rear floor repair; having difficulty removing endcap curved interior skins

[Bob Blarney]

Hello, repairing the rear floor seems to be a rite/ordeal of passage for owners.

On the '95 Excella 30' rear bedroom:

The nasty carpet and pad are gone, and the mouse fur around the endcap is peeled off, but not off the side walls past the riveting strips (under the white plastic strips in the pic). I've removed the lower interior aluminum skin around the hatch.

But I'm having trouble removing the curved aluminum skins of the corners. I think I've drilled out all of the curved skin's rivets. Are there any rivets behind the overlapping upper & side skins? How much overlap is there with the upper skins? And how far do the corner skins run along the side walls?

Also, looking at the hatch door and its hinge plate. Is that the infamous plate that funnels water in? If it is, I'm inclined to remove it, and figure out some other way to support the hatch door, such as hinging it from the top edge with liftoff hinges and some kind of latch on the bottom edge for tight closure. Hmm, and that hatch might be an easier escape path than the window above it.

[perryg114]

Water usually gets under the floor from a plate that goes under the back of the trailer. The plate is the attach point for the bumper compartment door which yours may or may not have. The floor does not look that bad. I don't know why the skins won't come off. Chances are you missed some rivets hidden under the mouse fur. Mine does not have the mouse fur over the skins.

Perry

[A W Warn]

If there is a sliding drawer that pulls out of the rear bumper, you do not have the water through the wall problem. (fiberglass/rubber bumper cover)

If there is a fixed storage box between the frame rails that has a hinged lid, you do have water through the wall problem. (metal hinged lid)

add edit:
Looks like a spot in the center of the floor that has been wet. I would look at the fan closely.

[Bob Blarney]

Originally Posted by perryg114

Water usually gets under the floor from a plate that goes under the back of the trailer. The plate is the attach point for the bumper compartment door which yours may or may not have. The floor does not look that bad. I don't know why the skins won't come off. Chances are you missed some rivets hidden under the mouse fur. Mine does not have the mouse fur over the skins.

Perry

Perry, thanks. I've read through some of your past threads & other posts, and they've been helpfully informative.

I'll try slipping a thin stiff putty knife beneath the skin edges to see if I've missed hidden rivets (maybe I can chop them off too), and if necessary I'll peel off more of the mouse fur - it may not be such a loss. The floor is definitely rotted along the back wall, and there's a punky spot or two elsewhere too. I'm going to cut back at least to the seam, using a flooring blade to cut through the corrugated nails if needed. Coosa board seems to be the material of choice, if the budget can bear it. Marine ply has no advantages over ACX ply that I can think of, other than it's guaranteed void-free. If I use plywood, I'll fit and drill the holes, and then I'll remove it and epoxy the edges & holes, and also several inches in from the edge, and then fit it in again and fix it permanently in place.

One wonders why AS did not put an aluminum Z-strip around the perimeter between the channel and floor to protect the plywood. The outer skin could go over it, and the inner skin slipped in behind it, so that water would be directed outward. (I did this on my homebuilt flyweight tiny trailer, between its deck & walls made of XPS foam framed with red cedar) This could be done today at the AS factory today, with relatively little changes in assembly and cost.) Hmm, could that be done as part of the repair, by slipping aluminum coil stock in under the channel, and then beating the edges down on the outside and up on the inside?

About the bumper drawer (it's not a door), I haven't fully explored removing it yet. I don't recall that water pools in it, although the grey mouse fur seems a bit damp after a rain (I'll do a paper towel/kleenex test for wetness). I haven't found a release tab for the drawer slides, and I see they are riveted. So when I have a friend to help, I'll drill and pull it out and peek inside. Then I think I'll have a better understanding of the skeletal anatomy.

Looking at the rear bumper, it appears that the PO pranged it once while backing up, because it seems to slant inboard a tiny bit - enough to pool water next to the rubrail strip. That might be the origin and major cause of the rot problem.

[perryg114]

The seam under the rub rail and the plate is the source of many leaks. I got rid of the horizontal plate and therefore the need for perfect caulking. If the PO tweaked the rear end it probably helped the demise of the caulk seal at the back. When you get the skins off, look at awning brackets, tail lights, and leaks at window frame seams. Sewer pipe vents can leak and water pools at the back.

Perry

[Bob Blarney]

Originally Posted by perryg114

The seam under the rub rail and the plate is the source of many leaks. I got rid of the horizontal plate and therefore the need for perfect caulking. If the PO tweaked the rear end it probably helped the demise of the caulk seal at the back. When you get the skins off, look at awning brackets, tail lights, and leaks at window frame seams. Sewer pipe vents can leak and water pools at the back.

Perry

Arrgh! the teardown is expanding! Management will be disappointed.

I did find some rivets several inches under the overlapped side skin, and chopped them off with a heavy duty DeWalt demolition chisel (much faster than drilling, btw!).

But the corner skins are still stuck. Since I had planned to make twins that ride on slides to make a queen, I'd carefully amputated the rear side cabinets at the window line. But I think there are some hidden above where I cut the cabinets. Soooo, I guess the side cabinets must come out, and that means the center overhead cabinet must come out too. (Bob looks down despondently for a moment, but gets over it.)

I have already done an exterior resealing around all fittings and the roof, but it is a good idea to look again from the inside for specific trouble spots, and maybe make the tailights more easily removable.

[A W Warn]

Originally Posted by Bob Blarney

<<snip>>
Looking at the rear bumper, it appears that the PO pranged it once while backing up, because it seems to slant inboard a tiny bit - enough to pool water next to the rubrail strip. That might be the origin and major cause of the rot problem.

If the bumper cover is not broken, water should not be able to get to the wood floor. The bumper cover has a lip/flange that turns upward behind the aluminum/rub rail.

On my Excella the bumper cap also slants so that water flows toward the rub rail. Water does drip into the storage drawer at the edges joints, enough to rust out the bottom of the drawer on my trailer. If there is a plastic sheet in your drawer tray, remove it. It holds water beneath which accelerates the rusting process.

[4mer Paddler]

Originally Posted by A W Warn

If there is a sliding drawer that pulls out of the rear bumper, you do not have the water through the wall problem. (fiberglass/rubber bumper cover)

If there is a fixed storage box between the frame rails that has a hinged lid, you do have water through the wall problem. (metal hinged lid.

Just for my information, mine has the fixed box between the frame rails with hinged lid. However, the rear storage compartment has been replaced with an Onan 4000 genny sandwiched between rear twins. I’ve not noticed any water intrusion but maybe I’m not looking at it hard enough. Any pointers would be appreciated.

[bradt]

I started out with plans to just replace 3 feet of the rear floor. As work progressed, I kept finding things that I just couldn't leave "un-fixed". Management started questioning how much time I was spending out there, too.

I found my main leak was the hinged cover on the bumper storage compartment. But as I learned the what slow leaks looked like, I kept finding more.

The belly band area is an area of struggle. Many layers and levels coming together. The aluminum extrusion looks like it would protect the plywood. But when all is done, there are so many rivets, screws, and bolts that go thru the aluminum extrusion and penetrate the plywood, there is no practical way to pre-seal the plywood to keep it dry. And I think coatings to seal the plywood will help trap moisture. For example the belly band goes back on last, and has screws that go right from the outside into the edge of the plywood. Coosa board started looking better and better.

The general theme I developed was that the way the Airstream is made, there will always be multiple, small, low speed leaks from wicking, seepage, and capillary action. These leaks dont show up on the bubble test, and there are no puddles that you see when inspecting. So i started asking, how can this dry if it does get wet?

I looked at the rest of my plywood floor, and it had vinyl flooring sealing it from the top, and bubble foil on the bottom. And an area of carpet in the front bedroom. So i removed the bubble foil so the plywood could breathe from the bottom. Under the queen bed, there was clear plastic over the carpet, I guess to keep it clean during assembly at the factory. I cut the plastic away, and the carpet was damp! It was trapping water. I had been running a dehumidifier inside for a couple of months. Vapor seals definitely protect trapped moisture. I decided, since it is just storage, to cut away and remove the carpet under the bed, exposing bare plywood that can breathe and dry.

The carpet was stapled down along the aluminum walls around the bed. I removed the staples, pulled up the carpet edges, and could see staining from various small leaks. Fortunately, no rot. The carpet flops back down and stays in place without the staples because the bed sits on top. And I just plan to leave it that way.

Any place I exposed bare plywood, I sprayed it with Timbor to stop and prevent rot. Any wood sprayed w Timbor will not rot. It is great stuff.

Checked my marker lights and found that 9 of 11 leaked. The screws that pierce the outer skin were stained and the ones w bad plating had rusted. Some leaked a little, some a lot. I replaced them all, and the new ones were exactly the same and would also leak. So i modified them, adding neoprene gaskets and Trempro 635 in a few places, and finally drilled a small hole in the lens to allow it to breathe. They were all moisture collecting traps with holes thru the skin to the inside.

When you open up everything to replace the floor, there is a lot of opportunity to fix other things to prevent more rot in the future. Take some time to look around. But, it can cause a little trouble w managment sometimes...

[Bob Blarney]

Originally Posted by A W Warn

If there is a sliding drawer that pulls out of the rear bumper, you do not have the water through the wall problem. (fiberglass/rubber bumper cover)

If there is a fixed storage box between the frame rails that has a hinged lid, you do have water through the wall problem. (metal hinged lid)

add edit:
Looks like a spot in the center of the floor that has been wet. I would look at the fan closely.

Thanks for the reply.

Yes, the drawer pulls out on slides. The rubber bumper cover was cracked, and was sealed with Lexel. The bumper does slant slightly toward the rubrail, and the rubrail has been caulked now (the bumper cover design is stupid.). The wood inside the hatch is so wet, that I can't tell if everything overall is sealed until I get all of the wood cut out.


And yes, the fan flange was cracked on one corner and was leaking, although since the double bed was there and undamaged, I don't know how it could have caused that spot. it's been sealed.

[Bob Blarney]

Some progress has been made. I found a couple of rivets hidden beneath overlapping panels on one side, and sheared them off with a chisel to release the panel. But the roadside panel where the power lines run is not coming free. I fear there are still rivets under the curved upper panel that I can't reach because of the flexure of the panels.

1. Should I consider cutting the lower panel about 6-12" above the floor to access the channel?

2. If I did, what would be the best way to repair it? Rejoin the cutaway strip to the remaining upper part with a 3"-4" backer 'ribbon' strip to bridge the seam and rivet it?

[polarlyse]

Several years ago we had repairs to our '01 Excella. The repair involved replacing 2 curved panels ( 1 upper/ 1 lower on one side ) and 1 upper on the other side at the rear. I was told that the lower panels were difficult to remove and that they advised to overlay a new panel on top of the old making it double thick. The uppers are R&R and single thickness. He told me that there is structural pieces attached to the lowers and to remove them would require removal of the trailer interior. Now, I'm not sure if this is why you are having difficulty I'm just mentioning it since it may explain it. Of course if you have removed the interior panels and have a visual you would have seen this already.

I also found some dampness at the extreme rear inside my storage hatch that I'm keeping an eye on. So so much as to need replacement but perhaps an early warning in my case. That darned carpeting is sure a nuisance.

[Bob Blarney]

Originally Posted by polarlyse

Several years ago we had repairs to our '01 Excella. The repair involved replacing 2 curved panels ( 1 upper/ 1 lower on one side ) and 1 upper on the other side at the rear. I was told that the lower panels were difficult to remove and that they advised to overlay a new panel on top of the old making it double thick. The uppers are R&R and single thickness. He told me that there is structural pieces attached to the lowers and to remove them would require removal of the trailer interior. Now, I'm not sure if this is why you are having difficulty I'm just mentioning it since it may explain it. Of course if you have removed the interior panels and have a visual you would have seen this already.

I also found some dampness at the extreme rear inside my storage hatch that I'm keeping an eye on. So so much as to need replacement but perhaps an early warning in my case. That darned carpeting is sure a nuisance.

Thanks for the input. I hadn't considered just adding a second layer.

As for that carpet, I recommend that you remove it immediately, and replace with something easily removed for inspection and drying out.

[Bob Blarney]

Since I'm not in a hurry, I waited for suggestions and thought about how to remove the last panel, and this is what I'll try.

1. Re-rivet the top margin of the right corner panel back into place.

2. Acquire a 1/16" thick x 1-1/2" wide x 48" length strip of aluminum, and bend it to follow the shape of the panel at about 12" off the floor.

3. Hold the aluminum strip in place at 12" off the floor, and scribe a cut-line on the aluminum skin panel with a Sharpie.

4. Cut on the Sharpie line and remove the bottom 12" of the corner skin panel.

5. Slip the aluminum strip behind the remaining upper part of the skin panel and rivet them together to maintain the curvature.

6. Do the necessary work on subfloor.

7. Align the cut-away part of the skin panel on to the aluminum backer strip and the upper skin panel, and then rivet it in place. The backer strip will keep the upper and lower panels together without uneven kinks or buckling.

8. Replace mouse-fur wall covering.

By cutting the panel at 12" off the floor, I'll have enough room to work on the subfloor attachments, and also the seam of the rejoined panels will be hidden below the line of the bedframe and cabinets.

Any comments/advice?

[glrtex]

Having just done a complete gut job of my ‘76 Sovereign, I can tell you that the overlap is not consistent. It averages about 4”. If you cut where you plan to, you will never have sufficient overlap. How important is that? I will leave it to others...

Is it your intention just to do a quick fix on the problem floor area? How do you plan on cutting the lower panel? You need to be careful not to cut the ribs or wires that might be in the wall. There are quite a few in the street-side rear area.

[bradt]

This may not be for everyone, but i dropped the belly pan enough to locate the bolts from underneath and marked them top side. Then i cut a 2" hole with a new sharp holesaw thru the aluminum inner skin at each bolt location. This allowed me to access and remove bolts at the same time as i chipped away the rotten plywood. After complete, I inserted 2" plastic snap-in hole plugs. This way, I did not need to remove any of the interior skin, and the hole plugs look tidy and are mostly hidden by furniture. A compromise, but worked well for me.
Brad

[cliffcharb]

Brads idea is ideal if the interior skin is exposed. If it's hidden by furniture I'd cut a strip along the bottom as you suggested. These things get put in from the bottom up so it's difficult to locate all of the rivets as you've found out. The only issue with cutting small holes would be to find the hidden screws that seem to be installed also. I think they were used to hold the shell steady before it was bolted to the frame

[Bob Blarney]

Originally Posted by glrtex

Having just done a complete gut job of my ‘76 Sovereign, I can tell you that the overlap is not consistent. It averages about 4”. If you cut where you plan to, you will never have sufficient overlap. How important is that? I will leave it to others...

Is it your intention just to do a quick fix on the problem floor area? How do you plan on cutting the lower panel? You need to be careful not to cut the ribs or wires that might be in the wall. There are quite a few in the street-side rear area.

I'm not sure that you understood what I meant.

The lower panel would be cut horizontally about 12" off the floor, making two pieces with the upper piece still attached to the trailer wall by its top edge, and the lower piece would be removed to gain access.

After the floor was done, then the aluminum strip would be riveted to the cut edge of the upper piece (on the back insulation side) leaving ~3/4" margin. Next comes the replacement of piece that had been cut away to provide exposure.

The cut edge of the lower piece would be butted (not overlapped) against the cut edge of the upper piece and then riveted to the 3/4" margin of the aluminum strip. Thus the aluminum strip would act as a reinforcement batten to keep the cut edges aligned.

As far as the wires go, the lower part of the panel is free and can be pulled away from ribs and insulation so that I can see and avoid the wiring. Furthermore, in 1994, AS moved most of the wiring so it runs along on the floor on the left side, near but not inside the wall.