vapor barrier question

[rieferman]

I'm in PA, cold winters / hot summers. The barn breathes exceedingly well overall.

The workshop space is heated "as needed" on average about 2 hours per day, and longer on weekends. When I'm not in there, the space is not heated. I do not have a vapor barrier in this area. Walls are OSB.

Cost issues prevented me from using vapor barrier, and my feeling was that given the limited amount of time that the space is heated (i.e. the limited amount of time that condensation could occur) and the amount of air movement through the building (i.e. it could easily dry out if condensation did occur) that in reality it will be fine.

But it's eating at me. I know "the right way" would have been to wait another year, save for the right materials... but in actual real world (not holmes on holmes world) what do you think?

 

[bgarrett]

vapor barrier is CHEAP

and essential

use it even if you dont add insulation

 

[rieferman]

I understand, in this case, there was $0 to allocate, and I had free insulation. OSB is already up.

So... again... the question isn't "what is the correct process" as I know the answer is "use a vapor barrier".

My question is: "given the situation, usage, breathability of the building, materials... is it really a stop-the-presses-take-it-apart-and-do-it-over issue, or is it going to be just fine"

 

[e-tek]

C'mon reifer....a roll of 6mil poly is about $85 around here and covers 2000sq ft......but hey, we make decisions based on the info we have at the time - right??

But you say you already sheeted it with OSB? Tough to get that down to install poly now! If you where going to sheet over with drywall or metal, then I'd add the poly then.

By the way you describe your place, I think you're right in that you're gonna be OK with what you have. If it's "breathing" (leaking) as much as you say, it shouldn't condensate much....

 

[rieferman]

a roll of 6mil poly is about $85 around here and covers 2000sq ft

heh heh heh... I know.. $85 seems like nothing, but all the "small expenses" seem like nothing by themselves, so sometimes there's a line in the sand.

In the tighter areas of the building (like the office) that are kept at constant temp, I have the vapor barrier. But, it is what it is.

By the way you describe your place, I think you're right in that you're gonna be OK with what you have. If it's "breathing" (leaking) as much as you say, it shouldn't condensate much.

Oh, it's leaking, that's for sure. With all the dust I have swirling around, the dust collection system emptying my heat to the outside vent, an overhead garage door, gaps in the exterior barn board, and spaces between OSB and posts/beams... "tight building" wasn't even on my radar in this space.

Ok, I think I'm good. Just wanted to gut check. When I finish the 2nd story into a rec room, I will use a vapor barrier since it will be much tighter space and heated full time (like the office).

 

[kb2tha]

It might help some to paint the wall surfaces with a heavy coat of oil based paint. This would help in keeping some of the moisture from escaping through and into the walls. Moisture would still escape around any outlet openings in the exterior walls. Hope this helps. The paint would be like what my wife says about me. "Better than nothing". Ken

 

[scuba0459]

I think that the real value in using poly over the insulation is that it becomes a great air barrier. drywall or any tight wall covering is also a great air barrier. The amount of moisture you are putting into your shop is minimal compared to a house so the likelihood of getting moisture damage or mould is less. You can buy vapor barrier paints that will help seal up the building.


That my .02 worth

Albert

 

[jklingel]

... as I know the answer is "use a vapor barrier".

Unfortunately, it is NOT the answer, necessarily. You MAY be better off w/ one, but in PA I doubt it. AIR sealing is what is important. Poly vapor barriers can be problematic and are being discouraged in all but the coldest places. In your situation, it sounds like it is an either way deal; limited use, probably low interior moisture. However, if you build a house, you may want to check out articles here. http://www.buildingscience.com/resources/more-topics/vapor_barrier_code_changes