1963 Pathfinder 20'

Welcome to VTT.

Unfortunately, all the caulk and sealants in the world will not stop a trailer from leaking. It causes many bad words when dismantling for repairs, too.

The main leaks are caused by bad putty and bad metal. Some roof metal is so bad that you can see pin holes when looking from underneath. I've even found pinholes in butt metal.

Putty on the J rail (edge trim) dries out over time. Then the freeze/thaw cycle enlarges tiny gaps into large ones. This is the main cause of leaks in a trailer. Water follows the path of least resistance and travels inside the walls, settling at the sills and floor joist. Rot follows.

Windows, roof vents/protrusions, doors and exterior access items should all have new putty. Anything that penetrates the skin. One cause of failed new putty is bad wood behind the trim, window, door, etc. When the wood is bad, the screws can not grip to ooze the putty to form a seal. So new putty alone will not form a seal, thus all framing wood must be in good condition.

I suspect your metal may be compromised but it's hard to know. If you see little "bubbles" signifying rot in the metal, it's certainly possible there are pinholes as well. The roof can be a culprit. Inspection doesn't always show damage but it is worth it to take a very close look at the roof and siding.

To repair your trailer, the metal must be removed and the roof either floated or also removed. Repairs should be made to all wood framing with a careful eye on the sills and floor joists. Once the wood is sound, your metal and roof can be re-attached.

As far as new metal, it costs about 2500 for a 15 foot trailer, possibly 3 to 35 for a 20 footer. Shipping is the killer when buying aluminum. New metal alone won't stop the leaks but it's a good finish.

Check out Larry's videos here: cannedhamtrailers.com/ He has a ton of repair videos showing how to do them.

Here is my book: vintagetrailerrepairmanual.weebly.com/ It describes the order of build with many photos of the process.

We are all here to help. Please post some pictures for us and ask questions.

Thanks so much!! yes I get it and thought of that.  The metal on this trailer is fine; so is the framing.  I am sure the floor framing is semi-compromised where the water has settled in the past; however as it was covered for most of it's life; it has not done the damage that would cause the skin to not attach.  It came from Spokane; and lived in that area its whole life under a shed roof.  We pulled it back to NY and as soon as we arrived and parked it- and it POURED RAIN, we realized the problem when every opening in the roof allowed water in.  So we opened up the ceiling removing damaged plywood, insulation etc and reinforced for a roof AC; replaced it and did NOT remove the roof to do so.  Before you scream at us.....

We are tin can tourists and love our buddy Tim Heintz from Panama City FLA (master trailer man); who has consulted on this with me alot.... He blessed the AC set up -although the right way would have been to remove the skin.  We did it from inside - worked great and my roof is the only thing not leaking on this baby.  Anyway; we are mechanics (husband rebuilds engines; has owned about 25 muscle cars- I can tune a slant 6), and builders (we have remodeled 3 houses) so slightly ahead of the curve with this stuff.  I am happy to pay someone to re-skin (we can't do it; don't have a big enough garage) but would have to know it will NEVER leak again to make that investment.  

Anyway... I did lift the aluminum side trim where the two sides end on the corner of the trailer; and replaced that putty as well.  I then added clear silicone to the edges of that trim and have greatly reduced but not STOPPED the water.  Thought if I peel up the skin on the end of the trailer; use spray foam insulation and some kind of vapor barrier for the back of the plywood panel maybe the water can run in and out; and the spray foam insulation doesn't care; and the barrier protects the plywood.  What do you think of that idea?  Or if I peel up the back skin is it impossible to get it back in place?