Well - designed roof vents will help keep your home cooler and reduce you summer cooling costs. They also prevent the formation of ice dams and condensation in the winter, prolonging the life of asphalt shingles. With inadequate venting, warm and moist winter air escaping through the insulation will condensate in the frigid attic air. This condensation can build up on wood surfaces in the attic causing water damage, wood rot, and mildew. A properly balanced air circulation system requires 1 sq. ft. of venting for every 150 sq. ft. of attic space. If there a vapor barrier is installed, that need changes to 1 in 300 sq. ft. Good roof ventilation is easy to install, and inexpensive.
There are a number of attic vent combinations. Ridge roof vents allow air to flow from the soffits out through the roof peak. A turbine vent will draw air up through the roof. The rising hot air turns the turbines, drawing out even more air. Fixed grilles allow the air to pass through louvers and a number of power fans.
Continuous ridge vents are a new development in roofing. They allow the natural flow of air along the rafters to and the wind outside to create enough negative pressure to draw air out of the attic. This is the most energy efficient way to exchange attic air. The ridge vent covers a slit that runs along the roof. The opening is capped with screening and a small plastic roof to keep precipitation from entering the attic.
They are installed by removing the capping shingles from the ridge to expose the felt underneath. Cut away the felt 3 inches from the top to expose the sheathing. Draw a chalk line 2 inches from the top of the roof on both sides. Using a circular saw that is set to the exact depth of the sheathing, cut out the section of the roof. The ridge vent will attach with caulking and roofing nails.
For soffits, there are three basic configurations. These configurations are round, rectangular, and perforated. The round variety, called plug vents, is easy to install with an electric drill and an auger bit. The rectangular type requires the use of a circular saw. When cutting an overhanging section of roof, it is easier and safer to use a drill than an upside down circular saw. Continuous perforated soffits are manufactured and can be easily installed once the old soffits have been taken out, eliminating the need for cutting through plywood.
When you have chosen how to vent your soffits, inspect the area between the ceiling joists to make sure insulation is not getting in the way of the air flow. Blown insulation is more likely to cause this problem because it is loose and tends to drift. To keep blown insulation from blocking the soffits, construct a barrier to separate the ceiling from the soffit area. Use rigid material and cut them to fit in between the joists. Fiber glass insulation can just be pulled back or tucked under.
Roof vents reduce attic air temperatures and increase the efficiency of your home cooling system. Even in moderate climates, attic temperatures can soar. Remember that the floor of an attic is the ceiling of the living space below. Even with insulation, heat can radiate down into the living areas making the air conditioner work much harder to keep the space cool. They also serve to carry out moisture that can be produced from house hold chores like cooking and washing. A good roof ventilation system will keep you house cooler and protect the attic from mold, mildew, and wood rot.