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Apprentice answer

Why does a large exterior louver bank need a sill pan flashing

3rd YearRoof Curbs, Louvers & Exterior AirStop / get direction

Large louver banks need a managed base water path. Do not set them on raw concrete without the approved pan/flashing/end-dam detail.

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Plain-English answer

Big louver banks can take real rain load. The bottom of the opening needs a way to collect and direct water back out. Raw concrete can absorb water and let it migrate into the wall or penthouse.

Before final setting, check the sill pan, end dams, drip edge, bed sealant, and weep path. If the pan is missing, hold the install and coordinate a proper metal sill pan or envelope detail before anchoring the frames permanently.

Ask Foreman

The louver bank at [location] is sitting on raw concrete with no visible sill pan. I checked the base and drainage path. Do you want a sill pan/end-dam flashing detail installed before final anchoring?

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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.

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