I am also in N. Virgina (Arlington) in a cape cod style house built in the late 40's. I finished our basement 2 years ago. It went from a dark mildly musty space to what's now a nice cozy dry one. Among the work, I first had several foundation cracks filled with urethane ("crack team"). I also regraded to allow the 3 day rainstorm runoff that we get often enough (couple times every year!) to go elsewhere instead of pooling next to the foundation and finding it's way in. Also added a second downspout out front (if one spout gets blocked by oak leaves in the middle of a storm, the water still can flow without running over the gutters down to the wall). As for insulation of the walls, first I went around the inside perimeter (rim joist area) and sealed every last air gap with caulk, etc. and then applied solid pieces of foam in each space, followed by spray insulation around the edges. Very much a pain, but the results were worth it. (another option would have been to get a contractor to apply spray foam up there entirely...along with the walls - (next time I might do that instead). Then I used 3/4" XPS on the walls. I glued it with foam adhesive, but supposedly you're supposed to fasten it mechanically. Anyway, all XPS joints between panels were taped ("tuck tape"). Then I framed the walls and used unfaced insulation in the wall cavities for some extra R value. As I said, the result has been nice and dry and cozy (or nice and cool and dry in the summer). We had a brief problem this summer when a downspout elbow came loose, allowing water to deluge the nearby window well and enter the basement through the window frame. Still, it dried out fine (humidifier) and there is absolutely no sign of moisture odor down there. ( I imagine the water flowed down the back of the XPS, so the fiberglass insulation never got wet.) BTW, we left the floor unfinished (only painted) and kept the floor drain to see how things would hold up. Happy with that decision, as well. After a couple more years experience under our belts we might feel confident to finish the floor, but it's fine without thus far. It all sounds like a pain, but the results were well worth it. No mustiness whatsoever.

When one sets out to build a custom home they should be limited solely to their dreams and budget constraints. If they want a wine cellar so be it, and if the neighbor wants a conference room to host AA meetings that is thier choice. I once did the plumbing in a house that had four bedrooms but 6 full baths and three 1/2 baths and only two people live in the house. Personally i thought it was a bit too much, but far be it from me to tell the next man or woman how to build their dreamhouse. What truely amazes me is the number of people who are designing their dream house, then post on the forum asking the opinions of others as to whether they should have a certain feature or not? The whole idea of a custom home is to create an enviroment that befits your personal lifestyle and interests. In my personal opinion if a guest drops by and don't like your choices they have the option of going back to their little corner of the world where things are done their way. If a wine cellar complete with a tasting bar befits your social habits then by all means that is what you should have, just don't forget an adequate storage facility for the cheese to be served with the wine.

I've built two wine cellars. One at 800 or so bottles and one at over 3000 bottles. Insulation is the first step. Part of that insulation issue is the VAPOR BARRIER. Remember your cellar will be COOLER than the other rooms in the house (including those overhead), that adjoin it. The vapor barrier goes on the warm side. If you're insulating from the inside of the cellar it means you'll have to wrap plastic around the studs/joists following the surface of the outside wall, then insulate. In my small "closet" one, I just used fiberglass batts after the plastic vapor barrier. I finished the inside with the new paperless drywall. The sad story is that most small wine room chillers are junk. I've got a Breezeaire which has failed twice already (the first unit went back, and the second after about six months the thermostat stuck on). Some talk about taking a regular window unit AC and hacking the thing to run cold enough, but that seemed a bit too experimental for me. A good thing to have is a little indoor/outdoor thermometer (get one that can measure outdoor humity). Shove the outside probe through the wall so it is measuring the cellar and leave the display somewhere you will see it from time to time when you walk by. I made an insulated door by taking a standard home center interior door (my door is only 24" wide) and cut out the interior "luaun" skin and scraped out all the cardboard spacers. This now gives you an 1" door "frame" and the outside skin. I put a 2" sheet of rigid insulation in there and then capped it with a skin of Luaun ply cut down to fit. Lots of spray adhesive and a few screws hold it together. The other cellar, I had spray foamed (since the house was getting it anyhow) and has an exterior door. Since it is a larger space, I have a small split system (like a regular house central air) that's commercially designed to run down to 55 degrees (I keep it at 57). Of course, racking can be as simple or elaborate as you are willing to pay for or build yourself. My small cellar has simple rectangular bins each holding about 12 bottles made out of plywood. The big cellar has custom redwood racking. So give us an idea of what the space is, where it is, and how big it will be.

You are going to have a lot of problems. You're sealing the concrete wall with the insulation? "I started with 1 layer of the 4” XPS over the ceiling and then covered all the walls with 1 layer of 4” XPS foam leaving 1’ of bare concrete at the floor on the exterior North and East walls)." What's on the other side of the concrete? Dirt? Or is it an attached house like a row house? If it's a detached house and it's just dirt on the other side, which seems to be the case because you said it extends 7 ft below grade, you will have a great deal of condensation and eventually mold. The concrete walls are not completely dry and sealing them the way you did allows no place for the moisture to go. Don't seal those walls off. "As for venting, no. It is a fully inclosed concrete box. Monitored humidity is a constant 70%." So the ceiling is concrete too and your entry stairs are over that? If so, no wonder you have condensation. On the other hand, you have the makings of a great wine cellar. I wish I had that. Depending on where you are, the soil temperature can vary quite a bit between winter and summer but you're in a cool area so you should be fine. If you have 70 percent humidity in the concrete room, why are you insulating with a vapor-proof material and then sealing off all possible avenues for the moisture to escape? You can't do that. What happens to the temperatures if you don't seal the ceiling and concrete walls and just insulate the walls exposed to the basement? I think you'd be far better off with that approach. If the concrete walls give you a stable temp, why insulate them? Also - the door is R10 and the rest of the insulation is R20? If you really want R20, put insulation on the door too. Otherwise, you have a huge section of your wall that has a lower R value than everything else and you will effectively have insulation of R10. To start, I would take down the insulation from the concrete and monitor the resulting temp in the room. It seems like you can actually get a pretty good temperature and perfect humidity with what you have, doing minimal work. Good luck.