Understanding Attic Ventilation is essential if you own a home in MN

It can be a confusing topic; first you insulate your home to stay comfortable and reduce utility bills, but then you have vents installed in your attic that let the warm air out, even in the dead of winter. What’s up with that?

The principles of science come to the rescue!

A sealed attic will trap excessive heat and moisture, causing extreme heat buildup on the roofs surface, which can in turn lead to reduced shingle life. Worst yet, the heat buildup is not just a summer concern. In the winter, hot air trapped in the attic can melt snow on the roof during the day, and then refreeze at night, creating ice dams that lead to interior leaking and roof damage

summer and winter ventilation

In the summer, heat buildup in the attic can encourage premature aging and cracking in wood and other roofing materials. Unwanted heat can also transfer into living areas, making it uncomfortable and reducing energy efficiency.

In the winter, warm air generated by activities such as laundry, showers, dish washing and cooking can cause moisture buildup in the attic.

How is a homeowner supposed to keep their cool?

You need to make sure that your home has the proper attic ventilation to help prevent damage and premature aging, caused by excess heat buildup in the summer and moisture in the winter.

In order to create a consistent flow of cool, dry air through your attic, you need to make sure the air has a way to come in and go out: intake and exhaust. For a roof, intake is usually achieved through eave or soffit vents, while exhaust is achieved through roof vents or ridge vents. It’s critical to have the correct balance between the intake and exhaust vents to ensure air flows constantly and efficiently.

attic ventilation diagram

Without proper ventilation, everyday household activities can wreak havoc on a roofing system. The general rule of thumb is to have at least one square foot of vent space for every 150 square feet of attic area. If there’s a vapor barrier beneath the insulation, it can be 1/300. The most effective solution is a system of continuous ridge-and-soffit vents which provide balanced ventilation, which also helps your roofing shingles last longer.

Proper attic ventilation offers all these benefits:

  • It allows outside air to flow naturally upward and out of attic.
  • It promotes a cool, dry attic.
  • It helps minimize the impact of ice damming.
  • It helps prevent moisture from becoming trapped in insulation, structural wood, shingles and roof deck
  • It helps prevent rotting, mildew, drywall damage, peeling paint and warped siding.
  • It provides year-round performance for consistent ventilation without energy consumption.

What about finished attics?

The answer is rafter venting. Rafter vents, or insulation baffles, install in any rafter space to create narrow gaps that direct fresh air from the soffit vents to the peak of the roof. These specialty vents do not affect the finished look inside the remodeled attic. Instead, fresh air still flows in through the soffit vents and travels along the underside of the sheathing until it reaches a ridge vent or can be vented with another type of exhaust vent.

Have unanswered questions? Call Gunner Insulation at (763) 355-5460

We are happy to answer any questions you might have. We can also explain how your roof, attic ventilation and insulation can all work together to create a more energy efficient and comfortable home, plus you can avoid future ice dams.