It's Good to Vent... The Attic

Having adequate attic ventilation year round is important to the long-term health of your home, optimum interior comfort, and reduced heating and cooling costs. Here are a few tips.

Your home should be a respite of comfort even during the most humid months in Wisconsin. However, that can be challenging when one of the most common problems homeowners face is inadequate attic ventilation.  

Poor attic ventilation can make your home unbearably warm in the summer and cause damage to the roof (e.g. fatigue the sheathing) when moisture gets trapped. This will also increase your energy costs as your air conditioning is run more to dissipate the heat. Did you know that attic insulation stores up the day's heat and can increase the temperature of your interior ceilings to as much as 110 degrees.

Not Just a Summer Issue

It's still important to vent the attic even in the Winter.  Moisture from indoor activities will migrate from the living spaces to the attic. This can delaminate plywood and rot roof sheathing and framing, and cause mold or mildew to grow throughout the home.

What to Look For

Rusted nails and stained roof sheathing (boards) are the first signs of a ventilation problem.  Here's what to look for seasonally:

  • Winter - Moisture or frost on exposed nails at the underside of the roof sheathing.  Frost can loosen and push nails out.
  • Summer - On warm and windless days, there should be a maximum 10-15 degree difference between the air in the attic and a shady spot outside. 


  1. Clear any blocked soffit vents. This can often cure most ventilation problems.      
  2. If you don't have vents, install ridge and soffit vents to allow for natural airflow.  Cool air enters the soffits under the exterior roof overhangs and circulates the hot air via natural convection to a roof or gable-mounted low speed fan. 
  3. Have a Home Energy Audit performed. This will often illustrate hidden     problems while providing you with a plan of what areas to address first.

NOTE: During Summer operation, thethermostat will automatically operate the fans as needed to force air circulation.  

In the Winter, the fan should be operated by ahumidistat and attic should be kept cool to avoid ice dam issues.  

This post is contributed by a community member. The views expressed in this blog are those of the author and do not necessarily reflect those of Patch Media Corporation. Everyone is welcome to submit a post to Patch. If you'd like to post a blog, go here to get started.

Avenging Angel September 06, 2012 at 08:49 PM
Installing gabel vent fans was the best thing I've ever done. It lowered my cooling costs by 20%.
Scot McLean, Home Inspector September 08, 2012 at 01:24 AM
Hello Avenging, So your insulation in the attic [what there is of it] is not now 130-degrees in the attic all night next to the ceiling and keeping the A/C on all the time. You lowered the temp., perhaps just enough not the cook out your roofing materials, shorting its life expectancy. All good, aim towards trying to keeping the attic as the same temp as outside year-round! Best type of venting creates convection air movement.


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