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Thread: Attic Venting

  1. #1
    Join Date
    Jun 2008
    Location
    Chattanooga, TN
    Posts
    1

    Default Attic Venting

    have a 40-year one and one-half story house. The front soffit is covered with dental molding so there are no soffit vents. The roof's pitch is steep and high. The seconded floor is dormered on the back and there are a five slotted grill vents in the dormer leading to the top attic. The attic venting consists of five sheet metal vents on the backside of the steeply pitched roof as well as one thermostatically controlled fan (Broan) which I replaced last year when I moved in b/c is wasn't working. I am fairly certain that there in inadequate venting in my attic. (To be more confused, I'm now hearing about houses that are not vented but rather insulated with foam). I think my roof decking and shingles are being cooked. My question is should I have a ridge vent added (I'm not getting up there) or add gable-end vents and possibly a larger, louvered thermostatically controlled attic fan on one gable end. Thanks.

  2. #2
    Join Date
    Aug 2007
    Posts
    443

    Default Re: Attic Venting

    Try to keep the attic below 100 degrees if possible---permanently install a thermometer up there & check it on hot days thru the attic opening with a flashlight.

    A ridge vent is an excellent idea & should be tried first---being at the top of the attic it's where the hottest air accumulates--since it is passive, it burns no electricity.

    There has to be an equal number of openings to let air in at the lower sections of the attic near the eaves/soffits so there will be a constant flow of air from bottom to top.

    Since you indicate you want someone to do the job, why not call several roofing contractors & see what they say is the best way to vent the attic.

    Solar fans are becoming very popular these days & are now dropping in price---these would also be a big savings on electricity.

    Some people put in much larger 3-speed attic exhaust fans which serve the double purpose of cooling the occupied floor immediatealy below the attic, especially overnight & on cooler days---this saves a lot on AC costs in the summer.

    Google "attic ventilation", "ventilating the attic" "attic exhaust fans", etc. to get many articles on this topic.
    Last edited by JacktheShack; 06-26-2008 at 07:24 PM.

  3. #3
    Join Date
    Aug 2008
    Posts
    54

    Default Re: Attic Venting

    Ridge venting is not bad. It gives you 180 square inches net free vent area per 10 feet of ridge vent, but I often question that having been in some extremely hot attics with ridge venting. To determine how much venting you need, divide the square footage by 300 then multiply the answer by 144 for all high venting, (roof vents or ridge vent) or divide by 600 and multiply by 144 for high/low venting. (roof vents combined with gable or soffit vents). A lot of people don't know how important proper venting is. If your attic is not adiquately vented, your insulation will not do all the job it is supposed to, and you can end up with rotted decking from moisture trapped in the attic. VERY IMPORTANT - vent exhaust fans out of the attic through dedicated roof vents and wrap the pipes with R-11 duct wrap to prevent condensation problems. Venting these out gable, soffit or ridge vents will rot the decking or soffit/facia. I've seen this happen a lot.

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