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Odd discovery in bathroom

I am in the process of adding a larger exhaust fan. I have had a problem with mildew and failing drywall joints, and hence the upgrade. As I am removing the ceiling (as to vent the fan through the roof, and not the wall) I noticed that underneath the drywall was a layer of Tyvek. The bathroom sits on the second floor - there is no attic space so above the bathroom ceiling is simply insulation and the roof.

Should the Tyvek be there in the first place? It is my understnading that Tyvek is not a vapor barrier, but a wind barrier. It is doing any harm by being there, that is by allowing vapor to enter into the insulation cavity? Should this be replaced with a 6 mil vapor barrier? I do intend to gut and remodel the BR at a later date.

Thanks for any insight.


Re: Odd discovery in bathroom

The closest I can come is to say that Typar is used for barriers when blown-in insulation is used. Don't know why they'd put Tyvek there. It's not likely to do any harm, anyway.

Re: Odd discovery in bathroom

If you live in an area that has cold winters then you would definately want the 6mil poly as a true vapour barrier.

I've never seen or heard of house wrap being used on the warm side of the insulation --- correction --- I've run into this when whomever had done a misguided reno and didn't understand or simply didn't know about the difference between an air barrier and vapour barrier.
Curious -- you mention a gut of the bathroom later --- is this because someone previously tried to do a half assed reno ?

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