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THE EVERYTHING FIX-IT BOOK
Exhaust ducts from bathrooms and kitchens in cold-climate attics should be insulated to prevent condensation from forming inside the ducts and dripping back down into the bathroom or kitchen. It’s especially important that these ducts exhaust to the outside, rather than simply ending in the attic. They’re designed to remove moist air from the house; pumping that air into the attic will cause condensation problems. Your attic may have a combination of vents, including soffit vents in the underside of the area where the roof overhangs the house walls, gable vents that are up in the peak of the house wall just under the roof, ridge vents that run along the peak of the roof, or roof vents cut into the roof itself. All of these vents should be kept clear (insulation, for example, shouldn’t cover soffit vents) and should be screened off so that insects, birds, and animals can’t get through them. You also need to make sure that you have adequate ventilation. There should be about 1 square foot of venting for every 300 square feet of attic floor space, assuming that there’s a vapor barrier in place; if there’s no vapor barrier, aim for 1 square foot of ventilation for every 150 square feet of attic space, but keep in mind that power- or wind-assisted roof vents will reduce the ventilation square footage needed. In cold climates, vapor barriers—usually sturdy 6-millimeter plastic films—should be placed against the warm side of the house (the attic floor, for example). The insulation itself should be adequate for your climate; check local building codes, but look for a total attic R-value of about 38 for most areas. It should also be dry and evenly distributed. Insulation should be kept at least 3 inches away from any heat-producing item, such as electrical or light fixtures (unless they’re rated IC, which means that insulation can be placed near them), or chimneys.
Beware of Attic Contents Although attics can seem like a great place to store unused items, they’re not. Especially if they’re unfinished and unheated/uncooled, they’re exposed to temperature extremes and to water damage from roof leaks, all of which can prematurely deteriorate paper and wood items. Stacks or boxes of paper and clothes are perfect homes for unwelcome guests such as mice. Flammable or explosive items such as pressurized 206