Is Mandated by Roofing Manufacturers & Local Building Codes
Validates Your Roofs Warranty
Automatically Increases Your Warranty from 0/25/30 Years to 50 Years
Saves Energy, Reduces Utility Bills & Landfill Costs
Cuts Your Long-Term Roofing Costs by 50%
According to the National Homebuilders Association (HBA) surveys the average roof is replaced between 17 and 19 years despite the average 25/30 shingle warranties.
All roofing manufacturers (CertainTeed, GAF, Owens Corning, Tamko, IKO & Sheriff-Goslin require proper ventilation be installed to validate their new shingles warranty.
Sadly, almost all roofers’ unknown to homeowners fail to install proper ventilation leaving them without an actual warranty.
Studies have proven that if you keep the air temperature just below the roof deck in your attic, including cathedral ceilings as cool and dry as the outside temperature new shingles should last up to 50 years more than twice as long as they last today.
Proper attic ventilation must be balanced between intake vents typically found at the roofs lowest point such as under the eave edges/soffit areas and exhaust vents at the ridge or as close to it as possible.
Here is an example of how to calculate the Net Free Area to be vented properly (we perform and disclose this calculation to each homeowner for their specific home):
Step 1: Measure the Attic Floor Area
• Calculate the attic’s floor space in square feet (length × width). Ignore sloped ceilings or irregular shapes unless specified by local codes; focus on the flat floor area under the roof.
• Example: 50 ft × 30 ft = 1,500 sq ft.
Step 2: Determine the Ventilation Ratio
• Use a ratio of 1:150 (1 sq ft of NFA per 150 sq ft of attic floor) if there’s no vapor retarder (barrier) installed on the warm side of the ceiling, or in humid climates.
Step 3: Calculate Total Net Free Area (NFA) Required
• Formula: Total NFA (sq ft) = Attic floor area (sq ft) ÷ Ratio
• Using 1:150: 1,500 ÷ 150 = 10 sq ft total NFA.
Convert to square inches if vent specs use that unit (1 sq ft = 144 sq in):
• For 1:150: 10 × 144 = 1,440 sq in total.
Step 4: Allocate for Balanced Intake and Exhaust
• Split the total NFA roughly 50/50 between intake (lower vents) and exhaust (upper vents) to promote airflow.
• Formula: Intake NFA = Total NFA × 0.5; Exhaust NFA = Total NFA × 0.5
• Example (1:150 ratio, sq ft): Intake = 10 × 0.5 = 5 sq ft; Exhaust = 5 sq ft.
Step 5: Select and Size Vents
• Choose vents based on their labeled NFA (not gross area, as louvers/screens reduce it).
• Example: If using soffit vents rated at 9 sq in NFA per linear foot, for 720 sq in intake: 720 ÷ 9 ≈ 80 linear feet of soffit venting needed.
• Factor in roof pitch, attic volume, or powered fans if passive ventilation isn’t sufficient. For steep roofs or large attics.
