Attic Ventilation – Application Guideline

Do not install the insulation in an attic space unless satisfactory and stable ventilation is installed.
Acceptable cross-ventilation shall be preserved above all attic insulation by giving both low and high vents and gable end vents where possible. One square foot of net-free vent area (NFA) shall be provided for every 300 ft2 of attic area with 50 to 60% of the vent area located near the roof ridge and 40 to 50% located near the eaves. One level of venting can be used provided that sufficient cross ventilation can be maintained. When high ventilation is the last option, One square foot of net-free vent area (NFA) shall be provided for every 150 ft2 of attic area.
- Note: Though the window vents usage is permitted, the vents need to be permanently fixed and fulfill the minimum requirements for free vent area as stated above.
Ventilation should be enhanced wherever possible and useful to fulfill present code requirements once the attic insulation is installed. The types of vents and where they can be practically installed on each specific house differs. Consideration for choosing the type and location of vents is based on how much cross ventilation can be possible for the specific application based on the prevalent conditions and retrofit options.

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