4mm or 6mm vapor barrier?

[weatherby460]

Should I get 4mm or 6mm plastic for walls when putting insulation in a pole shed. It will be metal, then r19 insulation, then plastic, then metal wall liner for the walls.

Do I need plastic when installing cellulose insulation in the ceiling? I will be using the metal liner material also for the ceiling. thanks

 

[theoldwizard1]

The unit of measure is a "mil" or 0.001 inch.

4mm = 0.157" ; 6mm =0.236"

 

[zmaxmotorsports]

The unit of measure is a "mil" or 0.001 inch.

4mm = 0.157" ; 6mm =0.236"

 

[BruceMc]

4 mil is kind of flimsy when installing, so 6 mil is probably the most common install. Some even prefer to go with 10 mil.

 

[James-W]

I would think the thicker the better, well, within reason anyway.

 

[sands35]

Metal is already vapor impermeable. Probably easier to just caulk the seams?

Given that you are in WI, I'd think you'd want the inside of the wall to breath so moisture doesn't collect inside the wall. I.e., kraft faced insulation, wall board and latex paint. If you are worried about knocking it with mechanical damage, then perhaps ply "wainscoting" around the bottom 4'?

 

[HemiRamOn22s]

i use the 6 mil on the roof. I would suggest skipping the batt insulation and do 2" of closed cell spray foam on the walls. Then you wont need a vapor barrier on either side.

You dont need plastic on the ceiling as long as you wait to blow in the insulation after the ceiling is on.