In all my research, I have yet to find any advice on maintaining a wine cellar that is approximately 55 F and 70% humidity. Most discussions of home insulation assume an interior condition of 72 F and 50% humity. Climate-wise, I am in the San Francisco Bay Area. My house foundation is slab on grade. The existing crawl space is 4 ft tall and ventilated to the outside. The crawl space has a concrete floor. I think it would be an excellent place for a passive wine cellar with some improvements to the insulation to keep the temperature more constant and maybe some vapor barrier to maintain some humidity.
All of the studs are currently exposed on the crawlspace/cellar side. The ceiling and some of the walls are against the house interior. One wall partially partitions the wine cellar from the crawlspace; this one has black paper and plywood applied to the outside. I am planning to add a wall to complete the partition between the winecellar and the crawlspace, insulate the ceiling and all walls, and finish the interior with greenboard and paint. I am planning to fill the stud bays with batts and go over the studs with rigid foam insulation, which leads to my questions:
- Should I put the rigid foam on the cellar side or the crawlspace side?
- Should I use a low-permeability foam as a vapor barrier?
- If I'm not mistaken, the house interior would be a source of moisture into the wine cellar. Should I attempt to put a vapor barrier on the house side of the interior walls and ceiling, or would that create moisture problems?
- The ceiling joists are 2x6. Would filling the stud bays with batts and foregoing the foam be a high enough R-value between the cellar and the house? I'd rather not lose more head room.
- The existing crawlspace vents would not fall within the wine cellar. Should I seal them up or keep the crawl space ventilated?
I have not determined yet whether humidifying or dehumidifying would be required for the wine cellar. Humity lower than 70% might work in the wine cellar, but if the wine corks are drying out, I might later decide to add some humidity.
Thanks for reading, and I await your response.