The attic is usually an ideal spot for collecting moisture, which can come from elsewhere in the home. Water vapor can drift up from showers, dishwashers, and other appliances and settle in the insulation and other areas such as rafters and trusses. Once in the roof sheathing, water often condenses and leads to various problems, and can also cause paint to peel, insulation to become saturated, and mold and mildew to grow. The various kinds of attic ventilation products can help to circulate fresh air through the space. These typically include fixed or static exhaust vents, those that fit the ridge shape of the roof, intake vents, as well as house fans.
Heated air can cause a number of problems in an attic, especially when it is combined with moisture. Exhaust vents generally remove moist air. Typically installed along the roofline under the shingles, ridge vents can be installed along the length of a roof, so the ventilation can be evenly distributed. The direction of the wind usually does not affect how the vent works, and it often provides a higher airflow volume than other attic ventilation products. While a power vent is fixed in one place, it can be most suitable for certain roof types and often has a thermostat to help control heat levels in the attic.
Static vents are often inexpensive, and roofing contractors usually have the experience to install them. Multiple vents, however, have to be installed in some cases, at equally spaced areas along the roof. Most of these attic ventilation products have a screen to prevent animals and contaminants from getting inside, while various styles include square, slanted, or dome shaped vents.
Another type of product to keep the attic space fresh is an intake vent, which can be installed under the roof shingles or within the eves. A balance of exhaust and intake attic ventilation products is generally recommended because this can help stop moisture and heat from building up, and prevent ice from forming in cold weather as well. They can also lessen the load on the air conditioning system. When used with a whole house fan, heat is usually drawn out more effectively and the costs of cooling the house are typically lower.
Solar-powered attic ventilation products are often available as well. The vents are typically located at the gable side of the house, while solar panels can be put anywhere there is enough sunlight to keep the system working. Operating the vent does not use any energy other than that produced by the solar panel.