Only a year ago, I inherited 1/2 of a duplex in Florida. Both my unit and that of my neighbor has a clay tiled roof. This is a single-story ranch, 2-bedroom, two bath home, with a small attic above the entire unit. About six months ago, water stains started to appear in almost every room of the home's ceiling (except kitchen, bathrooms, closets, and laundry). All stains have appeared in ceiling areas nearest outer walls, with a couple of exceptions: there is a stain in one bedroom ceiling that isn't on the outside wall (but it isn't exactly in the middle of the room either); and another stain has appeared adjacent to a ceiling vent in the foyer. A number of roofers have looked at the problem and all are quick to want to replace the roof. However, having known the previous owner, I know the roof is not old and shouldn't need to be replaced. Further, I can't replace the roof because my neighbor insists he has no leaks in his unit and is unwilling to replace his roof (HOA requires a new roof on both units for an exact match). A personal inspection in attic has revelaed no leaks in the roof and the lumber flooring found in various parts of the attic are not wet. There is no visible presence of water or water beads or dripping water anywhere. Nonetheless, it seems as if there is some condensation in the air . . . coming from somewhere. There are vents under the eaves of the home, around the full perimeter of the house, and the home is air conditioned, with an air handler located in the attic. I'm not sure the problem is the roof so, I'm seeking thoughts and ideas on what other problems might cause ceiling leaks (besides the roof) . . . and possible next steps? Thanks, in advance, for any response.