"Sandwitched" Vapor Retarders In Attic Insulation

[Michael Thomas]

Chicago climate, unconditioned attic, two layers of batt FG insulation - both installed with the vapor retarder toward conditioned space - and 6"-8" inches of blown-in FG insulation added above the batt insulation.

Ductwork - but not furnace or air handler - is located in attic, no evidence of damage at ceilings below.

Of course I'll report it and recommend correction.

But I'm curious if has anyone has actually seen a problem as a result of this (as opposed to a reversed VR underfloor in crawl spaces, were I frequently see water damage as a result), and if so if you have a picture?

Thanks.

[A.D. Miller]

Chicago climate, unconditioned attic, two layers of batt FG insulation - both installed with the vapor retarder toward conditioned space - and 6"-8" inches of blown-in FG insulation added above the batt insulation.

Ductwork - but not furnace or air handler - is located in attic, no evidence of damage at ceilings below.

Of course I'll report it and recommend correction.

But I'm curious if has anyone has actually seen a problem as a result of this (as opposed to a reversed VR underfloor in crawl spaces, were I frequently see water damage as a result), and if so if you have a picture?

Thanks.

MT: I have seen this often as well as folks who install faced batts atop blown-in material. I suggest (1) removal and replacement with unfaced or (2) using a razor knive to make multiple slices in the facing.

[neal lewis]

Nope, never seen a problem as a result installing insulation the way you describe.