Need some vapor barrier and insulation advice

[Woody65]

So, I built a 32x40x12 pole barn 6 yrs ago with no intention of heating it. I did not put any house wrap under the board and batten siding. I am preparing to stud the walls and use either rock wool or fiberglass insulation in the walls and blow in insulation in the ceiling. The interior walls will be made of galvanized corrugated metal for the bottom 4’ and ship lap wood for the top 8’. My question is should I put vapor barrier on the inside of the studs underneath the wall covering? My instinct tells me not to. It seems the warm air on the heated interior will meet the cold air in the wall and condensate. I could be wrong.

 

[Roadworthy]

Normally the vapor barrier on insulation goes toward the inside of the building. I would go with a vapor barrier if you plan to insulate and heat.

 

[Henro]

Normally the vapor barrier on insulation goes toward the inside of the building. I would go with a vapor barrier if you plan to insulate and heat.

Yes, the vapor barrier goes on the hot side. Since your inside is likely to be hotter than the outside, the vapor barrier should be on the inside.

I guess it is always a balance question. IF you are in a location where it is on average hotter on the outside, the vapor barrier position would be reversed...

BUT you are in NY...so vapor barrier goes on the inside...

Edit: Since you asked the question, it is assumed you are going to heat the space. IF not, probably does not matter and if it were me I would just forget about the vapor barrier...as well as insulation.

 

[Woody65]

Yes, the vapor barrier goes on the hot side. Since your inside is likely to be hotter than the outside, the vapor barrier should be on the inside.

I guess it is always a balance question. IF you are in a location where it is on average hotter on the outside, the vapor barrier position would be reversed...

BUT you are in NY...so vapor barrier goes on the inside...

Edit: Since you asked the question, it is assumed you are going to heat the space. IF not, probably does not matter and if it were me I would just forget about the vapor barrier...as well as insulation.

Thanks for the response. Yes, I will be heating the space.

 

[dlctcg]

I would use rock wool hands down over fiberglass insulation in the walls... & vapor barrier on the inside.

 

[toyotadriver]

A great vapor barrier AND more insulation would be to go with 1 inch foam boards on the inside and then tape the seams and then cover with whatever wall covering you want.

 

[fishdrivel]

Be sure and do the math on prices and R values.
1" foam is only r4 and you can get r13 fiberglass more cheaply. I'm not up on current prices.

My last major remodel I found I could get insulation installed cheaper than I could buy the materials.

 

[xrjohndeere]

So, I built a 32x40x12 pole barn 6 yrs ago with no intention of heating it. I did not put any house wrap under the board and batten siding. I am preparing to stud the walls and use either rock wool or fiberglass insulation in the walls and blow in insulation in the ceiling. The interior walls will be made of galvanized corrugated metal for the bottom 4’ and ship lap wood for the top 8’. My question is should I put vapor barrier on the inside of the studs underneath the wall covering? My instinct tells me not to. It seems the warm air on the heated interior will meet the cold air in the wall and condensate. I could be wrong.

Have someone come in and spray foam it. Spray foam will seal up the building and save you on heating and cooling.

 

[Have tractor did travel]

Rock wool advantage is sound control. A rock wool room is shockingly quieter (of outside noise) than a fiberglass insulated room. In a garage environment, sound control may be of no advantage to you - and purchase should be based on other factors - price, availability, ease of installation. The following from a study done on the Permeance of Steel Roof Decks and Effect on Hygrothermal Performance of Roofing Systems Joseph P. Piñon, PE Raymond W. LaTona, PhD, both members of ASHRAEA. "Although the field of the steel deck is impermeable, the side and end laps contain gaps that permit water vapor and air to pass through the deck."
What that means to you Woody, is you should absolutely NOT put a vapor barrier behind the metal sheathing. However, you should seal each piece of metal you install, so no air gets around the openings. The insulation purchased at HD will either be unfaced (no vapor barrier), or will have either a asphalt impregnated paper face (vapor barrier), or an aluminum face (good vapor barrier). You want the first one for insulation behind the metal.

You write " My instinct tells me not to. It seems the warm air on the heated interior will meet the cold air in the wall and condensate. I could be wrong."
Your statement related to condensation is correct, but that would mean you SHOULD vapor barrier - not go with your instinct 'not to". Maybe your fingers got confused.
You need to vapor barrier behind the ship lap, and keep any air from getting past the ship lap and down behind the corrugated metal at the bottom.

I like xrjohndeere's suggestion. But that won't be cheap. It's not typically a DIY job.

Good luck with it.
Eric

 

[Woody65]

Thanks for all the great info. I am currently running all the electric for the interior and exterior lights along with outlets. I might get a quote on the spray foam, closed cell I believe, and weigh the difference in cost. Thanks again and I will keep ya in loop.