Well it looks like this discussion of problem doors is not going to go away so I guess it is time to put my two bits worth in.
(a) First off we have to understand some of the properties of Fiberglass. FG it's self is not a structurally strong product so it must be stiffened and reinforced with embedded plywood, wood frames or metalwork. If any of you ever get the chance to look around boat building, street rod body, shower and bath stall FG plants do it. You will learn a lot and see how they add some sort of stiffening in strategic places. A number of years ago my friend and I built molds (Plugs) to build race car parts and snowmobile skimmers and we embedded wood and metal for strength.
When most of these FG trailers were built back in the 60's and 70's the designers and fabricators were reliying on the bonding of the inner and outer door skins to give these doors enough strengh to not warp. For example, they only used 5 horizontal wood strips in the Boler
door, not for rigidty but to keep the two skins apart, much to my dismay when I opened it up. Time has shown that their theory was faulty. As FG ages it loses it shape and wants to flatten out. Some plastics are what is called in the industry "Memory Plastics" Plexiglass (Acrylics) is one of those. I have blow moulded and stretch moulded Plexi and if it didn't turn out right the first go, I could throw it back in the oven and it would return to a flat sheet.
FG may not be a memory plastic but there is enough evidence that it wants to flatten.
All most every older FG trailer I have seen, the door have flattened towards the bottom.
From comments here it appears the plants have sandwiched other materials in to the doors, many retaining water, quite often due to no drain holes in the bottom.
© The other problem that occurs on these doors is the hinges are bolted directly through the outer skin. As the years go by and the mileage piles up the hinge bolts start to elongate the holes in the skin. Next the door droops and doesn't fit the opening proeprly. Then the drooping and flattening door the weather stripping doesn't seal properly and you have another water problem. Even our Boler
door sagged and it didn't have a lot of miles on it.
(d) Two other things I found with our door, and I believe this applies to most others:
Water leakage through the door latches and the window seal. Ours had nothing to stop water into the door latch. Solved that with a rubber gasket.Our window seal was still good but it was a matter of time before it leaked. All the windows
on removall, the mastic was hard as rock.
(e) Most of the fixes I have seen on this forum are what I would consider bandaid solutions. I am not knocking anyone for trying, just that you may have only solved temporarily.
I am not saying my solution to fixing the door is the way to go but it has definately a big improvement in the fit, strength and sealing of the door. I had anticipated more problems and time involved when I started, but it took not that much time and went much smoother that I anticipated. The thing that took most time was finding the right bonding agent.
So if anyone else whats to tackle it, I will be glad to help with directions. Check out my pics on Webshots.