A family member is building a brand new barn and she's amenable to my idea of makeshift-ing a 4'x4' (or so) closet that would be used primarily for meat ageing (I like to hunt) but also pickling and other similar stuff that a regular fridge is too small for and a restaurant-grade walk-in cooler would be too costly.

The barn is studed up and I can use a corner to implement this idea. The ceiling is high enough to hang even a cow although deer is more likely. I was planning to modify (hack) a regular window AC unit to be able to chill down to 40 deg F, I have heard this is possible and if not, I hear Cabela's sells some kind of conversion kits. The room would be against a wall facing outside so I could make an opening to fit the unit.


  1. Considering it is a makeshift cooler, what insulation should I put?
  2. Will using a regular (laminated) door with a spongy gasket around the perimeter properly seal it from the outside?
  3. Any ideas on how actually difficult it is to modify an AC unit for this purpose?

When not in use, I would like the closet to be modifiable for storage, e.g. have shelf support brackets etc.

  • Nice R-value per inch table here: todayshomeowner.com/insulation-r-value The foams win at about 5.6-8 per inch. Polyurethane foam should be easy to find. – Wayfaring Stranger Oct 16 '17 at 17:50
  • What's a "regular laminated door"? Do you mean a steel exterior door? #3 is vague and a bit off-topic from the rest of the question. You might split it out. – isherwood Oct 16 '17 at 17:59
  • @isherwood -- a door that is sandwiched by smooth countertop-like material to protect the wood from moisture, like MDF, as opposed to a regular paintable door. – amphibient Oct 16 '17 at 18:03
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    i would use an AC with knobs instead of buttons: digital devices will likely have annoying safety sensors. – dandavis Oct 17 '17 at 5:28

I made a locker in my shop using atlas energy shield foil covered foam panels, it was a little larger 6x6 it worked ok the second time I set it up I doubled the insulation because it was in the high 90' s . I used a 8k BTU unit and changed the thermostat to a cheep refrigerator one. The only problem I found is it takes almost 24 hours to get the temp to 36f. And I really need a fan to pull the hot air away from the corner. I used the panels to make the door also. I collapse my room down when not in use. One change for the next time is a track (trolley) down the center so I can run the animal in as it is tough to hang a whole cow in this small area even using a tractor. A deer would be much easier, I did install a 2 tube fluorescent fixture that I converted to LED. Running a window AC unit colder like this can lead to icing but I have not seen this but do check every morning that I have it running. It is a very old R12 unit with a simple stat (not electronic). Note getting the room down to 36 and putting the animal in there the temp did raise up I hang at 38f. But try to get everything pre cooled with the lights off to get it to temp as quickly as possible.

  • have you considered a ratcheted winch lift for a cow ? – amphibient Oct 16 '17 at 20:20

I found a website that actually talks about DIY walk-in coolers. Based on what they say

  1. You want an R value of 25 or more. This will require foam insulation, since fiberglass can retain water. Might be worth putting some rigid foam over top of spray-foam and then foil-taping joints.
  2. They recommend a standard pre-hung exterior metal door. It already has a gasket and they report these work well enough
  3. The real purposes of the site is to sell their device to convert a standard window unit for these purposes. A normal window until won't cool to the temps you need (about 38 degrees F), nor would I suggest trying to modify one to do that. They suggest an 8k BTU unit for a 4' x 4' room

Just assuming the room would actually cool into the 30s it would be extremely hard on the compressor. They just aren’t meant to go much below 70. I have run them at 60 degrees for cheap wine rooms with a different thermostat. They usually last about 2 years. The room needs to be completely sealed with a vapor barrier or you will have condensation issues. There is no way to seal a window unit, they just aren’t made that way. I am sceptical if you could get it down into the 30’s but if you could you would have condensation issues and the unit wouldn’t last very long. If you are willing to put up with those pitfalls then it is doable.

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