Insulating My Pole Barn - need help

[JerryK]

Don't know about a vapor barrier. A pole barn has a lot of moisture in the winter with vehicles/tractors/people tracking in and out/etc. There is probably not many pole buildings that don't leak a little water thru their lifetime. The moisture has to go somewhere, so I would not try to make it too tight.. In my barn, when the roof has a foot of snow on it, the moisture forms as frost on the bottom side of the sheetmetal roof, then when the snow slides off, the frost melts and rains down a little onto the top of the foam panels. The only way you can stop that is to insulate directly onto the roof sheetmetal bottom. But you would still have to have a false ceiling insulated to keep the heat closer to the floor. The under the roof insulation would make it hard to locate leaks in the metal roof, if you ever got any. You can spray foam under the roof, but that isn't cheap either. You can get frost on the bare walls, too. But it does not take much of a barrier to keep that from happening. The foam or even a sheet of chipboard would probably stop that.

 

[steveessie]

I recently insulated and finished my pole barn. You didn't mention what you are doing with the ceiling, but the ceiling insulation is more important that the walls. I put a vapor barrier under the trusses, followed by metal liner plate, then blew over 6 inches of celllulose in the ceiling.

For the walls I bought some used polyiso (high performance foam insulation) from a roofing company and fit that into the walls. Styrofoam is not great insulation. If I had it do over and didn't have the polyiso available, I would put cellulose in the walls. Put tyvek or some other building wrap against the girts, put a vapor barrier over the inside of the poles, add drywall/OSB/Metal panels/etc on the inside, leaving a gap at the top that can be closed after blowing the cellulose into the wall cavity.

Cellulose is the most cost effective insulation out there and it's super easy to blow in.

I am in the process of making a drop ceiling at 9ft (originally ceiling is 15 feet - so there will be a space between the original ceiling and my drop ceiling). I studed between the joists for my ceiling and am in the process of laying kraft-faced fiberglass insulation R11 - it is cheap and will at least hold in some of the heat. I am more concerned about the walls and if I need a vapor barrier. I will use the polystyrene, simply because it is cheap and pretty hassle free. Do I need a vapor barrier with polystyrene?

Half of the garage is going to be uninsulated (30x30) where I park my cars, trucks, toys, etc. The "heated" part (the other 30x30 I am insulating) will be used for the kids to play in and to do regular vehicle maintenance when it is too cold in the winter.

So, do I still need a vapor barrier in the walls of the insulated part if I use polystyrene between drywall and metal?

 

[JerryK]

I would say no... you want the insulation and everything to breathe as much as possible.... You have a lot more moisture in that barn than a normal house... [ but, then again, I am just an old uninformed retired furt... ]

 

[KennyG]

I'm going to say use the vapor barrier. I've never seen an effective insulation system without a vapor barrier. The vapor barrier should go next to the heated space. I doubt you will get the styrofoam to ever seal well enough to form a barrier and that pretty well ruins the insulation value.

Being as far north as you are, condensation won't be much of a problem since the siding will be naturally ventilated anyway. I never saw condensation in my pole barn before I finished it. Be sure you have roof vents and a way to get air above the finished ceiling. In any event, I wouldn't put the foam directly against the metal because it won't be really against it. There will be all kinds of spaces to trap air/moisture.

I don't mean to start an argument (although that happens to me often) but I think you need to look carefully at the cost and results you will get. Cellulose almost has to be cheaper than styrofoam. I put about 6 inches of cellulose in my 40x48 pole barn attic for about $300.

How did you do the drop ceiling? I'm having trouble seeing this. How are the new joists supported?

 

[Murfster3]

I have a 32 x 40 pole barn that I installed a metal ceiling and I put blown in fiberglass insulation in the attic around 2'. The walls I installed a plastic vapor barrier then used blown in fiberglass insulation. The thing was I picked up bags of it at lowes in the summer for $9.99 a bag. It's usually priced at $30 something a bag plus you can use there machine for free. I have 2 vent free furnaces that heat it and it stays 50 degrees on the lowest setting

 

[steveessie]

I have a 32 x 40 pole barn that I installed a metal ceiling and I put blown in fiberglass insulation in the attic around 2'. The walls I installed a plastic vapor barrier then used blown in fiberglass insulation. The thing was I picked up bags of it at lowes in the summer for $9.99 a bag. It's usually priced at $30 something a bag plus you can use there machine for free. I have 2 vent free furnaces that heat it and it stays 50 degrees on the lowest setting

Did you install the vapor barrier closest to the metal or did you attach it against the framing you would hang drywall from? Which order was it:
metal, plastic, blown insulation, plastic, drywall (or OSB)
or
Metal, blown insulation, plastic, drywall (or OSB)

 

[Murfster3]

Did you install the vapor barrier closest to the metal or did you attach it against the framing you would hang drywall from? Which order was it:
metal, plastic, blown insulation, plastic, drywall (or OSB)
or
Metal, blown insulation, plastic, drywall (or OSB)

It was metal, insulation, plastic and then osb.

 

[Aquamoose]

I am very intrigued by the feedback left as I'm in a very similar position with my 36 x 48 shop. Thus far, I've got the ceiling covered with OSB and already have radiant floor heating in place but not hooked up yet. My plan was to blow in insulation at the top (nothing else up there) but with air dams/gaps at the ends to allow cold air in the attic space. Originally I was going to stuff "Brillo pads" (for the life of me, I don't know what else it's called) in the inside gaps at the bottom where the outside steel panels and the base caps meet to deter critters. My plan after that was to put up bat insulation but reading some of your comments, I'm surprised to see suggestions of cellulose as insulation as a cheaper alternate.

 

[Gunny]

I can't see how putting some Tyvek house wrap could hurt anything, since it would be a both a vapor barrier and cut down on air movement, but I don't think I would want cellulose up against the metal. I would think it wouldn't take too long for condensation to soak it through. Ideally, in that case, you would put the Tyvek wrap on first, but then you'd have to frame up a stud wall and cover that to be able to blow in the cellulose and that's getting expensive and a lot more work.
The house wrap could be stapled up then the Styrofoam placed directly over that and seal the seams with tape for more airflow control. I would also recommend that you at least cover the bottom 4 feet of Styrofoam with some OSB to keep from getting holes knocked in it.

Like said above, the ceiling is the most important thing to worry about when keeping heat in, the walls would be pretty much good to go with less insulation as long as you block the airflow.

 

[mehig]

I've seen insulation for use in metal pole building that looks like/is bubble wrap. You put it up first and then put the metal over it.