Tell someone or document it before you close it up.
Louver connection not weatherproof/coordinated
A louver connection is also a wall/weather connection. Treat gaps, sleeves, screens, and seal methods as water-control and access issues, not just duct leakage.
Do not create a water path into the duct or block louver/screen access.
Check
Identify how the duct is supposed to connect to the louver: sleeve, collar, boot, flexible connection, or flange detail from the submittal or wall detail.
Look for visible gaps or daylight around the wall penetration and louver connection. Do not assume mastic is the correct fix for a wall/weather gap.
Confirm whether weatherproofing, firestopping, flashing, or wall sealant is your scope, the GC's scope, or another trade's scope before you seal or walk away.
Check that the louver screen or bird screen remains accessible and is not blocked by the duct connection.
Photograph the connection before closing the wall or insulating so the weatherproofing path can be reviewed if needed.
Steps
Identify how the duct is supposed to connect to the louver: sleeve, collar, boot, flexible connection, or flange detail from the submittal or wall detail.
Look for visible gaps or daylight around the wall penetration and louver connection. Do not assume mastic is the correct fix for a wall/weather gap.
Confirm whether weatherproofing, firestopping, flashing, or wall sealant is your scope, the GC's scope, or another trade's scope before you seal or walk away.
Check that the louver screen or bird screen remains accessible and is not blocked by the duct connection.
Photograph the connection before closing the wall or insulating so the weatherproofing path can be reviewed if needed.
Say this to your foreman
The louver connection at [location] has a [visible gap / no sleeve / unclear seal method / blocked screen]. I am not sure whether the weatherproofing at the wall is our scope or GC scope. Can you confirm before I seal or leave it?