Benefits of Proper Attic Ventilation

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Properly installing a roof involves much more than putting on the shingles. Whether it’s in warm or cold climates, proper attic ventilation plays a key role in helping to make the roof system last longer and prevent many expensive issues from occurring inside and out of a building. Contractors should explain to homeowners why proper attic ventilation is so important with the benefits below. It serves two key functions:

  •  Allows cool, fresh air to enter the attic at the eave or soffit areas of the roof
  • Exhausts hot, moist air from the attic by way of the ridge or other exhaust vents. This hot, moist air can cause a whole host of issues.

In cold climates, ventilation helps maintain a “cold” roof system by mixing cool outside air with attic air to allow for less snow melting on the roof, therefore avoiding damaging ice damming. In warm climates, proper attic ventilation helps expel hot air, which can contributes to moisture problems.

Here are some benefits of proper ventilation:

  • It helps reduce damaging moisture. Excessive moisture can build up in the attic, potentially damaging the structure and degrading the roof system. It can also lead to mold.
  • It can help save energy. Heat build-up in that attic comes at a cost—a home’s air conditioning has to work harder to cool down the house, especially the living space below the attic.
  • It helps prevent damage to the roof shingles. High attic heat can bake the shingle and cause them to prematurely age. In fact, most major shingle manufacturers strongly recommend proper attic ventilation on asphalt shingle installations.

Unfortunately, most homes in North America are improperly ventilated, which can result in mold, wasted energy, ice dams, premature roof system degradation, rotting decks, peeling paint, and ceiling stains.

The best way to keep a roof system working well and to help avoid the issues mentioned above is to install proper attic ventilation. Proper attic ventilation creates a balanced system using ridge vents or other exhaust vent in conjunction with intake vents installed at the eave, soffit, or fascia area of the roof. Intake ventilation is critical in ensuring the exhaust vents function properly. Without intake ventilation, most ridge or other exhaust vents can be rendered virtually useless.

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  1. Angel Pineda

    Liza, Great article

    Articles like this help both homeowners and contractors in their business. One this I would like to add is to check for bathroom and kitchen vents. I often see these are vented into soffits and moisture and warm air get back into attic space.

    • Thomas J Taylor, PhD

      Thanks for checking our blog. Yes – other vents should definitely not be venting into or near soffit vents. You make a great point that this should be checked during any survey such as a new home survey or before reroofing.

  2. vivek

    Roof ventilation needs to be ideal all through the year. The lack of roof ventilation in summer makes the roof to act as a huge radiator, radiating the trapped heat back thus increasing the temperature and energy bills

    In winter the lack of roof ventilation will see the build of moisture within the roof space leading to a number of problems occurring. Sufficient roof ventilation such as a whirlybird will ensure; Mould will not build up, insulation will stay dry and damp free avoiding any damage to the roof structure. Statistics shows that homes without a whirlybird or other form of ventilation are paying 40% more than those who have sufficient ventilation such as a whirly bird installed.

  3. Irvine

    I have to say a very thorough article. May I just add one more benefit for the sake of the topic?
    As someone, who has done this professionally for many years now I can make a small addition – it is super beneficial to guttering systems as well. Those ice dams are literally devastating to whatever gutters you have, only the most costly ones can withstand them to be honest. Water expanding volume when freezing could cause disjoint and whatnot to your rain gutters! Things are connected – well insulated or ventilated roof results in healthy gutters with time.

    Thank you, just wanted to point that out as well. Very well done, keep the good work up, Liza!

    Regards, Irvine H.

  4. Camille Guerrier

    Thank you for sharing the benefits of proper attic ventilation. We just moved into a house with an attic and have decided to store some of our important things up there. We wanted to insulate the attic because it will be worth it in the end. Like you said, “it allows cool, fresh air to enter the attic and exhausts hot, moist air. This could become a problem because we live in a very hot climate during the summer. Thank you again!

  5. John Broccoli

    Hi Liza, I am about to insulate the underside of my roof with sprayfoam insulation. The attic is finished space and the insulation will be at least R-38. I was told that I don’t need to vent in this case since there will be no hot or cold air transfer due to the insulation. Is this true? Thanks, John

    • Liza Barth

      Hi John,
      Typically, when sprayfoam insulation is utilized, it completely seals-in the attic space which essentially makes it part of the living space or additional conditioned space. Thus, attic ventilation would not be part of this system. We’d recommend you contact the sprayfoam installer for their recommended system for any additional details. Thanks! Liza

  6. greg

    Liza ,thank you , i install cellulose insulation and lay radiant barrier over the insulation and staple to the wood floor in attics. I sometimes have the home owner know it all telling me to insulate the attic rafters or that i have to put the radiant barrier on the rafters. I tell them in is unnecessary to staple to the rafters unless your in Arizona where it would make sense since it’s hot all the time. Also ,in Memphis, TN, you want to trap the heat in the house, this year is a prime ex. I save alot of money by insulating and laying radiant barrier over the insulation.

    • Greg Bublitz

      Solar attic ventilation can be a good solution for some projects. If solar powered ventilation is installed in a difficult to ventilate situation (i.e. unbalanced with no soffit venting, or complex architecture) the result can be that the make up air is drawn from the conditioned living space through air bypasses. This means that AC costs and heating costs go up. Hardly a zero operating cost or green option then. Better to make sure air sealing is done first, then proper insulation, then venting. Without the first two, the venting option becomes less effective.

  7. Mary Kaschak

    If a home has ridge vents installed during a re-roofing but the attic has the interior roof covered in fiberglass insulation, does this prevent the ridge vent from working properly. I see floors of attics always insulated but in all of your photos, the interior roof of the attic never is. What is the proper insulation, if any, for an interior attic roof (pitched) in southern New Mexico?

    • Liza Barth

      Hi Mary,
      It’s generally recommended that only the attic floor be insulated properly when using a through attic ventilation system consisting of ridge and intake ventilation. Insulation at the attic ceiling can impede the airflow from the intake source from traveling up the underside of the roof deck and reaching the ridge. It may also absorb any moisture that traveled up from the living space into the attic and cause issues. Thus, we recommend insulating the attic floor when attic venting is used.

    • Liza Barth

      Hi Gordon,

      We have a full line of Master Flow Green Machine Solar Powered and Dual-Powered ventilation products.They’re a great options for folks who want to cool their attic without the related utility costs or hard-to-schedule/expensive electricians.

      For areas where ventilation is needed at night or in cloudy weather, we have solar vents with patented dual-power technology which allows the vent to switch automatically between solar and house power for 24/7.

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