Replies

1. 
   John_Kunigonis | Feb 03, 1999 06:28pm | #1

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   I live in San Diego about 20 miles in-land from the cost. It gets hot (100 degrees F as the high) in the summer and cool (30 degrees F as the low) in the winter. I am building a wine cellar with a cooing unit in my house. Should I use a vapor barrier in the wall? Should the barrier be on the outside or inside of the wall cavity? What will happen with no vapor barrier in the wall?

2. 
   John_Kunigonis | Feb 03, 1999 07:24pm | #2

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   I live in San Diego about 20 miles in-land from the cost. It gets hot (100 degrees F as the high) in the summer and cool (30 degrees F as the low) in the winter. I am building a wine cellar with a cooing unit in my house. Should I use a vapor barrier in the wall? Should the barrier be on the outside or inside of the wall cavity? What will happen with no vapor barrier in the wall?

3. 
   Guest_ | Feb 03, 1999 10:16pm | #3

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   John,

   I saw a design that had a 6-8 mil poly vapor barrier on the exterior (warm side) of the stud bays and ceiling joists of the wine cellar. The barrier was put up first with the seams taped, then 3-5 in of rigid foam, followed by plywood, followed by racks screwed to the plywood. The cooling unit was vented to conditioned space adjacent to the cellar, mounted high on the wall.

   Larry

4. 
   gary_ | Feb 04, 1999 01:59am | #4

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   That's easy. Moisture, at times I imagine, exists in your region of the country. Moist air will condense moisture out of it as it cools. If you take an example that I can only guess at is that your house, wine cellar or not, will often be cooler than outside. This means that most of the year you want to keep moist exterior air away from your wall framing (studs), so put a vapor barrier on the exterior of your studs, then sheathing & siding. If you don't, as the air cools (within the insulation located, I guess, within your studs) it will condense moisture out of it in the stud cavity. This will drip and warp and eventually rot out your studs. Obviously, you don't have as extreme a situation as many other areas do. The worst situations would be the southeast where the exterior is often very moist air or in the north where you have interior air to worry about. Interior air is very often moist due to all the point sources of moisture production within a home. There is a way of figuring out where the moisture will condense if you want to know, but suffice it to say that your worst case scenario would be that the air condenses on the exterior face of your sheetrock and you get really quick rotted walls. The repair would be painful for sure.

5. 
   Guest_ | Feb 04, 1999 01:59am | #5

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   What is your opinion on the use of vapor barriers in new construction and remodeling?