Depends where you live--a house with no air conditioning generally won't suffer mold, and neither will one with air conditioning. But spotty air conditioning without something like a dehumidifier will breed mold and warp floors.
A friend of mine has been complaining about his rental's warped kitchen floor and mold (or the fact that mold forms easily). His windows are mostly painted shut. Can you elaborate on this? What kind of a dehumidifier should he look at?
