Originally Posted by Mr Havercamp
I would not use any car or truck wash, or anything else, that uses more pressure than a normal garden hose on a TT or any RV. You're playing with fire. Forget the decals thats the least of the concern. You'll blow water past things like vinyl snap trim at corners and those screws underneath it are usually sealed poorly. When they put roof membrane on they let it hang over the side, then they attach the awning or gutter rail over it by screwing it through the membrane. Then its trimmed off underneath the rail. They do not caulk the underneath just in case water did get in from above it can drain out without laying behind the rail. Wait and see what happens when the high pressure water blows into that area from below.
Right On Mr. Havercamp !!!
I do some times use my little power washer,,, with a very fine spray,,,
and @ a safe distant !!! I have a garden sprayer that is almost 4 ft long that works real well !!!