Puzzling Pattern on Ceiling

[richp]

Hi,

My 2014 Silverback 33RL has been a pretty good unit overall, and I have been diligent about exterior roof inspections; there are no signs whatsoever of leaks.

However, today I noticed a uniform pattern of shaded lines on the entire length of the interior ceiling, which almost certainly reflects the metal joist pattern in the roof itself. The attached photo shows them as faint gray parallel lines.

No telling how long they have been there. But I didn't see them in the extensive use we gave it last year. I just travelled down from Illinois to Gulf Shores last week for the winter.

I sure would like to know if anyone else has experienced something like this, and if they reached a conclusion about what it means.

Thanks in advance.

Rich Phillips

[Flybob]

If there is humidity inside and it is cold outside, you can get some condensation along the beams. I could be temporary moisture, or a mark form repeated condensation.

[richp]

Hi Flybob,

That occurred to me as well.

It was not all that cold when I left home, and the trailer was unheated until I was about 400 miles south. The rest of the trip here, it was rainy and humid, but temps were moderate. It doesn't meet what I understand to be the usual profile for excess inside humidity, but I concede that is a high probability route to an explanation.

Rich Phillips