Insultation in Pole Building

[bookman51]

I had a pole building (72'x40') built two year ago. I had insulation through out all the ceiling and insultation in the walls over the concrete slab for the shop (40' x 36'). I think it is about an R-7 with a white vapor barrier to the inside.

Now I am thinking of putting up drywall and pegboard around the shop area. Is it worth while to put up more insultation on the walls before I dry wall them? I think there is room for 6" batt insulation.

If so, do I have to do anything about the existing vapor barrier? Or, can I just put up more insultation and another vapor barrier on the inside side of it?

I am in Nebraska where the winters can get cold. I probably will be doing electric heat (radiant) and I will be using the shop only occasionally ...I am retired and will be doing retirement projects in the building as the mood strike me!



Thanks in advance.

Bookman

 

[GSSFC]

Double vapor barriers are a no-no! You want to move the vapor barrier to the warm side of the insulation.

 

[anojones]

Probably not a bad idea to add insulation. The problem is warm air holds more moisture and will move thru the wall and hit the existing vapor barrier and condese to water, making your added insulation wet. There are some ways to deal with this- add insulation without a another vapor barrier which would allow for the moisture that forms to move back and forth between the room, add insulation but make dead air space between the two layers of insulation. You could also add insulation and put a very good vapor barrier over the new insulation (thick plastic) with the goal being to not allow any moisture to be able to leave the room and into the insulation to condense on the old vapor barrier. The situation you describe is not really any different than a pole barn with metal siding- the siding is a vapor barrier, as moisture moves from the inside it will condense on the siding. I had that situation and chose to deal with it by adding a "complete" vapor barrier to the warm side of the room- I'm sure some moisture gets in, but I'm hoping not enough to do too much damage.

 

[bookman51]

Thank, I am leaning toward adding a complete vapor barrier (heavy plastic) to prevent any vapor from moving. I suppose I could get batt insulation without any vapor barrier and then add the heavy plastic on the inside so no vapor moves into the walls. Still looking for ideas.

Thanks

Bookman

 

[Dragster Racer]

I have considered going without a vapor barrier, and use enclosed insulation. But then the wood and siding are exposed to the moisture. I really think the best way is to go with a good vapor barrier on the inside. I thought about putting house wrap up first, then insulate, then vb. Would cut air infiltration, but allow moisture out. Anybody done this?

 

[Bob Burr]

This seemed like a more appropriate place for this post -- so please excuse the repeat post (earlier I posted same question in General section).

I am about to insulate my pole barn building. My building has 6 inch poles, is framed out with 6 inch wood, is wrapped on the outside, and is sided with wood on the outside. We will be insulating the walls with R-19 fiberglas with a Kraft backing placed to the inside.

My question is: after installing the insulation, should I put up a plastic (6 mil) vapor barrier before installing the inside wood paneling?

I am in SC, and will be cooling and heating my barn shop building.

Thanks for help in advance.

 

[bookman51]

I talked with the Wicks representative from company headquarters (it is a Wicks building). He was good enough to call back. He recommended sliting the existing insultation vapor barrier (painful is it will be for more) then installing insulation over it if I want more before installing drywall and peg board.... and then putting heavy plastic on the inside as a vapor barrier. He said guys change their minds all the time as they go to finish up the building and this is what Wicks recommends.

I also have gaps at the base in the uninsulated part, and I asked about that, and he said it is okay (in fact a good idea) to put something in them. I probably will start out with foam of some sort--to cut down the air flow from the outside.

I do not plan on heating it to 70 degrees or work in it all day, but I do want something that keeps the wind out and I can warm up to a decent temperature, even if it means working in a coat.

Thanks for advice.

Bookman

 

[anojones]

Cutting the old vapor barrier makes sense, allows the moisture to move back and forth. In terms of adding plastic over paper backed fiberglass in a wood structure, I probably wouldn't bother if I could face staple the insulation and have a pretty complete barrier. Some folks would rather have a better vapor barrier than the kraft paper and would add plastic ( I did, but my siding is metal). It would be cheaper and make more sense to put up unfaced batts and then use a plastic vapor barrier, that way you only have one and moisture won't get trapped between the kraft paper and plastic. I only used kraft faced because it was all I had easy access to.