Faced vs unfaced batts

[CxHxExVxY]

Looking to insulate and finish the inside of my shop. It has the bubble wrap style insulation (Astro armor) under the tin.

It will be studded out 16in oc and going to use r21 batts

So should I plan to use unfaced batts due to the possibility of faced batts causing a double vapor barrier or am I over thinking this and it doesn’t matter

Thanks

 

[billconner]

That answer is solely dependent on your climate. If primarily an air conditioning climate, just use unfaced. If primarily heating climate, I'd rip out the bubble wrap and use unfaced with a poly vapor barrier on inside. That's the general answer.

Floor and vapor barrier under it, how much moisture you produce in the garage, and how much to what temp you heat all might mitigate and allow changes to the general answer.

 

[CxHxExVxY]

Thank you.

I’m in Missouri,
Currently I just plan to heat it. It can easily get into the negatives during winter months here and I’m looking to keep the shop around 50-55* durning the winter. now down the road having AC sounds nice.

I have a 6 in floor with vapor barrier underneath and two insulated garage doors

 

[billconner]

First choice is still remove bubble wrap, install unfaced, and a poly vapor barrier. However, I suspect you can get away with just unfaced and a permeable interior wall. You don't seem to have a lot of moisture production inside. (Don't store firewood inside and no unvented combustion heating.) I think if there is some condensation on the bubble wrap, it will dry inward before it causes damage. Some risk, but not much IMHO.