b'Airflow Test Methods Show Major Differences in Ridge Vent Products* Ridge vents were tested to determine the opening area that would allow the same airflo~ Vent Used Above chart depicts square inches NFA per linearofvent footridge Shingle Over Ridge Vent with 30 Maze Nails & Snow FilterBasedonIndependent LabReponofwith1-800-320-6031 testing equipment built to ASHRAEIAMCA 210 parameters. CalculaUons and test protocolbased onwww.headrick.net wereASHRAE Fundamentals, AMCAIASHRAE 210 and916. AldCAIHVI'