DIY walk in cooler using Coolbot or similar control

I have tried using the search button on the Coolbot and not seen what I am looking for.

The recommendation is R25 using foam board insulation for all walls. If I build an 8'x8' walk in cooler, that would require QTY 12-4'x8' sheets of foam per layer. If I am to achieve R25 and a 1" XPS board is R5 steady, at $30 per board, 12 sheets for 1 layer x 5 layers to achieve R25 = $1,800 in just insulation. I have to figure out how to attach 5" of insulation plus framing, door, ac etc.

Are there any alternative insulation methods to achieve this R25 that will withstand the potential moisture issues? I don't have to worry about big brother looking at it.

Edit-I could go smaller, maybe 4'x8' or 4'x4'. I would like to hang deer and other animals to age the meat before butchering as well as storing canned goods, dry herbs, etc. 4'x4' would be pretty tight for a decent sized hanging animal.

You could use 1/2 extruded polystyrene foam board Insulation as the inner panels of the room.
They are only R3, I think, but they are advertised as impervious to water.
That's about $182 for 13 sheets at Menards.
The 13 sheet is to create strips that go on the face of the studs.
That will cut into thermal bridging.
You could use adhesive and skip the screws, since the insulation board is light .
If you do skip the screws, be sure to also  use free standing shelves that don't need to be screwed to the walls.

You could use R23 Rockwool in-between the studs.
Going off Menards prices that should be $800 for 16 packages.
Rockwool can get wet ,then dry out and still be insulative.




I would probably use the sheets but fill the wall cavity with Styrofoam waste.
For cladding you could cut up an old fridge and screw the panels to your studs, sealing the cracks with expanding foam.
That will look terrible but it should work pretty well.
You could actually build your entire structure from old refrigerators, including the foundation .
But that's a lot of bootleg for a project that you need to work.

William Bronson wrote:You could use 1/2 extruded polystyrene foam board Insulation as the inner panels of the room.
They are only R3, I think, but they are advertised as impervious to water.
That's about $182 for 13 sheets at Menards.
The 13 sheet is to create strips that go on the face of the studs.
That will cut into thermal bridging.
You could use adhesive and skip the screws, since the insulation board is light .
If you do skip the screws, be sure to also  use free standing shelves that don't need to be screwed to the walls.

You could use R23 Rockwool in-between the studs.
Going off Menards prices that should be $800 for 16 packages.
Rockwool can get wet ,then dry out and still be insulative.




I would probably use the sheets but fill the wall cavity with Styrofoam waste.
For cladding you could cut up an old fridge and screw the panels to your studs, sealing the cracks with expanding foam.
That will look terrible but it should work pretty well.
You could actually build your entire structure from old refrigerators, including the foundation .
But that's a lot of bootleg for a project that you need to work.

I looked up the R23 rockwool. Thank you for the suggestions as I will frame with 2x6. The coolbot's publication mention it as a possible insulation that resists mold/mildew.

We do not have Menards in the south but I can get a 2" R-10 4'x8' for $45 so that cuts the price down quite a bit verses the 1" R-5.

more natural options that I know of that handle moisture well: wool, cattail down, cork.

only really viable if you can harvest and process them yourself. or, in the case of cork, all the stacks of cash you have laying around are really starting to cramp your space. though I guess if you have a wine habit and a lot of time on your hands, that one could be “gathered,” too.

also lower R-values/depth than the more conventional options, so you would eat into your available space to get comparable insulation.

the cattail down and wool would need some sort of treatment to keep bugs out. cattail down would probably need something to address flammability, though the bug treatment might help with that, too.

I’m sure there are plenty of other equally or more impractical options. light clay and millet straw or russian olive woodchips? daikon charcoal in clamshell lime plaster? sky’s the limit, really.