b'STEEP SLOPEare extremely deteriorated. I chalk that up to the lack ofKey Point #2: It Must be Balancedattic ventilation. Balanced attic ventilation means an equal amount of As the seasons change during the year from warm tointake airflow at the soffit, eave or low on the roofs edge cold, moisture buildup inside the attic is the concern.combined with an equal amount of exhaust airflow at or The average family of four generates 2 to 4 gallons ofnear the roofs peak. Only when its balanced can the water vapor per day from cooking, cleaning, showering,system bring in cooler, dryer air through the intake vents doing laundry, running the dishwasher, breathing andto flush out any warm, moist air through the exhaust perspiration. In the winter months, this moisture isvents. When its balanced, the airflow can wash the attracted to the colder attic where it can condense andentire underside of the roof deckbottom to topacross eventually lead to wood rot, mildew, mold, poor indoorthe roof.air quality, and wet attic insulation that has reducedOne of the most common mistakes I see contributing to effectivenessif its not ventilated out of the attic properly. inefficient attic ventilation is lack of intake, Bellis says. The next level of proper attic ventilation is moisture.Many times, we identify that the exhaust is correct for Moisture is huge. A common problem is incorrectlythe size of the attic, but the intake is lacking. ducted bathroom fans into the attic, says Bellis. WeOn a project on a 100-degree day, Bellis measured make a point to emphasize this during our estimating,the attic temperature at 130 degreesabout 10 to 15 inspection process to differentiate ourselves in the eyesdegrees hotter than it should be if the attic has properly of homeowners. Bellis often finds wet insulation, rustedbalanced ventilation. The exhaust ventilation was fine, fasteners, and premature deteriorating roof decks. Onebut the vented soffit was not, he says. Bellis reported to sure sign of what Bellis calls a sick attic is rust spotsthe homeowner that he found solid wood underneath the on the insulation that have dripped from the nails above.vented soffit panel. In effect, there was no intake airflow.Those homeowners definitely have a sweaty attic; aWhile having a 50% intake and 50% exhaust attic moisture problem with the attic, he says. ventilation system is the goal, its OK to have more To help explain to homeowners the impact of proper atticintake than necessary. Excess intake turns into exhaust ventilation in the fight against ice dams, Bellis monitorson the leeward side of the house. But the reverse is not his own roof and attic. Hes created what almost amountsdesirable. Having more exhaust than can be supported to a testing lab over the years tinkering with the amountby intake is problematic. Heres why.of his attic ventilation and one-by-one fixing troubleExhaust vents (ridge vents, wind turbines, gable louvers spots. Each winter when his roof is snow-covered, heand box vents) that are starving for intake air can actually can see how it melts and compare it to other housespull from themselves (the back side of the vent in the on his street. Why do the other houses have ice dams,case of ridge vents) or from a nearby vent (in the case of but his roof does not? He uses that knowledge whenbox vents, wind turbines and gable louvers). Anytime an talking with his homeowner customers. exhaust vent brings in air it could also bring in weather, and thats a problem. They are designed to be exhaust.In the case of power attic fans (roof-mount or gable-mount), if they are lacking proper intake ventilation (based on the fans CFM rating; which is Cubit Feet of air moved per Minute) they could experience premature motor burnout, subpar performance and could actually pull air from the conditioned living space.Be sure the quantity of vented soffit is sufficient for the attic size and that the wood underneath the panel is actually open to the attic; photo courtesy of Epic Exteriors.Key Point #3: Ridge Vents are Most EfficientNo other category of attic exhaust vent combines the superior performance and good looks that a ridge vent system delivers. Of the five categories homeowners can Graphic shows balanced attic ventilation; photo courtesy of Air Vent, Inc. choosewind turbines, gable louvers, box vents, power attic fans and ridge ventsstrong consideration should Continued on page 30www.mrca.orgMidwest Roofer 29'