I have a 24x30 workshop with an upstairs. The upstairs is floored and has knee walls, thats it for now. One day it will be a gameroom or something and possibly heated/cooled, but who knows IF or when. I dont want to try and heat or cool it all together (up and down) so I decided its time to insulate the downstairs where I work on my car. there currently is NO insulation anywhere, and the walls and ceiling are unfinished/open. I started insulating the ceiling with unfaced R30 this weekend. Unfaced because it was on clearance. My ceiling/floor is 2x12's. He said I should add a layer of 4-6 mil plastic across the whole ceiling, then drywall or plywood to follow. I understand a little about the vapor barrier, but is this plastic still ok to do with the upstairs being a room that may be heated/cooled in the future as a game room? If I read correctly this would be OK if it was "attic" upstairs, but my upstairs may be finished out and climate controlled. Same question on the walls. I have R13 faced for the walls, plastic or no plastic? This is in west TN climate. Heat will be electric 220v more than likely and will only be used as needed to create a cozy work environment when its below 40 outside.
You don't want two vapor barriers so only the paper on the r13 is right. Between floors should be unfaced but I bet you'll get different opinions on it. In a two story it's more of a sound barrier than anything else. IMHO.
Yeah I have heard that about in a house you would use unfaced for sound, which I actually did in my house. The main reason he mentioned using the plastic on the ceiling was for trapping more rising heat downstairs. I guess it would also be a barrier because for now, the down stairs would get heat and the upstairs would not. My upstairs has a permanent stairway with a door, and I am treating the up as an "attic" for now, completely insulating the downstairs, none upstairs for now. I am striving to keep as much heat as possible from going upstairs
The vapor barrier should only be on the roof, if you make one between the floors you'll have issues later on when you insulate the roof. I would think that the insulation would provide enough of a thermal barrier, which sounds like what you are looking to do.
I guess your not in Minnesota- here its 40 below to work in the shop, not below 40! Be sure to leave an air space , or chutes between your roof and insulation, it sure makes a difference - Good Luck , Bill
Put the plastic down now. Like you say you may never get around to doing the up stairs. Wet insulation is no good.
Just figure out you only need a vapour barrier between a hot and cold wall--anywhere else is a mould problem
Ok, so to me it sounds like the best thing would be to not vapor barrier the ceiling between floors. What if I did put plastic down now between the 2 floors, then decided to heat both up and down in the future? I guess my thoughts are I want to do whats best, not whats cheaper or less work.
Insulation in your home won't have a vapor barrier, think blown insulation. If you decide to heat the upstairs then you'll need to put in another ceiling and insulate above it or insulate the rafters.
Ok, sounds good. So what are you thoughts on if I have no barrier between the floors, heat the downstairs with electric heater (only when working), and the upstairs is cold. Would it sweat between the floors at that point?
since your roof is not insulated you still have a cold zone, so insulating the game room floor you will still have a moisture buildup, you will still need a vapour barrier, now if your roof was all insulated and vapour barriered then you would not need to vapour barrier the floor.
thats what I was afraid of. So looking at it that way, the only right way to do this would be to either barrier between floors, or go ahead and insulate and barrier the upstairs roof with no barrier between floors. Right? I just didnt want to insulate upstairs yet, mainly due to costs.
i have had my garage since 82.it is 24x36.i put vapor barrier on the floor before the cement was poured,insulated the walls,put vapor barrier over the insulation before the drywall,insulated the ceiling,put plastic on that also between the drywall and insulation,floored the attic. i can put a piece of bare steel in that garage for years,and it won't even think about surface rusting...unbelievably dry.the difference in the attic space is huge,as far as temp.very cold in winter,very hot in summer.i do have an attic fan and two vents for summer though. i run heat and air in the garage to work in.i leave the thermostat at 45 in winter,unless i'm down there.i have had no problems with this setup
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