Q. We have something growing behind our refrigerator. The crust crumbles when touched. The back of the refrigerator is dry. When it creeps out to the other side of the wood partition we wipe it up, but it keeps coming back. Any ideas?
It seems as if moisture and mold, which comes in many colors including the black, are deteriorating the plasterboard. The moisture is caused by water vapor condensing in a tight enclosure. To fix it, replace that section of plasterboard and paint it, then pull the refrigerator out to provide more air circulation. Make sure there is good space under the fridge and above it as well as to the sides.
Q. I bought a home that has a partially finished basement with carpeting directly on the slab. There are two dehumidifiers. No moisture was noted. What should be placed on the slab before any type of flooring, and what flooring is best?
There is nothing you can put on a basement floor that will stop water vapor, except a 6 ml polyethylene vapor barrier under the slab. Since that is not practical, you can continue with carpet and dehumidifiers, which must run in still air (no ventilation).
Since no moisture is detected, shut down one dehumidifier. If no more moisture is detected, shut down the other, and use one only when needed. You could use ventilation instead to keep the basement dry and stop using dehumidifiers. (Avoid venting in hot, humid weather.) The best flooring on a concrete slab is ceramic tiles.
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