Walk in cooler insulation

[summerofgeorge]

I'm finally looking to get back on track with my basement brewery and was hoping to get some help on what I might need to do for a walk in cooler. Before I design the entire area, I wanted to get an idea of what it might take (cost/time/effort) to include a walk in cooler.

My brewery space is currently a storage room in my basement. The walls are cinder blocks and are insulated/drywalled. The floor is currently an unfinished slab. One wall is shared with the rest of the basement, but since the brewing area was part of an addition, the shared wall is the exterior block wall from the original basement. So 3 outside walls are block, stud/insulation, drywall. The shared wall starting in the brewing area is drywall, stud, block, stud/insulation, drywall.

I've read that I should shoot for R-25 overall for the walls. What I'm trying to figure out is what additional insulation I would need depending on which wall(s) I use. I also don't know what I need to do about vapor barriers, if anything. The last thing I want is to deal with mold issues. Any help is greatly appreciated. I've read about other builds but they seem to be standalone rooms or don't address working with the existing insulation.

 

[Dr_Jeff]

Since it is in a basement, the "exterior walls" are underground, correct?
That should be plenty of insulation.

 

[summerofgeorge]

Exterior walls are almost entirely underground. Maybe 1' above ground but I'll probably have a lower ceiling in the walk in to avoid having wasted space at the top to cool. I would assume I still need to add insulation to the exterior walls? And possibly a barrier? I really want to avoid any mold issues.

 

[orono]

IMO, the type of insulation in the walls will be a factor in your concern of mold. You should determine if it is batt insulation or rigid. If it is rigid, hope it's closed cell. If it is batt, you'll definitely want a vapor barrier (between the exterior wall and your interior wall) although you'll want to pay specific attention to "trapping moisture between these barriers (from condensation of temperature differentials and thermal bridging). If it's a block wall, depending on age of the wall, it most likely isn't a cinder block wall. It will be cementitious based. Block walls can be your friend because of the cores in the blocks. Rigid insulation with foil coverings can be used a vaper and moisture barrier if it was installed correctly (joints taped, and snuggly fit with no air gaps). Your slab should work great with out having to incur any additional costs. The door system you choose to use should be given good consideration, too. When I built my walk-in-cooler, I used 5.5" of rigid insulation between 2x6 framing. I used a CoolBot for cooling - it worked great with the caveat that the darn fan ran 24/7 and dripped water.

 

[summerofgeorge]

The insulation in the exterior walls is batt. Two of the walls are new (2016) and the other two are older (1993).

Could I use rigid insulation with foil right against the drywall that has the batt? So block wall | batt | drywall | rigid? If so, how thick would the rigid need to be if I'm underground? If it needs to be ~5", that's fine but I'd rather not go overboard if I don't need to.

 

[orono]

Short answer is yes you should be able to use foil faced insulation directly against the existing sheetrock. Make sure you tape the seams. Maybe you can recall if your existing sheetrocked wall has poly (plastic)? Remember any moisture generated or inherent will need to "go somewhere." Take caution with your ceiling, too. Remember that condensation forms when warm moist air contacts a cool surface (when vapor turns in to liquid). As I mentioned any moisture generated or inherent has to go somewhere - try to keep it out of your walls and ceilings. It will be much easier to deal with on your concrete floor.

2" of foil faced insulation will be more than enough considering you already have batt insulation in that (those) wall(s). The reason I went with 5.5" was that I started new and used 2x6 framing lumber. Being underground doesn't really come into this consideration for thermal properties - only for moisture considerations.

 

[Jacob_Marley]

For a walk-in that functions comparably to a commercial walk-in, the money is in the refrigeration (condensing unit and location etc) cost, and efficiency. Roughly, figure a standard commercial grade 8 X 8 X 8 walk-in freezer uses about 8,000 kWh per year in electricity ... that's about $1300/yr (at my residential rate of .1528cents per kWh.)