Brewpastor's Coldroom Build

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Going back to page one and the insulation facing. In home building the term used to decide which way the vapor barrier faces is conditioned space so the barrier would face insde. If you use a vapor barrier on the unconditioned side it will trap moisture and cause mold. That is why the new external house wraps (tyvek) are "one way" barriers and allow moisture to escape. I am not a fan of plastic as as I have seen alot of moisture buildup and run to the bottom of the wall. Most builders I have worked for opt for the kraft (paper) backing.
 
bigdug said:
Going back to page one and the insulation facing. In home building the term used to decide which way the vapor barrier faces is conditioned space so the barrier would face insde. If you use a vapor barrier on the unconditioned side it will trap moisture and cause mold. That is why the new external house wraps (tyvek) are "one way" barriers and allow moisture to escape. I am not a fan of plastic as as I have seen alot of moisture buildup and run to the bottom of the wall. Most builders I have worked for opt for the kraft (paper) backing.
Click to expand...

So in other words, forget the plastic, and install from the inside. I am glad to know I did it right! Thanks. :mug:
 
bigdug said:
Going back to page one and the insulation facing. In home building the term used to decide which way the vapor barrier faces is conditioned space so the barrier would face insde. If you use a vapor barrier on the unconditioned side it will trap moisture and cause mold. That is why the new external house wraps (tyvek) are "one way" barriers and allow moisture to escape. I am not a fan of plastic as as I have seen alot of moisture buildup and run to the bottom of the wall. Most builders I have worked for opt for the kraft (paper) backing.
Click to expand...

But in building the conditioned side is the side that is heated. Heated air holds more moister than cold air. There will be an imbalance in moisture as the A/C is going to dry the air inside the coldroom. The warm moist air will go towards the cold in the insulation and as it hits the colder vapor barrier on the inside wall it will condense. Its not like a/c in the house during the summer you aren't getting the home down to 35-40°. The cold inside wall is going to act like a cold bottle of beer on warm summer day.

tyvek is great but you still need a some type of barrier to stop the moisture from migrating on the warm side. So the rules need to be reversed here.
 
That's pretty much what I said twice but my additional 2 cents is that the guys saying "on the conditioned side" are probably from the Northern climates where the heating season is equal to or longer than the cooling season. Think of the temperatures involved up North. During the summer you have a typical 80-90F at 60% humidity. If that air hits the inside cold side of the wall, that wall will be about 75F and you'll maybe get a touch of condensation. Reverse that to the winter when it's 20F outside and 68F inside at about 30-40% humidity. Here's where you really want to keep the warm air away from the cold side. Look at the temp delta there.

In Southern humid states it's exactly the opposite. The warm moist air is always outside ambient. The cold side is always inside the house. Vapor barrier on the outside.

Western dry states? Who knows. If I guess, Brewpastor's garage is most humid during a brew session. If it stays that way long enough, it could get into the cold room wall and condense against the cold side. Problem, likely not.
 
but even in the deep south the gradient isn't to the extreme of our winter nobody cools their home to 30°. So I would think its the same as our conditions in Summer. This is why tyvek is required on new construction. it allows the moist air that does get threw the wall to escape and doesn't let the outside moisture in. I don't know the humidity levels in NM but I assume they do get rain and some moist days . I would say if the vapor barrier is on the inside wall of the coldroom I would put some tyvek on the outside just to keep any moisture from getting to the cold.


And the A/C will make the inside dry as a bone.
 
New Mexico is dry, except for today when it is really wet. But the rain will stop and it will be really dry again. It is so dry here we complain when the humidity is over 30%! Not like SW Missouri where I grew up.
 
Ya we get some real soupy conditions here. My central A/C sometimes the pump is going all day to drain the drip pan and my fridge will sweat .
 
BP, check your A/C sensor. If it is one of the plug-in types you can just replace it with a switch and be done with it. If it is soldered in and not replaceable either a resistor or nichrome wire (my preference can accomplish what you need. But figuring out resistor values and heat generation based on wall warts you have lying around doesn't really make much sense if you have a removable sensor.
 
I live in central nc where, 90 plus dgrees and 90% humidity is the norm all summer, and the vapor barrier ( plastic or kraft backed paper) is required on the conditioned side of the wall. My understanding is that is why you need a vapor barrier with a lower perm rating on the exterior (housewrap,tyvek, asphalt impregnated sheathing) on the outside to allow moisture to escape back out and not be trapped inside the wall. In New mexico with the constant low humidity it may be a moot point.
 
Looks like you're off to a great start BP! I can't wait to see how this one progresses!

-Tripod
 
OK, two more images. The wiring is 99% done, and the insulation is in - vapor barrier towards the inside!

P1010681.jpg
[/IMG]

P1010682.jpg
 
P-Lay said:
Do you plan on insulating the door?
Click to expand...

+1 to insulating the door. Just a fair warning, if its a hollow door, DO NOT use the spray in expanding foam. I did this on a door to make it more sound proof in our old house, and that foam will expand and split the door within a day. If there is anyway to take the face off the door, I would and install some insulation that way, glue and clamp back together.
 
Brewpastor said:
Thus far I have spent:

wood for framing - free
2 sheets of plywood for floor - $19 each
insulation - $90
solid core door - $10 (Habitat Restore)
door hardware - free
8000 BTU AC unit - $199
wiring, switches, outlets and boxes - $32.
Click to expand...


He's using a solid core door.

Project's coming along nicely!!!
 
OK, more advice desired.

I plan on using sheet rock on the exterior, and am thinking of just doing the same inside. Thoughts?

plywood, foam board, composite...
 
You could probably get away with taped up plastic contractor's sheet, hehe. I think those fiberglass pebble sheets mentioned are about ~$30 per 4x8 sheet. It would at least look pro without the cost of SS :)

Congrats on the coolbot! Although you did end all of our geek dreams lol.
 
You could go with 1/4" HDF for strength, then use contact cement for 1/16" white melamine. Anything you can wipe down with an oxyclean slurry sounds good.

Trust me, I was tempted to suggest 1/8" stainless diamond plate.
 
If those plastic sheets that I walk by at Depot are ~ $30 a pop, I'd just go that route and not worry about it. You're not going to need THAT many sheets, it's a pretty small space, might as well do it right and not have to think twice about condensation.
 
For the vapor barrier... I used 6MM plastic sheets and wrapped it on the outside of my studs (so outside of the insulation) but then inside the outside plywood... so... it goes plywood, vapor barrier, studs, extruded foam insulation (4 inch thick sheets) and then the inside of the cooler... and I've never had a problem with mold EXCEPT for a 2 foot by three foot section that I never bothered to insulate when I first built it. Because it wasn't insulated,t eh cold sucked the moisture right outta the room through the wood and the outside of my walk-in got a little mold on it. Once I finally tossed the insulation up, I haven't had a problem since. Nor have I had any problems anywhere else on the cooler.

I'm sure NM is really dry... but it won't take much. You would be surprised.
 
... oh... and yeah, I would def avoid sheet rock.

and what was all the talk about a heater??? I got lazy and stopped reading... are you nervous about your coils freezing up?? It sounds like the coolbot will prevent that anyway but I've only had a few instances of my coils freezing (about three) over the two years or so my walk-in has been up and running and it was my own fault... I would leave the damn door open like a schmuck while running BLC through my lines or something so it would warm up and suck all sorts of moisture in...

For normal course of bidniz... I have the compressor on my window AC unit (which is vented into the house) wired to a simple thermostat and then the fan on the unit runs 24/7 (and has been for about two years now).

If the walk-in warms up, the compressor kicks on... and then if the coils get any frost (and that would only be if I had the door open again or something) the frost melts instantly when the compressor shuts off and the fans runs with the 38 degree air from the cooler.

Works great.
 
So is there a problem with sheet rock on the exterior?

Is HDF the same thing they make peg board out of?

My construction - so far - is 2x6 frame with insulation between, craft paper vapor barrier on the interior. I have not put any vapor barrier on the exterior. The floor is from floor up, concrete slab, 2x6 frame with insulation fill, craft paper vapor barrier, 6 mil plastic, 3/4" chip board/plywood (whatever it is they call that stuff).
 
Shouldn't be any problem with rock on the exterior, you don't have the conditions on the outside for condensation to form. If the insulation is working, the cold air should never get through the insulation to meet at the outside of the wall. Even if any did, the air's so dry that any moisture would evaporate almost immediately anyway.
 
You definitely should have had a vapor barrier between your studs and the cement floor. Since you are in NM you might be OK but ground moisture is a problem and unless you have a very good vapor barrier under your cement the cold will make condensation more likely from any moisture you do have in the cement. The air inside the cooler is dehumidified by the A/C unit so it is unlikely to mold.

According to weatherunderground.com the dew point in Albuquerque is 41 degrees. (Sorry, Corrales wasn't in the system) This means that if you have outside air against one of the walls or the floor as it makes its way through the insulation and wood before it hits the vapor barrier it will start to condense at 41 degrees. This is why you want the vapor barrier on the outside of the walls, so you don't have the moister air contacting the wood and insulation where it can mold. You should be perfectly fine on the interior walls as they will be facing air that is already dehumidified.

If you have a good vapor barrier you shouldn't need green board on the outside as it shouldn't get cold enough on the far side to cause condensation. on the inside I do like the flexible plastic sheets or stainless. Seal the edges well. This makes for a much easier to clean surface. If you use the plastic or thin metal and you have studs inside right now you can add 1/2" foam insulation panels as a backer and increase your R-value further.
 
OSB was/is on sale @ HD. About 6.50 per 4'x8' sheet and it's used as exterior sheathing so the cold inside should not be a problem.
 

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