I just saw this question posted by Foiled Again in another thread, I think it was Adventures in Leak Testing, and it was such a good question, I took the liberty of starting a new thread with it because it never got an answer. when I heard how insidiously surface tension can draw water into unlikely places, I had visions of going crazy chasing and sealing every possible leak and discovering we're living in a vacuum with our own sweat.
So here goes with Foiled Again's question (from 3/2010):
Originally Posted by Foiled Again
The human body gives off two quarts of moisture daily just through breathing. We breathe, shower, cook, and occasionally sweat inside our airstreams - and THAT moisture has to go somewhere. I have the bare aluminum walls inside. They are NOT sealed at the seams and they are applied with POP rivets that have teensy holes in the center. So internal moisture that is not vented out can make it's way between the walls and into the fiberglass insulation. I'm sure that even if one has the "mouse fur" interior, moisture can accumulate in the mouse fur as well as migrate through the interior aluminum seams.
It seems to me that it might not be a bad idea to have the bottom side of the windows leak air - or for air/moisture to be able to evaporate from the bottom of the centerline seam. If you think about it, wouldn't it actually make good sense to have a "drip edge" where the floor meets the walls that dripped moisture outward and downward below the exterior band that conceals the rivets?
I am once again chasing a phantom leak near my rear wraparound windows, but when I seal my window frames, should I really seal the bottom once I've gone around the radius? I'd rather have capillary action vent that water OUT than just let it proceed to the floor.
HOWEVER - by not sealing the bottom edges, is it possible that eastern Virginia's well known high humidity is seeping IN between the walls - and what happens when I run my Air conditioner on a 99 degree day with 99% humidity. I see the outside of the trailer develop sweat, is the same thing happening between the walls?
NOTE, I do always have my bathroom and shower vents open even in 20 degree weather - except when there's a noreaster blowing with 50 MPH winds. This gets rid of a lot of humidity buildup.
I guess my questions then, are:
1) Are there some places we know we shouldn't seal?
2) Or is it more that we just try to seal the places where water is obviously coming in instead of sealing places where it might be coming in? That way we avoid sealing necessary air leaks that help keep the vehicle dry inside.
3) Is there a kind of checklist about the best places to check for water leaks? I know about sewer vents, windows and doors, plastic light covers, Fantastic Fan installations, but are there certain especially troublesome parts of the skin or frame that tend to leak?