C Channel - Floor - Famous Rear Bumper Leak

[Soyboy]

Last night I noticed I have the dreaded rear floor rot due to water intrusion under the trim strip at the rear bumper (1999 Safari). This is in the rear trunk. it is a fairly small area along the back between the door and the curb site. Some of the wood is still intact, well I guess it all was "intact" until I pulled the rug up, but there is an area maybe 8" square that fell through and is laying in the belly pan on top of the insulation. I have pulled the rug back and I am hoping for some dryer (read lower humidity for those that don't live in the D.C. area) weather so it will dry out.

Still on the fence about repairing. Most of the wood in the trunk is in good shape. I might try to stabilize the rotting area with some Rot Doctor, and then patch the totally rotted piece., although, I think if I take out the curbside twin bed, I likely can replace the whole bad area, which of course would make the best repair. I am hoping not to have to fool with pealing back the sidewall but I will have to see what that is all about (yes I have read many threads about this repair).

Yes I do plan on pulling of the rubrail in the back and sealing along the bottom between the Alum and the wood floor that is STUPIDLY exposed (after all these years, this should have been re-engineered, folks on here have already done the design work from what I have seen. A simple fix, but that is THOR for you). I guess I should use Parbond for this? Others recommend Vulkum. Why not Sikiflex (sp)? I understand the rub rail is riveted on, I will have to find out what rivets are best to use. I do have a rivet tool. Also, when re-installing the rub rail to you just put it against the skin or does it have butyl/whatever between it and the skin?

Anyway, being new to Airstreams and not having torn one apart YET, I want to try to understand the "C" Channel. I always thought the C channel was a piece of alum at the bottom of the skin that the plywood/OSB slid into. Then "wrapping" around the floor on 3 sides. However, I have read threads where the C channel rests on top of the floor. Is the purpose of the C channel then just to support the sides and give a point of attachment to the elevator bolts? If the floor does not fit into the C channel, what is one sliding the plywood into when installing the new pieces? It would seem that if it is not in the C Channel, then it is basically exposed behind the rub rail all the way around the trailer. That seems dumb. I'm confused.

I also understand on a patch job that one would want to sort our where the elevator bolts are and cut notches in the wood so you can slide it in around them. Is that correct? You then fasten the wood down to the frame using flat head screws? Folks also seem to recommend dousing the area with a solvent/epoxy like Rot Doctor, to help prevent future problems. Couldn't one use man made "decking" of some sort to patch this instead of plywood, in order to avoid future rot?

BTW, the piece that is rotting runs completely across the back of the trailer but is only (from memory) 10" or so in diameter. It looks like it has staples joining it to the "main" floor. I wonder if this was repaired before or if this is SOP (not using a full piece all the way to the rear).

[Wabbiteer]

The factory floor sheets are (often?) cross-tied by corrugated joiner strips that bridge the gap between sheets and lock the whole floor assembly into one rigid piece. They are thin steel sharpened on one side and hammered in. Maybe that is what looks like staples?

Patching avoids the slippery slope of finding more than you bargined floor (sic).

[Soyboy]

Thanks Wabbiter.

I have looked over as much of the trailer as I can see and pull apart fairly easily including the front under the couch and have not (knock wood) found further rot. The bathroom floor of course is always a question. It has the original carpet and I am going to pull that up after camping season is over and take a look. The PO replaced the rest of the cart with cork (did a nice job) and said there was no rot in the areas that he was able to see (seemed like an honest guy).

[Wabbiteer]

The patch - use equivalent thickness plywood - lay reinforcing plates underneath the floor edges, say 4-inch-wide same-thickness plywood with 2-inches exposed to make a ledge to set patch section on, use plenty of fasteners but beware punching through into anything vital..

Slots in the piece? To loosen & retighten bolts you'll need access to top and bottom, inner liners off or lifted away and the wraps dropped to reach the other side. As long as thats going on its sturdier and longer lived to not slot anything but drill each hole as needed. I know it's a train wreck in progress to get that deep but there are no shortcuts I know about...

Coating the plywood especially the edges with sealants - poly. epoxy resin, etc. is where to go, no man-made wood current has the stiffness and resistance to heave and vibration that 5 or 7 layers of plywood laminations do.

[ROBERTSUNRUS]

Hi, I don't want to have a problem with my trailer's rear floor and I don't want to needlessly remove the lower body moulding to seal the body to frame area if not needed or by chance already done. Others who say this area is the problem also have leaking panaoramic windows and other's have a storage door that leaks. I don't have the wrap around windows and I don't have a rear storage door. If you have the twin beds, does that mean that you have three rear storage doors? One on each side and one in the rear, above the bumper? Could it be the doors leaked instead of the bumper area? It seems lately quite a few people have found floor rot in the rear of their trailers, mostly FB models with panaoramic windows in the back. And they seem to believe that the rear bumper area caused it. But I haven't read where some one was 100% sure the bumper area was the problem versus the windows and rear storage doors. On the other hand, I haven't heard of any Safari's with this concern until your post.

Soyboy, do you have an Excella or a Safari?

[Soyboy]

Robert, I have a Safari with the twin beds and no panoramic windows. From where the rot is/was, I don't think it was the door (although that was my first thought), the bad floor was tucked off to the curb side, most of it away from the door. There seems to be a little bit of rot starting right up against the wall (in the c channel?) next to wear most of the rotted floor was. After reading a number of other threads on here (which is what drve me to check out the trunk floor), I would be willing to bet it was leaking under the rub rail. That whole design is problematic and why Airstream let's it go on is beyond me! bob Wheeler was on The VAP podcast last week, I would love to have asked him about this, and why they don!t do a simple re-design to correct it. If I had a newer, just out of warranty unit, I would really be upset after I read about how long this problem had been going on! I didn't get too torqued about it as I was not surprised to find it. I am just glad that I found it before it spread across the floor. Right now it is a pain in the butt repair, but not a major repair. I do know that all off the carpet is coming out off the storage compartments this weekend! BTW, I do have the two side storage areas you asked about. Everyone with this design needs to keep a close eye on things and I would recommend pulling the carpet ASAP, as it can hide damage and trap moisture. There are lots of posts on here about this problem and it's fixes. I guess some folks are lucky and don't have problems with this, but too many do, and some may have it and not realize it until it's created major problems.

[Soyboy]

Robert, one other thought on your post, I think Airstream considers this upkeep to the rear of the trailer (removing the trim and caulking) owner maintenance. It seems crazy I know, but if you go back to them with leak issues, it seems from may posts they say they are caused by a lack of maintenance. However, to me popping off the trim, drill out the rivets that hold the rub rail on and then caulking seems to go beyond the realm of "maintenance".

Here are a couple of posts about the topic:

http://www.airforums.com/forums/f456...ybe-56674.html

http://www.airforums.com/forums/f456...per-32216.html

http://www.airforums.com/forums/f36/...lla-66738.html

http://www.airforums.com/forums/f36/...dea-59266.html

It happens to older trailers and newer ones. In particular it seems to happen to the trailers that have the hinged storage compartment in the rear bumper. The Alum piece that holds the hinge apparently runs back under the skin to where the floor is, if the seal leaks, then water is sent right back against the wood and it starts to rot. Of all of the leak problems that AS has, it seems that some simple engineering could correct this (some have proposed solutions on here).

BTW Robert, it would be interesting to get Airstream's "official" take on how to maintenance against having this problem. Again, it seems crazy that they expect folks to remove trim to check the seal. Even if they do recommend that, how often? I doubt that they have an answer.

[Soyboy]

Today I pulled the carpet from the rear trunk. Other than the rot that I found earlier, the rest of the floor was in good shape. I also pull the carpet from the curb side storage area. That way I can monitor the condition of the wood. On the street side there is a piece of alum. along the wall that protects some wires, but I can can still keep an eye on that area. After we get back from the beach next week, I will work on applying a CPES epoxy. I want to wait as I know that takes a few days to dry and I won't have time before we leave this week. I the area that is damaged is along the "curved" area of the rear so I will need to make a template in order to cut the piece to fit. Like Wabbiter suggested, I am going to add some support pieces under the existing plywood and screw it all together. Now I need to figure out how to pull the trim so I can caulk along the floor/skin seam to help to prevent this in the future. Tips for that are welcome!

[ROBERTSUNRUS]

Originally Posted by Soyboy

Now I need to figure out how to pull the trim so I can caulk along the floor/skin seam to help to prevent this in the future. Tips for that are welcome!

Hi, I think I will seal mine without removing the lower moulding. As you know, this moulding is sealed on the top edge all the way around and open on the bottom. The bottom of this moulding on my trailer fits pretty tight, on top of the hinge plate. My plan is to seal the bottom of this moulding where it sits on top of the hinge plate and fill the ends of it with sealer at each side by the top of the frame rails. This will block any water from entering in the area where the body meets hinge plate.

[Soyboy]

I thought about doing that too, but on other threads the point has been made that if water leaks in from another area, say a window, you will be sealing it in and causing more rot. Also, it makes if that was a good fix, why isn't Airstream doing that at the factory? I can only assume because it is not the right way to correct the problem. I am still planning on figuring out how to remove the trim, and caulking behind it, although I don't think AS does that either. It is really a weird design.