House wrap or 6 mil poly?

[383 240z]

I'm ready to start the wainscoting on my build. I have tons of 6 mil poly available to me. Would this be OK to use instead of house wrap? I'm not going to spray foam the building (unless I hit the lottery soon) but i still would like something between the steel and the posts and stringers.

The plan for the interior is foam panels for insulation in the walls with plywood for wall coverings. Blown in insulation, metal roofing for the ceiling, with a metal roof.

Good idea or bad idea?

 

[RPH]

House wrap, you want it to breathe. It allows the moisture to vent but stops water intrusion.

 

[mike93lx]

Those are very different materials. Use house wrap. It's the right tool for the job

 

[billconner]

Housewrap if you are in a heating climate.

 

[kbs2244]

house wrap on the outside, under the siding
poly on the inside, under the paneling

 

[marak]

Perm rating of 6 mil poly is 0.06.

Perm rating of house wrap is at least 5.0, per International Code Council.

Perm rating is a measure of the amount of water vapor transmitted through an area of material. Interior and exterior paints have different perm ratings because they have a different function regarding vapor movement.

 

[billconner]

All true in a heating climate. If you're in south and plan to air condition, poly on outside.

 

[383 240z]

I figured it wouldn't work. I was just hoping I could save a few bucks. I have to put a new engine in my truck and scope creep got ahold of me.

 

[rburke65]

Wrap.

 

[u2slow]

Tar-paper. It met Code for my shop build in 2013. (Heating climate)

I don't like house wrap because a shop building is rarely kept warm enough to turn liquid into vapour for the 'breathing' to work.

 

[jack stand]

I can't see much in the picture, but that left (hillside) worries me (a lot) . Do you have plans to get the runoff around the building and continuing downhill?

 

[firebirdparts]

I think poly on the inside and nothing on the outside is the only reasonable option for using poly. Water will not be "trapped" in that scenario. Whether or not you like that option of nothing outside is another question.

Practically everybody in the south has bubble wrap or vinyl faced insulation on the outside, so it's not apparently critical to avoid that either. Nobody building garages worries about it. FWIW. They could all be idiots, I don't know.

 

[u2slow]

Metal siding will condensate on the backside, so you want something behind it to prevent lumber and sheathing from getting wet.