Ben writes again from Great Falls, Virginia: "Refering to the Soffit/Ridge Vent FAQ: What commercial or manufacturer's standard(s) should a homeowner use in determining if he has enough air movement in his attic? Case in Point: If you are planning to install a new roof, does the roof manaufacturers, e.g., CertainTeed or GAF, have standards for air movement? Do you know what they are for CertainTeed or GAF? Does this override the Owens standard for air movement in the attic? - different flow rate or what? Why install the Owens Corning Pink Roof Vents, if the assumption is that you install wide enough soffits air will automatically enter and go to the top of the ridge vent - is this really true???? Please remember most folks allow the contractor to make those 2by2 holes in the wood soffits not realizing that may not even meet any std(s) at all to move enough air to meet Owens or CertainTeed or GAF std(s) – bye bye effectiveness and warranty!"

Answer: Owens Corning follows the HUD requirements pasted below. The companies you mentioned are competitors and I don't have information about the standards they use. We also have a calculator on line that may help you. http://www.owenscorning.com/around/ventilation/determining.asp

HUD Requirements for Proper Ventilation.
Ref: MPS 403-3

The following US Department of Housing and Urban Development Statutes covering the ventilation of structural space furnish a basic guide for determining proper ventilation styles and sizes for any home. These statutes appear in the latest edition of the "Minimum Property Standards."

The Correct Amount of Roof Ventilation:
As a general rule, one square foot of net free vent area per 300 square a feet of attic floor or area to be vented is recommended.

In the rare situation where no vapor retarder is used and proper distribution of undereave and ridge vents cannot be achieved, one square foot of net free vent area should be provided for each 150 square feet of attic floor or area to be vented.

For a balanced system, ventilation should be equal at the undereave and ridge. In cases where a balanced system cannot be achieved, always provide more than 50% of the total required ventilation at the undereave and the remainder at the upper portion of the roof.

Openings: All openings greater than 1/8 inch must be screened to prevent insect penetration and louvered to protect against the entrance of rain and snow.