TinnerFlow™2nd YearRoof Curbs, Louvers & Exterior AirStop / get direction
Exterior louver blades and drainage paths are directional. If the louver catches rain, stop and reset it to the approved orientation before the wall is closed or weather hits.
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A storm or intake louver is not just a grille. The blade slope, sill, gutter path, and weep holes are built to shed water outward. If the frame is upside down, the blades can act like little troughs and send rain into the mechanical room or wall cavity.
Confirm the manufacturer airflow/weather side, blade slope, sill location, and weep path. The normal recovery is to remove the fasteners, pull the louver, rotate it to the correct orientation, reseal the perimeter, and verify the weep holes are open before the exterior trade covers anything.
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.