I live in Dublin, CA (25 miles East of San Francisco). I have a great room with an open-beam ceiling about 16 feet high. In the summer, when all the windows are closed and usually when the air conditioning is on, condensation will form on the beams and drip to the carpet. You can see small amounts of mildew on the wood beams (Not bare wood, though. The ceiling is painted white). Common sense tells me that this can't be good for the ceiling beams or the carpet, but I'm not sure what to do about it.