Need vapor barrer in pole barn?

[sixdogs]

I am insulating my 42X60 Mrton bldg with batt fiberglass in side walls and blown-in 30" fiberglass in ceiling. Lined with 29 ga indoor steel. Heated with propane a couple months a year. Have concrete floor with vapor barrier under it.

The Amish guys that are doing it say I don't need plastic on the walls and ceiling but I think Morton suggests it. Some say just the ceiling. I'm confused and just want this to be an easy job.

I don't know if it's that big a deal or not but I figure someone here would know and suggest what I should do. Any help or advice appreciated. Thank you.

 

[framer]

Not a big fan of vapor barriers on inside of heated buildings. warm air meets
cold condensates in the walls. Have some law suits going on in ks. now.
Framer

 

[srs]

I am insulating my 42X60 Mrton bldg

The Amish guys that are doing it say I don't need plastic on the walls and ceiling but I think Morton suggests it.

I don't know if it's that big a deal or not but I figure someone here would know and suggest what I should do. Any help or advice appreciated. Thank you.

Sixdogs, Have you contacted Morton to see what they say? Like I mentioned to you in an earlier post my salesman gave me a copies of their installation guide regarding insulation and they are very specific about using plastic as a vapor barrier. They specifically address sealing any and all holes in the plastic. Give your salesman or Morton headquarters a call and see what they say. Better to do that now then to be sorry later on. Let me know. Good luck!

 

[anojones]

I'm not sure there is a perfect answer to this question. If the outside of the building is metal any moisture that forms inside due to heating will move through the wall and insulation and condense on cold metal- if the metal is in contact with the insulation the insulation will get wet. Probably the best way to avoid that is the have an airspace between the batts and the outside wall that is open at the top of the wall into the vented attic. The problem with metal is that the moisture can't escape as vapor to the outside, unlike other siding materials. Your post mentions inside metal walls-the metal is a vapor barrier unlike sheetrock/OSB which would allow vapor to pass through, and the question is should you add another one between the metal and the fiberglass. If you do add a plastic vapor barrier any moisture that gets past the metal will condense on the plastic and may be trapped against the metal, but at least won't get into the insulation and will likely be able to re-enter the room at some point when you are not heating it. The real key is probably ventilation in these types of scenarios, so any moisture that does form can get out.

 

[sixdogs]

SRS--read anojones post and you can understand my confusion. I believe anojones understands the situation correctly and I am leaning towards his suggestion. I have called Morton but don't like to bother them since I am not buying from them. They gave me a confusing answer.

 

[theboman]

I'd check Morton on thier recommendations. I know they have some kind-o warranty, and for their prices you're paying for it, so don't loose it. I'd think they have to tell you what is not acceptable, and there's the anti-trust laws out there they have to observe in what they tell you.

 

[Luremaker]

Not a big fan of vapor barriers on inside of heated buildings. warm air meets
cold condensates in the walls. Have some law suits going on in ks. now.
Framer

In cold climates a vapour barrier is mandatory. Without a vapour barrier you will get condensation in the wall where you do not want it. The vapour barrier will keep your insulation nice and dry. Wet insulation isn't worth a darn. Now you must place the vapor barrier on the inside (warm side) of the insulation and seal it completely. This way any condensation (if it ever happens) is away from the insulation and framing materials. Now if you have a problem with moisture in your building all you need is a simple air exchanger. I'll post back later with a few pictures of my shop being built with the insulation and vaopur barrier installed.

 

[sixdogs]

Luremaker

Do you suppose south central Ohis is a cold climate?

 

[theboman]

Luremaker

Do you suppose south central Ohis is a cold climate?

The inbetween world... You guys are a bit colder than we are in northeast KY.

I'd ask the ag folks, builders what's the frostline.

 

[rdln]

Not buying your insulation from morton? where else would you get it in that custom width?