Vapor Barrier HELP

[Alaska4Ever]

I live in interior Alaska so needless to say the temperatures here are extreme in the cold category.

My shop is 45 wide by 50 long and 14 foot ceilings with an 8 on 12 pitch. Metal siding with truss construction. Old pole barn that has been converted.

I am finishing out the inside so i can insulate and getting ready to put up the interior ceiling. I have basically two options... Sheetrock the ceiling or put up metal interior panels (basically metal roofing without the UV protective paint)

My questions are:

1. IF i put up the metal and seal all the lap joints is a plastic vapor barrier really necessary?

2. If i put up the sheetrock i do not intend on taking the time to tape and float the joints.. not my DIY expertise obviously i would put the plastic up but just wondering if not taping the joints would cause issue as some point.

Thanks for the help and any advice... just trying to cut cost as much as possible as the overall cost of insulating the ceiling and walls and then electrical and final finish work gets EXPENSIVE.

 

[ckyle29]

Yes, put up the vapor barrier whichever route you choose to go. A little money spent now could save you a bundle later.

Will it ever positively be air-tight? Probably not and without the barrier, assuming you will be heating the garage, all that warm moist air will eventually make its way through into the insulation where it will create mold. Then you will have the hassle and expense of removing/replacing all the ceiling insulation, which will cost much more than the plastic would.

 

[Jess]

You will want the vapour barrier, regardless of the interior finish. The object is to eliminate air infiltration of the insulation and prevent moisture buildup inside the wall. If you choose drywall, its not all that difficult to finish but will not make any difference except for any permit requirements. Board it now and you could finish it sometime in the future but do the vapour barrier and make sure its taped and sealed properly.