Replies

1. 
   IMERC | Aug 20, 2006 08:36am | #1

   cold..

   googled and it seems this opinion is unanimous...

    

    

   Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming

   WOW!!! What a Ride!

   Forget the primal scream, just ROAR!!!

2. 
   IronHelix | Aug 20, 2006 03:03pm | #2

   In addition, make sure the warm side wall and penetrations are caulked to prevent air infiltration which would carry humidity to the cold wall.

   ................Iron Helix

1. 
   BillHartmann | Aug 20, 2006 04:05pm | #4

   "In addition, make sure the warm side wall and penetrations are caulked to prevent air infiltration which would carry humidity to the cold wall."I am not sure, but I suspect that the humidity drive is from the cool side to theh warm.

1. 
   IronHelix | Aug 20, 2006 11:17pm | #9

   Energy movements were according to a law of thermodynamics, entropy....from higher energy to lower. So the energy level of warm air(higher energy) with higher humidity would cause it to move to the cooler side, lower energy. If the cooler surface(wine cellar wall) was at the condensation/dewpoint, then the water would accumulate at the cellar wall if it were not permeable at a rate high enough to transport the water to the inside of the cellar.  Air barriers prevent flowing of higher heat & humidity energy levels to cooler surfaces.  Moisture barriers impeade the movement of water & humidity as per their specific ratings.

   Wine cellars for bottled wine should be cool and slightly humid, as not to dessicate the corks, but not high enough to cause mold/mildew.  Walk a taughtline!

   This is surely a balancing act, and all the facts are not present...we we are speculating/theorizing.

   .............Iron Helix

    

1. 
   DanH | Aug 20, 2006 11:23pm | #10

   The heat energy will move from warmer to cooler, but air doesn't necessarily move that way, nor does the moisture. Moisture will tend to move from higher humidity to lower, though I don't recall enough of college thermodynamics to say whether that would be relative humidity or absolute humidity.

   If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

2. 
   BillHartmann | Aug 20, 2006 11:29pm | #11

   "So the energy level of warm air(higher energy) with higher humidity would cause it to move to the cooler side, lower energy."See that is where you are making assumptions about the humidity levels.We don't have any idea of the location, but in many parts of the country you might have 70*/20% RH in the winter.And what is the RH in a wine cellar?

1. 
   steve151 | Aug 21, 2006 03:13am | #12

   I don't know exactly what the humidity in the wine room is going to be but in Wyoming the humidity is fairly low mmm.... maybe 10-15% .

2. 
   RayMoore2G | Aug 21, 2006 04:27pm | #13

   This is a long post but there is a great story at the end about the space shuttle as a reward for your patience.

   The easy way to calculate this is to go to a website with a dewpoint calculator. Calculate the dewpoint of the interior conditions and the exterior conditions of the wine room. This may change of course as the seasons change. Just input the temperature and relative humidity to find the dewpoint. Use averages, as spikes can be ignored. In almost all parts of the country, moisture movement will be towards the interior of a wine room. Moisture will move from a high dewpoint area to a low dewpoint area. The vapor barrier should be on the high dewpoint side of the wall.

   I'll do an example:

   If the temperature is 55 F and the relative humidity is 50% then the dewpoint of that air is 36.73 degrees. If the air in the house is 70 F and 30% RH then the dewpoint of that air is 37.18. In this example there would be a slight tendency for water vapor to move towards the interior of the wine room. You might expect these conditions in the winter months.

   If we look at summer conditions, we might find house conditions of 75 F and 50% RH. This air would have a dewpoint of 55.12 degrees and would exhibit a stronger tendency for vapor to flow into the wine room.

   If the wineroom is on an exterior wall or a garage wall, then the conditions would be much different. Of course, climate will radically change the calculation. If you look at exteror conditions of Houston, TX in summer you might find an average dewpoint of 73 degrees which would create a strong inward vapor drive towards the 36.73 degree wine room conditions.

   There are parts of the country where the drives would be outward, at least for part of the year. The safest method for constructing a wine room is to use continuous rigid foam insulation either inside or outside the framed walls. I have seen studs act as a slow but insidious transport mechanism for moisture, in wine rooms with strong vapor pressures, when foam insulation was cut to fit in the stud bays.

   The strongest transport mechanism for water vapor is air. You must air seal the wine room perfectly in order to prevent airborne moisture from condensing on the cold interior surfaces when exterior dewpoint temperatures are above 55 degrees F.

   If you think wine rooms are complicated to calculate, try a walk in freezer some time.

   To really blow your mind, calculate the vapor pressure difference on the fuel tank of the space shuttle. The liquid hydrogen is stored at -423 F. The dewpoint in Fl. in summer averages 75 degrees. That is a temperature difference of 500 degrees F. Add to that the afternoon rains and solar heating on the west side of the shuttle each afternoon and you see the difficulty that NASA has in trying to keep ice from forming on the aluminum can they use for a fuel tank. Their solution is to use one inch of closed cell spray foam insulation. Does anyone else think this would actually work. Imagine it's a really really really cold beer can in a coozy.

   This is a picture of the first space shuttle. http://apod.nasa.gov/apod/ap010412.html

   Take note of the fuel tank. The reason it is not the orange color that we have grown used to is because it was covered with a vapor varrier. The first three shuttles had a vapor barrier on the warm side of the fuel tank. It is my understanding that this was scrapped to save weight. Without the vapor barrier, ice forms on the aluminum skin. I wonder what the ice weighs. Anyone wonder why this is never part of the news stories we hear about the shuttle? The problems they're having with the shuttle are the same ones we face in a wine room but on a massive scale.

   Here is a link for a simple dewpoint calculator. http://www.decatur.de/javascript/dew/index.html

3. 
   IronHelix | Aug 22, 2006 02:16pm | #17

   Yes, we are speculating about the humidity at the different locations and conditions.

   One would expect that an inhabited room at 70+ degrees would have a higher humidity level than another room at 55.  What is not known is exactly how much difference and if seasonal differences/driving forces exist that may make the potential problems bimodal.

   I still feel that sealing the drywall at the house side would reduce air and moisture migration to the cooler side at the wine cellar.  If condensation is finally considered to be a major concern then include a safe exit for what might collect on the backside of the vapor barrier at the cold wall.

   And after reading these convoluted posts, I can see why one poster decided not to build one for a potential customer.  The liability for loss of quality and elite wines would be risky, not to mention generation of a moisture problem that might damage a structure.

   Time to hire a specialist in wine cellar design and construction, then his O&E can cover the builder's butt.

   ............Iron Helix

    

4. 
   DanH | Aug 22, 2006 04:39pm | #18

   > One would expect that an inhabited room at 70+ degrees would have a higher humidity level than another room at 55.Actually, I'd expect the opposite, if you're talking relative humidity.
   If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

3. 
   BillHartmann | Aug 20, 2006 04:03pm | #3

   You left out one big detail.

   The HUMDITY LEVEL.

4. 
   Dave45 | Aug 20, 2006 04:51pm | #5

   I was asked to bid on a wine room a couple of years ago and backed off after I did some research.  It would have been a fascinating job, but it was way more involved than I felt comfortable taking on.

   I believe that your customer is right on this one - if the humidity in the wine room is lower than the other rooms.

   Condensation occurs when the air temperature drops to its dew point, and will collect on the side of vapor barrier facing the highest humidity.  (Think of cold water pipes in a humid basement.)  Since you don't want the condensation in the insulating material, the vapor barrier needs to face the side with the highest humidity.  You'll also want to minimize the number of penetrations and seal up those you can't avoid.

    

1. 
   steve151 | Aug 20, 2006 05:19pm | #6

   I forgot to mention that there is also going to be a humidifier for the wine room. Do you think that I should still put the vapor barrier on the warm side?

1. 
   Dave45 | Aug 20, 2006 05:56pm | #8

   Ah, yes - now I remember more of why I decided to pass on that wine room job - lol.

   I don't remember any specific websites, but there are several that have loads of info on designing wine rooms.  You might want to do some searches on "Wine Rooms" and see what pops up.

   As I recall, the whole temperature/humidity issue was pretty involved and the equipment was very expensive.

   Hammer1 suggests using unfaced insulation which may work - if the humidity levels on each side aren't too different.

1. 
   CapnMac | Aug 21, 2006 07:48pm | #14

   if the humidity levels on each side aren't too different

   Which is a requirement, from my research on wine storage--has to be right up there, RH of 15-18% to keep the corks from drying out, is what is alleged.

   Of course, for a reason to pass on a wine storage room, here's my fave:  The client is typically buying by the case, and likely already has 175-500 bottles to store.  Means any uh-ohs with temperature, humidity, racks, etc., that damage claim is right stiff (100 $20 bottles being $2000, and these are almost never $20 bottles <sigh>).

   I'm waiting to see if I get used as an expert witness in a mold case, said case not looking good for the builder, not with exotic mold on the corks & labels on just shy of 3000 bottles . . . Occupational hazard of my occupation not being around (sorry Bubba)

1. 
   Dave45 | Aug 22, 2006 02:47am | #15

   Keeping the corks moist isn't a problem if the bottles are racked.

   Another problem with home wine rooms is floor loading.  The job I passed on was going to have 5000 bottles.  I wasn't looking forward to trying to beef up the floor in a 16" crawl space - lol

2. 
   CapnMac | Aug 22, 2006 07:15am | #16

   Keeping the corks moist isn't a problem if the bottles are racked

   That's what I was taught, too--but, I'm not a snooty wine collector, either <g>

   The vintners all have weird temperature and humidity requirements, though, when asked.  Almost as picky as for cigar humidors.  Harder than spit to achieve, too, if the discovery info so far is any guide.

   (I suspect some of the collectors are more worried about the case stock that stands up, as they never have enough racks--but that's just a guess.)Occupational hazard of my occupation not being around (sorry Bubba)

5. 
   BillHartmann | Aug 20, 2006 05:22pm | #7

   The best solution is not to have a vapor barrier at all.

   Use a vapor retarder with continouse insulation.

   IE, sprayed foam or sheet foam insulation.

   As another post said really what you need moisture away from surfaces below the dewpoint.

6. 
   Tim | Aug 22, 2006 09:11pm | #19

   I think it matters very little, actually. The conditions inside (of the wine cellar) are going to be mostly constant. The outside conditions are going to change, but not much in relation to the inside. I believe that the vapor barrier should go on the outside.

   I would let the Golden Rule decide this one for you, i.e. the one with the gold makes the rules. They're paying the bills and it doesn't matter, so let them decide.

1. 
   steve151 | Aug 23, 2006 04:15am | #20

   Thank you . I think that is very good advise!

    

   steve151