Cold room tune-up

Q: What can I do to even out the temperature in the cold room under the concrete porch of my eight-year-old house? I’m using it to store "you-brew" wine and the temperature varies between 0C and 18C over the course of a year. That’s way too much for wine. There’s also lots of white, fluffy efflorescence on the walls and the wood framework on the ceiling that I’d like to remove. What should I do?

A: I get more questions about basement cold rooms than any other single home-related issue. That tells me that people still want good cold rooms these days, though designs have changed and performance is rarely what it used to be. If the wood on the ceiling of your cold room is the kind of lightweight framing material that I suspect it is, then yes, you can remove it. In fact, you should. Just be sure to have a carpenter come in first and take a look. Removal is best because wood can trap condensation and promote rot and mold if left in place. Like most second-rate cold room’s, you've got two main problems: the white fuzzy efflorescence on your walls, and widely variable seasonal temperatures. Efflorescence is caused by small amounts of moisture wicking in through the concrete, bringing minerals with it. As this water dries, dry minerals are left behind in a fluffy, mold-like form. Efflorescence is harmless, but ugly. A waterproof basement coating (Drylok is currently my favourite) will stop the moisture migration and the problem. As for evening out temperatures, here’s a plan. Start by applying sheets of 2-inch-thick extruded polystyrene foam to two surfaces: the ceiling of your cold room and the inside face of the door. This foam needs to be covered to meet code requirements for fire safety, but it's worth the trouble. Just be sure to fasten the foam with beads of construction adhesive that both crisscross the sheet and circumnavigate the edges. This prevents warm, moist indoor air from sneaking in behind the foam, cooling there and condensing. Monitor temperature levels, then add more foam to the top of exterior cold room walls if wintertime temps still drop too low. You might also consider an operable vent to allow outdoor air inside when conditions permit.