vapor retarder?

Ignore the random debris in the foreground, Is this an improper installation of moisture barrier? You can see the “foil” in the background that covers a lot of the attic.


I think you’re OK since you’re in Louisiana.

No The Barrier needs to go on the warm side of the insulation

Is the “foil” supposed to be a moisture/vapor barrier, or was it installed as a partial radiant barrier?

In Louisiana the warm side is out side.

In hot, humid climates, a Class I or II vapor control layer on the interior of the framing can, and often does, cause premature building enclosure failure due to inward moisture drive condensation (see RR-9302: Humidity Control in the Humid South). BSC recommends avoiding Class I or II vapor control layer on the interior in these zones, or any material that acts inadvertently like a Class I or II vapor control layer such as reflective foil insulations, vinyl wall coverings, glass mirrors and epoxy paints.

If it was installed as a vapor retarder, it should be OK where it is since Louisiana is in Climate Zone 2. If it’s installed as a radiant barrier, it is usually applied over the rafters or trusses and under the roof decking.