Vapor Barrier ?

[Mmfh]

Alright, when is it and when is it not necessary to run a plastic barrier when finishing a attached garage for working purposes?

I want to make it warm and still working on what type of heat source but I keep reading about guys using a plastic poly sheeting prior to whatever they are finishing with.

Why is that, and is it always necessary in a garage?

Also wondering about the garage attic area, dumb roofer put a vent in the garage area and now unless I finish the ceiling I'm going to lose my heat right out that vent. I'm thinking about covering that vent with something on the inside.

What about insulating the actual roof of the garage? I've never seen it done where the roof is insulated and finished instead of the ceiling. Does there need to be air movement under the roof sheeting?

Trying to get my head wrapped around sealing up this garage.

Thanks you!

Mm

 

[kbs2244]

http://www.naturalhandyman.com/iip/infxtra/infinsul2.html

You put on the warm side of the insulation to kee water vapor from getting into the wall and then condensing.

You can insulate the underside of your roof jusy like a wall.

Make some kind of adjustable shup off for your vent.
You will want it in the summer to vent heat and may even need it in the winter if you do anything that puts a lot of humidity into the garage.

 

[NUTTSGT]

I'd prefer to insulate the bottom of the trusses and put up a ceiling rather than insulating the roof. I think it looks cleaner. If you need access above the rafters for storage, make a simple access panel.

 

[WVBrady]

...You can insulate the underside of your roof jusy like a wall...

I have heard of people having trouble with condensation if they don't leave room for air to circulate between the insulation and the roof and don't have a path for ventilation. The difference between that situation and the walls is that you have a second vapor barrier formed by the roofing material, whereas in the walls you should not have a vapor barrier on the outside (except, perhaps in a cooling only environment).

 

[kbs2244]

You can insulate the bottom of a roof like a wall.
It is done all the time with homes that have “vaulted” ceilings.
The vapor barrier will keep the moisture away from the roof.

If you have an attic space above a flat ceiling, then you need to get into ventilation for summer heat and winter moisture removal.

http://www.finehomebuilding.com/how-to/articles/a-crash-course-in-roof-venting.aspx

http://www.finehomebuilding.com/how...-works/vapor-drive-reducing-condensation.aspx

The roofing material is a moisture barrier, not a vapor barrier.
It will stop liquid water but water vapor will pass through.

The "house wrap" used on a wall does the same thing.
It keeps liquid water from the outside frome getting into the wall, but lets any water vapor that did get into the wall out.

 

[Mmfh]

You guys have given me some good info about this. Thank you!

I do have some more reading to do before I've got it completely figured out. I want to store things above the ceiling in the garage without any damage to things I'm storing. I now have a vent in the roof sheeting thanks to the roofer.

Working in the garage I could very well generate condensation and smoke at times, who knows what could happen in a working garage.

Just not completely sure what to do yet.

Thanks

Mm