TinnerFlow™4th YearRoof Curbs, Louvers & Exterior AirCheck first
High face velocity may need a storm/wind-driven-rain louver, not a basic weather grille. Verify the louver selection against airflow and rain performance requirements.
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Some louvers shed normal rain but cannot separate water at high intake velocity or severe wind exposure. If the face velocity is too high for the louver type, water can carry through into filters, plenums, and equipment.
Check face velocity, louver model, drainable blade design, filter/plenum water marks, and the submittal performance rating. The likely recovery is a correctly rated storm/wind-driven-rain louver, added moisture separation, or revised intake design by the engineer/detailer.
Use this as training guidance. Foreman direction, approved drawings, project specs, manufacturer instructions, employer safety policy, and AHJ/code requirements always control the final answer.