Advice on building a small wine room/cellar

For the past few weeks I’ve been mining old threads for tips on converting a storage room in my basement into a small wine cellar, and the information I’ve found here has been incredibly helpful. Thank you! That said, I have a few specific questions I was hoping to bounce off the forum. For context, I am located in the Hudson Valley, NY and am hoping to store a modest collection of 200-300 bottles. My goal is to achieve storage conditions that are “good enough,” so I’m not aiming for the highest tier of professional-grade standards or anything like that. The room is roughly 4’ x 6.5’ and sits below grade except the top foot or so. The room juts out from the general basement floorplan (the room actually sits beneath a concrete front porch) and is surrounded by earth on its 3 exterior sides. Those 3 exterior walls, as well as the ceiling, are covered with thick spongy foam board that must have been installed by the original owners. The r-value is probably not that high, though the material does seem to provide some insulation as I monitored the temperature all winter long and the lowest it reached in the room was around 43 degrees, even when outside temps dipped into the teens. The floor is concrete, as is the wall facing the basement that you enter through. I’ve included some pictures below that hopefully provide a decent overview of the space. My questions are as follows:

  1. Ideally, I am hoping I can create a suitable environment for a passive cellar without totally reconstructing the room. I already filled the joints in the existing foam with some spray-can foam and covered it in foil tape. The next step in my plan is to add r-10 foil-facing rigid foam board insulation to the 3 exterior walls and ceiling. I figure this additional insulation may be enough to get the walls close to an r-15 value or more, when you take into account the foam that’s already in place. For the concrete parts of the entry wall, I am planning to add r-15 foam board insulation. And, of course, I am replacing the entry door with an insulated exterior-grade door and weather-stripping. Does this sound sufficient for purposes of insulation, or am I missing or underestimating anything here?

  2. Is there anything I need to do with the concrete floor besides seal it? A primary concern is that when it rains, dampness appears to accumulate and seep through the floor in the corners (as you may be able to see in the pictures). There are never any puddles, just some floor dampness, but I’m wondering whether any remediation is needed (beyond sealing the floor) to prevent mold growth.

  3. Relatedly, the room currently maintains a high humidity. I’ve monitored and it typically hovers between 70 and 90%, and is actually more humid than the rest of the basement. My understanding is that the foil-facing rigid foam should serve as a vapor barrier, and so I’m hoping once it’s in place the humidity will reduce to around 50-70%. Is that a reasonable expectation or will I have to plan for additional steps to control humidity, e.g. a dehumidifier?

Apologies for the long first post, but any guidance would be deeply appreciated. Thanks again!

I think you’ll be fine. I have something similar in my crawlspace to handle excess. I personally wouldn’t seal the floor, just add some floor tiles (I use dollar store puzzle mats cut to size) to keep a bit of damp off any cases you stack and for comfort and/or security, should a bottle drop.
Gold’s book “how & why to build a wine cellar” is ideal in your case as it is a basement and you won’t be using mechanical cooling. Keys are vapour barrier against the outside walls where possible and stagger your R-values as you drop below grade. Highest on the ceiling, a bit less on the walls, and little to none on the floor. Mine at a similar latitude in Southern Ontario gradually moves from 53f late winter to 63f late summer. I do pipe some home a/c in there from time to time during the hottest weeks just to supplement slightly and keep the humidity within reason. Have used this for 16 years without issue. The outside of bottles aren’t quite as pristine as my active cellar due to higher summer humidity, but apart from needing to wipe the cork once the capsule is cut before opening, no difference to the wines themselves.

Thanks so much! I’ve actually consulted that book you mention, based on recommendations I found here. Out of curiosity, any particular reason you would not seal the floor? Is it because an unsealed floor will contribute to a better humidity level? Oddly enough, in researching cellar builds, it’s the one thing I’ve seen divergent opinions on. Some sources insist that sealing is necessary while other sources say the opposite.

I would rather have 1 (the lowest) surface of a passive cellar be somewhat permeable. If air conditioned you wouldn’t as the unit would assist with keeping appropriate humidity/ moisture levels, but without you may get a spike in the small space which then has nowhere to go.

Agree w Chris about not sealing the floor.
In my exp, water ingress in old basements comes through the walls which are already covered in your case, not the floor. I’d seal the walls if possible & leave the floor alone. (Would require taking the spongy insulation off).
Sealing the floor would just serve to trap the water in the room, produce standing water and make the humidity higher, imo.

Thanks, I appreciate the responses and I’m glad I asked the community. I think I’ll go ahead and insulate but leave the floor unsealed for now, and just monitor temp and humidity for a while before moving my bottles in.

I used something called “Dricore” as subflooring (over which I put engineered cork flooring). Just the dricore panels could help because they have airspace on the bottom so that nothing is sitting in any moisture and it can escape (you leave about 3/4" around the edges at the walls). I believe there are comparable products - Dricore is sold at Home Depot or Lowes, and the similar one is sold at the other (IIRC).

What is the current wall insulation made of? I might consider taking it off and installing plain foam panels instead - some older insulation panels don’t take to moisture well.