Vapor barrier on ceiling needed?

[scoob8000]

Just finished my pole barn style garage. I really can't afford to insulate it, but I'd really like to get some wood up on the ceiling before I start trying to mount lights.

I'm in the north east in western PA. Garage is 7/16 OSB wrapped in tyvek then vinyl siding. The roof is also OSB covered with felt then asphalt shingles. I have good soffit vents, and a ridge vent installed.

Can I just put my OSB ceiling up and run my wires then come back an insulate up there down the road? Or should I put up a vapor barrier before the wood?

 

[MScott]

Definitely put up the vapour barrier. It would be almost impossible to do it later and it is needed. It is also very simple at this time.
Put your location in your profile so people don't have to look it up in your post. Your location is very relevant for this question.

 

[bullnerd]

Check out my build thread in my sig, just installed a vapor barrier.

 

[G McKay]

I would definitely go with the vapor barrier. It will pay off in the long run.

 

[scoob8000]

Definitely put up the vapour barrier. It would be almost impossible to do it later and it is needed. It is also very simple at this time.
Put your location in your profile so people don't have to look it up in your post. Your location is very relevant for this question.

Could I just staple it up to the bottom of the trusses before putting up my OSB?

And is there a specific product for this, or just use house wrap?

I'm eventually going to insulate up there, but I can always cut a access panel or two in later.

Check out my build thread in my sig, just installed a vapor barrier.

Looks nice! I really want to fully insulate mine now, but after the cost of building it and re-doing my house roof it's just gonna have to wait.

 

[wildstyle]

Yes it gets stapled to the bottom of the trusses. You want a 6 mil plastic vapor barrier. Tape you seams with tuck tape and seal your edges with acoustical sealant.

 

[kbs2244]

I disagree completely.
With a well vented attic space you do not want a vapor barrier in the ceiling.
Do some research on insulation installation in northern areas.
The heated area need to “breathe.”

 

[TOOL FANATIK]

it should get vapor barrier. no houses these days breathe anymore in light of efficiency and energy savings, green homebuilding. HVAC systems suffer from working so hard to pull air, these new homes are so tight. it really depends on the theory you chose to believe in the most. for every advantage there seems to be a disadvantage and the pros seem to always disagree on topics such as this one... but whatever you do, do not use acoustical sealant anywhere around an exterior wall, condensate will form on the surface along the entire bead subject to the exterior side. i use spray foam in a can, it insulates as well as seals. it's "great stuff!!"

 

[scoob8000]

I disagree completely.
With a well vented attic space you do not want a vapor barrier in the ceiling.
Do some research on insulation installation in northern areas.
The heated area need to “breathe.”

This is exactaly what I was wondering. More so because of it being a garage. Do we want it to breath some or not.

But what I'm thinking is if I'm running heat in the winter, without a barrier won't condensation form on the roof decking?

i use spray foam in a can, it insulates as well as seals. it's "great stuff!!"

Sounds like pretty great stuff. Whats this stuff called?

 

[dirttracker18]

I disagree completely.
With a well vented attic space you do not want a vapor barrier in the ceiling.
Do some research on insulation installation in northern areas.
The heated area need to “breathe.”

And you would be incorrect.

If the OP has the intention of insulating the space then the vb is necessary.

You do not have to worry about the space breathing as you will never get the service door to deal well enough for that to be any kind of concern.

Do some research, as you noted, and you will find is is not only recommended in northern areas but code as well if a dwelling. Seal up as well as you can on walls and ceiling. If you use some free heat loss calculators you will find that the vb is actually more effective then the insulation.

 

[ShadowRuleZ]

I've been researching blowing in cellulose and some of the manufacturers don't recommend a VB.

 

[bullnerd]

I pretty much copied what Morton buildings does. They've built a few buildings and if it was a problem ,I'm sure they would have figured it out by now. Also, my neighbor has had a Morton with VP for more than 20yrs, I've been in the attic, no signs of moisture, mold, or little green men.

 

[TOOL FANATIK]

Scoob800 the spray foam is actually called great stuff lol

 

[kbs2244]

As I stated “a well vented attic” will not need a vapor barrier.

And a very important thing to take into consideration is “dwelling space” vs. “auxiliary space.”
We are not talking about a space where are in our underwear and cracking a brew to watch our favorite team. We are talking when we are dressed, maybe overdressed, for work.
As one of the sites noted, garages are “leaky.”
And water vapor follows heat on its way to cold.

So do not confuse home with shop needs.
We open 10 to 16 by 7 foot openings in our “garages” or “shops” all the time.
A lot of water vapor goes out every time.
And we put up with leaks at the corners of the overhead doors that we would never put up with in our living rooms.

http://www.jlconline.com/insulation/q-a--ceiling-vapor-barrier---yes-or-no-.aspx

http://www.ankn.uaf.edu/publications/VS/insulation.html

http://en.wikipedia.org/wiki/Vapor_barrier

http://energy.gov/energysaver/articles/vapor-barriers-or-vapor-diffusion-retarders

 

[jayoldschool]

Hi Scoob!

Show us some pics, and tell us more about the building...

 

[Highbeam]

Oh yes, VB on the ceiling under the wood. An air barrier as much/more than a VB.

 

[scoob8000]

So vapor barrier it is!

Build log and gallery is in my sig now.