# Vapor Barrier for Shed Office



## shaneb (Jan 2, 2013)

Hey folks, I am building a shed office in the backyard. It's being delivered and built on site, but a vapor barrier is not included. Since I intend to cool/heat/insulate the shed, I think I need one. 

I have the 6mil plastic, the site is cleared. The question is am I better off to put the plastic on the ground before the frame goes down (2x6 zinc coated steel) or am I better off to stretch the plastic between the OSB SmartFloor and the frame once the frame is down. 

If I put it on the ground, what should I do with the edges? I had heard I should attach them to the inside edge of the 2x6 rim joists, but that seems it would create an unvented space and hold any moisture that happens to form there. 

Thanks in advance, 
Shane


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## Windows on Wash (Aug 30, 2011)

Where is the home/shed going to be located?

What do the shed instruction say? A vapor barrier across the floor would be a good thing to keep any moisture down and under the plastic but a vented space (much like a crawlspace) would be preferred.

What is your insulation schedule for the floor?

Rigid foam across the bottom of the framing would be a good thing if you are going to heat and use this thing.


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## shaneb (Jan 2, 2013)

Located in Tulsa Oklahoma. 

No instructions with the shed. It's a Tuff-Shed, so they build it. They will build the frame on grade with steel 2x6. So there is need to keep moisture off the joists really. They will allow me to install a vapor barrier if I want, but they don't seem to be worried about it or offer it as an option. They do offer Tyvek on the walls instead of radiant barrier. I am taking that option. 

But I would like to keep it off the floor. So that's why I thought about putting it on the joists before the floor goes down. Especially because the floor will only be 6-8 inches off the ground. 

The amount of insulation I could put under there with foam board really wouldn't pay dividends I don't think and could cause problems with drainage etc. Thin foam board is all of what? R-3.5 or something?


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