Attic covered with plastic

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I was inspecting this home in North Dakota and came across this attic covered in black plastic. I believe from what I can see that the underside of the roof has been sprayed with foam insulation. I also believe that the house had a fire in it at one time and has been rebuilt. My concern is will this black plastic cause issues with moisture since it can not breathe. Thanks. GDS

Open cell or closed cell foam, behind the black plastic?

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Do I see a Gable vent? That would be unusual to vent an attic with spray foam decking.

That being said, did you see any evidence of problems?

Class I vapor retarder should not cause issues with moisture when the roof was insulated, that open plumbing stack however is another story.


Thanks for the reply. I did call out the vent stack. As far as any issues I couldn’t see anything as they were pretty good at covering everything with plastic.
The other concern is are they trying to cover something up.

I know, I hate that. What can you do other than state your limitations?

I’m thinking that with open gables, the spray foam insulation and plastic is nothing more than a radiant barrier.

Shingles have very little permeability, add in the foam and plastic and it is zero. Condensation might be an issue, maybe.


Thanks for your help. I really appreciate it.

I see you are in ND where temps have been sub-zero. Is that frost on the plastic, or just dust?

It is just dust. It was actually about 15 below 0 when I inspected this. Was mostly concerned about condensation in the summer time. Thanks


Any idea what the electrical wiring goes to in the first picture?

No I could not tell. I did call out the fact it should have a cover on it.

In addition to condensation, a small roof leak’s moisture damage will likely increase both in size and duration when the moisture is effectively trapped in the space between the plastic and roofing membrane.

That is a good point. I will pass that information along. Thanks

That non standard installation, imo, has no practical application. If someone can think of a possible benefit of the black plastic let me know. I can think of a few, really negative, downsides.

I have seen a small attic space that had been covered in (clear) plastic. The incorrect thinking was that it would make the space below warmer. The whole area became moldy, and this was in a semi arid area. I have also seen a similar situation that facilitated a rodent infestation.

Personally, and professionally, I would recommend removal of all that attic plastic, and it be re-inspected before closing.


Thanks I will pass this along to the client.