Why install a barrier like this in the attic?

1991 house. The attic insulation was totally sealed with a foil barrier. Besides limiting my inspection what are the ramifications?

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Moisture can get trapped from the living space, between and inside the insulation, and cause damage.

If you study building science, they’ll tell you that the air/vapor barrier should be against the warm side,
with insulation ABOVE that, to prevent moisture from being trapped in between.

There’s some info from ORNL.

And from Linas link…

Important Non-Energy Considerations

     **Potential for moisture condensation**

Condensation can be a concern when a radiant barrier is installed on the attic floor directly on top of conventional insulation. During cold weather, water vapor from the interior of a house may move into the attic. In most cases, this water vapor will not cause any problem because attic ventilation will carry excess vapor away. But, during cold weather, a radiant barrier on top of the insulation could cause water vapor to condense and even freeze on the barrier’s underside. A radiant barrier used in the attic floor application must therefore allow water vapor to pass through it. Some allow water vapor passage through holes or perforations, while others are naturally permeable. Some testing has been performed to determine the potential for moisture condensation with perforated radiant barriers laid on top of the insulation. A test was conducted during the winter in Climate Zone 4, using houses that were operated at much higher-than-normal indoor relative humidities. Since this testing did not reveal any significant moisture condensation problems, it is expected that moisture condensation will not be a problem in warmer climates

Location matters.

I would say after 20 years like this, it would be obvious how it was performing by inspecting an area.
If it was original that is.

Thanks guys. I’ve seen barriers on the roof, but not hermetically sealed on top of the insulation. A 1st for me.

Joe, hermetically?

Maybe it will keep the mold “fresh”…

Joking. :stuck_out_tongue:

But it was tightly sealed with a foil tape.

very dangerous situation, i saw a attic like this before with in 3 years the strapping and the bottom of the truss was completely rot, i was being called because a part of the ceiling ad fall down
i had to remove everything re-frame the bottom of the truss, new strapping, new vapor barrier at the right place, drywall and insulation

tell your client about this

Interesting Thanks Gus …for the info…Roy

It looks like it might have been from a grow-op they want to keep they moisture and heat in and don’t care about the structure. You didn’t see some weird holes or repairs near the panel did you? Or maybe a couple of places that look like a vent used to go outside and was sealed up?