I sense that this may be a loaded question because there are so many factors involved. What would the life span of a properly maintained coach be? I understand there are so many different manufa...
Leaks and delamination will be the biggest causes of short life. Leaks can be controlled (never allowed to happen in the first place), delamination sometimes cannot.
Keep them sealed up and they'll last a lifetime, unless they come unglued.
Our current coach is 8 years old, looks 100% like new.