[Chuck v]

Johnny Boy,

I don't know what the differences may be between my 2007 Tour Master and your same year Crescendo, but mold or a black stain on the ceiling panel is not a good thing. Good ventilation is essential for any coach to avoid mold, but the real risk is an actual leak.

I had a small drip that came out my ceiling light that at first was thought to be condensation but was traced to a failure in calking on the roof itself and water finding a direct path in. Renewing the sealant/calking was the remedy.

The roof sealants used around the skylights, fan/vent openings, plumbing vents, satellite dish, and any other roof penetration only last so long and need to be inspected and redone regularly as needed. Your coach is a decade old, and if it has never been garaged nor resealed it is long overdue. Perhaps you can inspect it your self easily since it is in an area that can be viewed readily from the rear ladder and doesn't necessarily need you to get up onto the roof itself. While you may not find the offending leak, you can see how the sealants are aging/performing and take appropriate action.

Since my own leak was believed to have been very short term I did not see any staining, but was concerned about retained moisture and mold occurring in the insulated space between the structural roof and the ceiling of the coach. My solution/insurance against this was as follows:
1. take down the fluorescent fixtures along the mid line of the ceiling in the walk-in closet, the bedroom and the hall.
2. inspect for any trapped moisture in the foam backing of the ceiling vinyl and/or above the thin plywood into the rigid foam insulation.
3. add a small DC "biscuit" fan at the wire access hole of two of the light fixtures and sandwich them in place by remounting the fixtures. The fixture now sits about one and a half inches off the surface of the ceiling, but you cannot see the fan back at the center of the fixture...

These small fans only move a few CFM of air per minute and are very quiet, so I let them run anytime the lights are on. This ensured that any trapped moisture in the ceiling area was vented/expelled into the living space where normal heating & ventilating would properly dissipate it. I had planned to have these two fans in place just for a few weeks after I found and fixed the leak -- but I have not gotten around to removing them yet and I see no harm in leaving them there for the time being. It has been several months.

Sorry for the long post -- hope it helps.

Chuck