A single-skin louver blank-off panel sweats inside the wall

Single-skin metal can become a thermal bridge between outside air and conditioned space. Use the approved insulated blank-off/vapor-sealed detail to stop condensation.

Insulation, Liner & Vapor Barrier 2nd Year YELLOW

Watch out

Do not use uninsulated scrap sheet metal as an exterior louver blank-off in conditioned spaces.

Check

Look for sweating, staining, wet insulation, or wall cavity moisture.
Confirm whether the inactive louver section is exposed to outdoor temperature.
Check approved blank-off/insulation/vapor barrier detail.
Remove raw single-skin patch if it is causing condensation.
Seal edges so warm humid air cannot reach cold metal.

Steps

Look for sweating, staining, wet insulation, or wall cavity moisture.
Confirm whether the inactive louver section is exposed to outdoor temperature.
Check approved blank-off/insulation/vapor barrier detail.
Remove raw single-skin patch if it is causing condensation.
Seal edges so warm humid air cannot reach cold metal.

Say this to your foreman

The louver blank-off at [location] is sweating on the interior side. I checked for thermal bridge and air leakage. Do you want it replaced with an insulated sealed blank-off detail?

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