Page Title Poor Attic Ventilation Can Ruin Your Insulation,
Destroy Your Shingles, And Raise Your Energy Bills!
Why Take Risks? It is estimated that 9 out of 10 homes in North America do not have proper attic ventilation. Why? Because most people are unaware that attic ventilation can impact the longevity of their entire home! For example, in the summer, an improperly ventilated attic can cause heat to build in excess of 160°F. This superheated air eventually penetrates the ceiling insulation into the living area below. Types of damage that can
result include: - Premature aging of your roofing system (“fried” shingles)
- Warping, cracking, or breaking down of wood framing
- Damage to siding, exterior or interior paint, and wallpaper
- Higher energy costs
A properly ventilated attic can help reduce the load on your air conditioner by moving the superheated air out of your attic before it builds up and causes damage.
In the winter, various household appliances, bathtubs, showers, and cooking vapors can contribute to excess moisture build-up. Improperly ventilated attics will allow this moisture to collect and cling to the underside of the roof. There, it will condense and fall, soaking the attic insulation and reducing its efficiency Additional structural damage
can include: - Roof deck warping and rotting of the wood frame
- Mildew growth
- Buckling of shingles and felt
Finally, attics should be properly ventilated to help prevent ice dams in cold northern climates. During the winter, ice and snow on a roof will melt and run down the deck to the cooler eaves. This run-off can re-freeze, creating an ice dam that will trap moisture on the roof. The moisture can eventually back up under the shingles and enter your home — causing hundreds or thousands of dollars of damage to your ceilings and walls. Adequate attic ventilation will reduce the amount of initial melting that occurs on your roof, thereby reducing the chance that ice dams will form. | Proper Attic Ventilation Proper attic ventilation systems allow a continuous flow of outside air through the attic (see illustration at left), protecting the efficiency of the insulation and helping to lower temperatures in the living space. It consists of a balance between air intake
(at your eaves or soffits) and air exhaust
(at or near your roof ridge). The FHA (Federal Housing Administration) recommends a minimum of at least 1 square foot of attic ventilation (both intake and exhaust) for every 300 square feet of attic space. For example, if your attic is 900 square feet, you need a total of 3 square feet of ventilation. This amount is generally divided equally between intake and exhaust ventilation (i.e., 11/2 feet of each), to insure proper air flow through the attic. To calculate the amount of ventilation you need for your home, follow the example shown on the next page. |  | GAF Cobra® Exhaust Vent
For Roof Ridge Protect Your Roof From Premature Deterioration By Providing Effective Attic Exhaust Ventilation << Back to Attic Ventilation Effective attic ventilation is critical
for a long-lasting roof! A properly balanced attic ventilation system will help to: - Remove excess heat and moisture to protect your roof from premature deterioration
- Prevent roof rot in your attic or roof deck
- Minimize peeling and extend the life of exterior and interior paint
- Limit the growth of harmful mold
- Safeguard your attic possessions against mildew damage
- Guard against ice damming in harsh winter climates
- Possibly reduce excessive heating and air conditioning costs
 Cobra® exhaust vent is a key part of the GAF-Elk Smart Choice® Roof System Solution, and has even earned the prestigious Good Housekeeping Seal Homeowner’s Best Choice - Vents Your Attic…
Allows heat and condensation to escape at the most effective location—the ridge.
- Looks Terrific…
100% shingle-over design is virtually invisible when installed.
- Superior Protection…
Helps to prevent wood rot and extends the life of your exterior paint.
- Safeguards Possessions…
Helps limit mildew growth caused by damp attic air.
- Energy Efficient…
May even reduce your utility bills!
- Weatherproof…
Passes 110 mph wind-driven rain and snow infiltration tests.*
- Safer…
Helps prevent problems with insects, birds, and animals in your attic.
- Peace Of Mind…
Backed by a 40-year ltd. warranty.** *Under controlled laboratory conditions. **See ltd. warranty for complete coverage and restrictions. Professional’s Best Choice - Greater Homeowner Satisfaction…
Low-profile design is hidden by ridge cap shingles.
- Easy To Install…
Quick, 3-step process; no need for complicated fitting, wrapping, connectors, or end plugs.
- Nails Included…
Smart Nails™ for hand-nailing, or 1 3/4" coil nails for nail guns, ensure consistent installation.
- Superior Performance…
Net free ventilating area:
- Cobra® Hand Nail: 16.9 sq. in./linear foot
- Cobra® Nail Gun: 14.1 sq. in./linear foot
- More Reliable…
Will not crack or dent during shipping or installation; won’t corrode, rust, or turn brittle.
- Cap Shingle Compatible…
Works with traditional size ridge cap shingles.
- Two Sizes…
Available in 20' & 50' rolls. Balanced Ventilation Requirements Balanced ventilation requires an equal amount of intake ventilation and exhaust ventilation. GAF-Elk recommends, at a minimum, providing 1 square foot of Net Free Ventilation for every 300 square feet of attic floor space. Consult local building codes for specific ventilation requirements in your area. - Calculate the total square footage of the attic floor area (round up to the next highest number). This number will determine the minimum total linear feet of Cobra® exhaust vent that is needed.
- Find the appropriate amount of Cobra® exhaust vent and minimum intake ventilation that corresponds to the total attic square footage.
| Based on 1/300 Rule | Total
Attic Square
Footage | Recommended Length of Cobra® Exhaust
Vent (Feet)* | Minimum Intake Ventilation (Net Free Area in Sq. In.)* | | 1600 | 23/28 | 389/395 | | 1900 | 27/33 | 457/466 | | 2200 | 32/38 | 541/536 | | 2500 | 36/43 | 609/607 | | 2800 | 40/48 | 676/677 | | 3100 | 45/53 | 761/748 | | 3400 | 49/58 | 829/818 | *First figure pertains to hand nail, second figure pertains to nail gun. NOTE: Always have a balanced ventilation system. In no case should the amount of exhaust ventilation at the ridge exceed the amount of soffit ventilation. << Back to Attic Ventilation | |  |
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Class A Rated |  Approval # NOA 03-1110.02 | Florida Building Code FL197-R2 | | Cobra® Hand Nail: | YES | YES | YES | | Cobra® Nail Gun: | YES | YES | YES | | | | | | |  | |
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