I am putting in a metal ceiling, where/how does the vapor barrier go?

[johneic]

It is going in my 1,500 sq ft pole barn that has central heat/air via a gas pack. The metal will be attached to the bottom of the trusses. I will blow in cellulose insulation afterwards. I plan to use heavy/thick plastic, visqueen. I see two options but maybe there are other ways?

1) Simply lay the plastic on top of the trusses

2) Staple the plastic to the bottom of the trusses

3) Other ways/material/methods?

The problem I see with laying it on top is getting tight fitment against the angled upright portions of the trusses. Stapling it to the bottom will of course leave thousands of tiny holes (but maybe mostly sealed up enough?).

I only plan to run the heat or air about 8 or less hours a day, I may leave it at a moderate temperature overnight.

Not sure if this is important but I currently have an enclosed R11 insulated shop inside heated by a hydronic system and cooled by a window AC. It has a six foot ceiling, barn has a 10 foot ceiling. I have insulated garage doors on each end. I usually spend seven days a week out there.

John

I suppose I should take pics? Will post some within two hours,

 

[oosik]

John - with your comments #1 & #2 - pictures would sure help. You are working on a shop built INSIDE a 1500 sq ft pole barn??

 

[johneic]

Above pic is the trusses facing west

Above pic is the North restroom/small office

Above pic is the Hydronic control system that heats the enclosed north and south areas

Above pic is the south enclosed area from the main part of the barn.

 

[TnAndy]

I'd go the simple route and staple to the bottom of the trusses. Plastic is normally used for a vapor barrier, installed on the warm side. Since you plan on metal on the ceiling, that is also a nearly perfect vapor barrier, except for the seams, the plastic is sorta redundant.

 

[johneic]

John - with your comments #1 & #2 - pictures would sure help. You are working on a shop built INSIDE a 1500 sq ft pole barn??

Actually the insulated shop is complete, I am now hanging the ceiling in the main part of the barn. Pics have been attached, I use the area above the six foot tall shop for much needed storage.

 

[johneic]

I'd go the simple route and staple to the bottom of the trusses. Plastic is normally used for a vapor barrier, installed on the warm side. Since you plan on metal on the ceiling, that is also a nearly perfect vapor barrier, except for the seams, the plastic is sorta redundant.

So I could skip the plastic?

 

[johneic]

I might add that I have worked in an office my whole life, ever since my First Sergeant told me I was going to work in his office at 17 years old. If you see any flaws in my past designs/pictures it is because I did the best I could with the skills I had. I also live on a fixed income now so money has been a limiting factor at times.

 

[johneic]

In case you are wondering what I do out there:

Here is Grandmother, Daughter and Granddaughter

One of Grandmother's sons after a day of blind retrieves

The Daughter in the first pic

Another one of my pups I bred

 

[Gary Fowler]

Regardless of the plastic location, I would be claustrophobic in a room with a 6 foot ceiling, but then I am almost 6 feet tall so maybe that isn't an issue for you.
I would say that the plastic is on the warm side just like the moisture barrier as applied to wall insulation.

 

[teejk01]

So I could skip the plastic?

I wouldn't. Plastic should minimize condensation from forming on the steel on the cold side of your ceiling.