Company Profile

Right here, in this section. Most of the information that follows will answer your technical questions. Also, I recommend you visit the resource links provided here on my website. In addition, when you receive a Corey & Corey Roofing quote, you receive much of this information in the folder with the quote. An educated customer is my best friend.

Building codes give minimum attic ventilation requirements. Most attics require more. Research suggests you need 1 square foot of ventilation space, or net free area, for every 150 square feet of attic floor space. Net free area is the total unobstructed area through which air can enter or exhaust a non-powered vent. If your vents are split between ridge vents and intake vents, the minimum requirement is also 1 square foot of ventilation or net free area for every 300 square feet of attic floor space.

A balance of intake and exhaust airflow through the attic is the best way to create effective, year-round ventilation. Thus, in addition to installing ridge vents, which act as exhaust vents, be sure your attic has intake vents in the soffit/eaves. To ensure a balanced ventilation system, match the amount of net free area the ridge vent provides with as much, or more, intake area. To do so, measure the length of ridge vent you will be installing, then double that length for continuous soffit vents because the net free area (NFA) of the soffit vent is 9″ and the NFA of the ridge vent is 18″.

Air Vent ridge vents feature an advanced designed, external baffle that is one of the keys to the ridge vent’s outstanding performance. The baffle deflects wind up and over the vent, creating an area of low pressure above the vent openings that causes lift. This is called the Bernoulli Effect. It’s the same effect that causes airplane wings to lift. This low pressure works to pull air out of the attic. The baffle also deflects wind over the vent to help prevent wind-blown rain and snow from entering the attic.

With an unbaffled ridge vent; wind, rain, and snow can blow directly in through the ridge vent. Air entering the vent can create pressure which prevents air and moisture from being pulled out. Also, stronger winds can actually pass through one side of the vent and out the other, which also prevents air and moisture from escaping the attic. Tests show that externally baffled vents outperform unbaffled ridge vents.

Air Vent’s internal weather filter provides a complete barrier from the elements. Wind-driven rain, snow, dust, and insects are trapped by the filter. And because Air Vent ridge vents provide continuous airflow along the entire roof, the internal weather filter is cleaned by the flow of air coming out of the attic. Only Air Vent has an internal weather filter.

Ice dams are barriers to water runoff on the roof. They usually form at the roof edge, just above the gutter, in cold, snowy climates. They form when snow melting on warmer areas of the roof, usually near the ridge, runs down and refreezes at colder roof overhangs. Warm spots on the roof are caused by the heat that escapes from the living space into the attic. Once this cycle of melting and refreezing begins, a barrier is formed, trapping the snowmelt and allowing it to flow up and under shingles. As the water begins to penetrate sheathing, insulation, wall cavities, and sheetrock or plaster then paint can begin peeling on outside walls and causing interior ceiling, walls, wallpaper staining and sheetrock damage. Homeowners usually blame their gutters, since that’s where the problem appears to be. But newer, wider, deeper gutters won’t solve the problem. Nor will add layers of insulation alone. What will solve it is adequate ventilation combined with proper levels of insulation.

The key to solving ice dams is to create a cold roof, with the temperature of the inside roof sheathing near that of the outside air temperature. To create such a condition, large volumes of outside air must enter at soffit intakes, sweep along ridge rafters, then exit at vents near the ridge. To prevent trapping warm air in the attic, an equal balance must be established between intake and exhaust air volumes. Since such a ventilation system is bringing cold air into an attic, the insulation must minimize heat loss on the attic floor. As an added precaution, use waterproofing shingle underlayment. It provides a waterproof-barrier beneath roof shingles that pooled water from melting ice dams and driven rain cannot penetrate. Our preferred underlayment is ALPHA PRO TECH-SUL.

Air exchange is a system of air intake and exhaust that occurs with effective air circulation. When stale, overheated air in your home or attic is vented out and fresh air is pulled in to replace it, that’s air exchange. In an attic, for example, cool air enters intake vents, which are located along the eaves. It’s warmed, then rises out of the roof ridge vents to expel heat. COREY AND COREY recommend SMART SOFFIT VENT which provides 9 inches of Net Free Area for each side-18″ total. AIR VENT SHINGLE VENT II provides 18 inches of Net Free Area. See the Comparison of Air Flow with GAF Cobra Ridge Vent installed properly. I have never seen it installed anywhere close to properly. Most installations have it reduced to 2″ or less Net Free Area.

Then compare Water Leakage Chart with other vents. The 0’s on Shingle Vent II should allow you to sleep at night. Maximum Air Movement with NOT even a drop in the bucket of Rain or Snow.