Vapor Barrier for Conditioned Attic
jthayer
| Posted in General Questions on
I have a 1918 bungalow and am doing a full remodel of the finished attic including the addition of a shower. I have not changed the roof venting but doubled the R value with R30 mineral wool (unfaced). There are gable vents and a fan, but no ridge vents.
I live in upstate NY (zone 5). I assumed I needed a vapor barrier but the Building Code officer said that I don’t. That seems odd to me, especially with the addition of a shower. Does anyone have any advice?
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Replies
Yes you do. Typically this is achieved with poly (true vapour barrier) or one of the more modern vapour retarders. Some will use a vapour barrier latex paint.
Either there was a miscommunication between yourself and the BO or he is confused.
To be clear, there is no vapour impermeable layer in the wall and ceiling already?
I would make sure at this stage that the rafter bays and attic have sufficient ventilation. With no ridge vent the gable vents will need to be large enough, and placed high enough, to ventilate the small attic space above the collar ties.
Thank you. It seems odd to me when the BO said one wasn't necessary. And yes, there is no vapor impermeable barrier in the wall nor ceiling.
There are rafter vents in every bay under the insulation, and the gable vents in each end are what they are. I have the gable vent on a thermometer and a switch and plan to have it on often.