Which Ventilator to Choose

In order to prevent problems due to frost, ice forming on the roof, water leakage that causes ceiling damage etc., we provide the following information to help you choose the right ventilator for your needs.

Model 301
Model 303
Model 302
Total ventilation capacity spread over: 12 openings 8 openings 4 openings
Net ventilation area: 144 sq. inches 105 sq. inches 96 sq. inches
Average evacuation flow: 418 cfm 266 cfm 134 cfm
Roof area ventilated per unit: 1000 to 1200 square feet ** 700 to 800 square feet ** 400 to 500 square feet **
Adjustable flashing: for slopes varying between 2/12 to 15/12 for slopes varying between 2/12 to 15/12 for slopes varying between 2/12 to 15/12
Minimum height: 20 inches 18 inches 15 1/2 inches
Standard colour: brown, black or grey brown, black or grey brown, black or grey
  • ** Soffits must be well-ventilated; air circulation in soffits must be unobstructed by insulation.
  • ** Attic insulation should have a minimum rating of R-30.
  • ** Access door to the attic should be well-insulated.
  • ** Air evacuation ducts should not discharge into the attic.
  • ** Any openings other than Maximum Ventilators or the soffits must be completely sealed.
  • ** Choose the Maximum Ventilator best-suited for your home according to the manufacturer’s recommendations. (See chart above)
  • ** The specifications, mentioned above, do not apply for cathedral roofs, metal roofs or roofs with restricted attic space.


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