventilation will increase your roof's life span and help with heating and cooling costs by making the attic a less extreme environment.

Types of Attic Ventilation

There are two main categories of attic ventilation your roofing company can employ to improve your attic: natural and mechanical.

Natural Ventilation

Achieve natural ventilation by getting air to flow through the vents and fans in the roof and eaves. Ridge vents and soffit vents allow air to flow through the attic instead of being trapped. Wind turbines catch the wind and replace hot air inside the attic with cooler air from the wind.

Mechanical Ventilation

Mechanical ventilation is achieved with the use of electric fans attached to the roof. These fans constantly run, providing continuous fresh air to the attic space. These electric roof vents are ideal for homes with little to no wind exposure.

Both methods will increase the airflow through your attic and help to dispel any moisture buildup. Natural ventilation is the most common for homes, but if you live in an area without much wind and with high rainfall, you may want to talk to your pro about mechanical ventilation as well.

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