Proper Attic Ventilation - Let The Air Flow!!

Proper Attic Ventilation for your attic

VIRTUALLY All HOMES ARE UNDERVENTILATED, EVEN NEW HOMES. Proper Attic Ventilation is usually not a top priority for builders. Unfortunately the average homeowner assumes it's OK and therefore it remains a "hidden" problem in most houses. Attic Ventilation Problems & Mistakes.

Ideally, there would be no difference between the OUTSIDE air temperature and the air temperature INSIDE your attic.

Attic ventilation is the process of air flowing through your attic. In order to fully understand proper attic ventilation we must first understand a couple of basic rules.

Rule #1 - Hot Air Rises - Pretty basic. Hot air tends to rise to the highest available point.

Rule #2 - In Order for Air to "Flow" it must be unrestricted. How does this apply to your attic? In order for the Hot Air to move OUT, it must be replaced by other air moving IN. This is called "make-up air".

Attic Ventilation Systems
Most homes use what is called a Soffit-Ridge System. This system has two parts: Intake Vents & Exhaust Vents. Was your home originally built with a Wood Roof Problems

Intake Vents - Called Soffit Vents -The rectangular vents (about 8"x16") under the eaves and around the perimeter of your home.

Exhaust Vents - Several Types: Wind Turbines (or whirlybirds) are the most common, electric or solar powered fans are also popular but not recommended. In addition, some houses have Static Vents for attic ventilation (basically a hole with a rain-proof cover). Finally, Ridge Vents are the newest type of vents.

What's The Best Attic Ventilation? - Generally either wind turbines or ridge vent. The problem is that many homes today have a hip style roof and do not provide enough ridge for ridge vent. The other thing is that all ridge vents ARE NOT created equal. Some provide almost no airflow. You must use a baffled ridge vent to effectively ventilate with ridge vent. Wind turbines work very well and the quality are much better today. The don't squeak like they used to. Go with the 14" wind turbine instead of the 12" wind turbine. It will pull 37% more air. In fact, two 14" wind turbines will pull as much air as an electric fan with an 8 mph wind. Whirlybird Website

How much attic ventilation do I need? - For proper and balanced attic ventilation, you should have almost one soffit vent for every 100 square feet of attic space. For example: a 2600 square ft. one-story house plus an attached two car garage will have about 3000 total square ft of attic space. You should have between 25-30 soffit vents on a home this size. A less exact estimate is about one soffit vent every six to eight feet under the eaves. These, combined with adequate exhaust ventilation will make a significant difference in the temperature inside your attic.

Watch this video from MichaelHoligan.com regarding ventilation.

 
How Does Attic Ventilation Work?
Back to our "Rules". As the sun heats up your roof, the air inside your attic will heat up. This hot air will tend to rise and naturally push up and exit through the exhaust vents. However, this can ONLY happen if air can enter to replace the exiting air (make-up air). This is what the Intake Vents (soffit vents) are for. They allow cool fresh air to enter the attic and replace the exiting air. This natural process keeps the air moving and helps flush out the hot air which contributes excessive heat gain in ductwork causing more energy use.

Virtually ALL Houses are Under-Ventilated or Improperly Ventilated.
Many houses don't even meet the minimum required by building codes. Not only does this result in increased heat gain in the house, but improper attic ventilation voids most roof warranties and causes premature aging of roofs and A/C units.

Improperly ventilated attics are another common problem. With regards to exhaust ventilation MORE is not always BETTER. Attic Ventilation Problems & Mistakes.

The Importance of Year-Round Attic Ventilation.
Proper attic ventilation also helps reduce the potential of dangerous mold and mildew from developing in the attic. During cool weather, moisture from the living space can condensate inside the attic if not properly ventilated. This creates an environment that can lead to mold, mildew and wood rot. Not only can this cause damage to your home, it can also be dangerous to your health. Proper attic ventilation will keep your attic dry and safe.

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