by Tomterrific » Sun Apr 19, 2020 11:36 am
The photo will not show damage. The front is covered with aluminum foil faced butyl flashing. The damage was first noticed years ago when I saw small paint bubbles. The paint and primer is oil based. The paint was scraped and another coat of Rustoleum white was added to the front. Eventually I added the flashing. I noticed soft spots under the flashing this spring.
I'll give my thoughts as Tony seems interested. I have a hobby with old motorcycles. Gas tank rust is a problem. The tank breathes through the vent with a change in temperature. Ohio is a wet state with daily temperature fluctuations. These motorcycle tanks can capture surprising moisture over one winter let alone several years of sitting. My camper sits outside and I believe the air space, although small, has captured enough moisture to wet the lower cheap Styrofoam leading to the soft spots.
My suggestion to future builders is:
Use extruded insulation board, not the expanded Styrofoam like I did. I found boat building sites saying the expanded foam will hold water.
Do not leave any air space between the roof and ceiling to trap moisture from breathing due to temperature change.
Place vents inside at each of the lower spaces so moisture can escape. Something I should have done when I first noticed this.
I still don't know why I have this problem. The flashing has the face of the ply absolutely water tight.
Tt