Floor Rotted Needs to be Replaced

[BriAnne81]

We bought a 92 Excella and our floor by bedroom is rotted and needs to be replaced. We have no idea what to use or how to do it. We were told Coosa Boards are best. Can’t find them in our area, Corpus the Christi Tx. Anyone have any ideas or recommendations on what to use or best way to do it?

[CliffSpace]

I have same model, same problem. I tried to get marine plywood, 5/8" thick but its not available to me. They told me that poplar with waterproof glue is good for exterior use so I am getting that.

[waninae39]

why not use the same non-wood product that AS uses in all the new trailers
see if you can get that as there would be no seams

[gamakai]

5/8" marine ply should be available in your area. Disassemble (take pics as you go so assembly is easier) as much furniture as you can so you an easy place to work. Remove bad material, including wood in the channel along the side. Cut and install new wood-making sure seams align frame and new wood is inserted in the side channel. It's not difficult-just labor

[richard5933]

Try and find a plywood dealer instead of looking in box stores. Most every city with a decent size should have at least one good plywood dealer which sells (or can get) every variety out there in all sizes.

[Bill M.]

Guess I am in the minority. I used something close to 5/8" exterior sheeting from the box store. I think that is fine for a sub floor. Same glue as the marine plywood but the plies are of poorer veneers and it may have gaps inside. The secret to making it last is to fix the leaks. I found the job both difficult physically and mentally somewhat difficult also. I ran into all kinds of things I was not expecting in the trailer tongue area. But...I am pleased with the results for the areas I did. I did dig all out of the old OSB out of the c channel and inserted pieces of plywood back into the c channel and then spliced them into the bigger sheets of flooring used blocking under the joints. I put a tongue and groove laminated flooring over the area and a carpet over that so I was not too concerned with getting perfect joints in the subfloor.

[Dingo Girl]

I used 5/8 ACX, purchased at a local lumber yard.
then coated it with penetrating epoxy. Several coats near the edge of the floor.
I also coated a scrap piece of plywood and put it outside under the eve of the shed. That was about 8 years ago. Its still in fine shape.
Hoping you find the materials you need��

[Bubba L]

Originally Posted by Dingo Girl

I used 5/8 ACX, purchased at a local lumber yard.
then coated it with penetrating epoxy. Several coats near the edge of the floor.
I also coated a scrap piece of plywood and put it outside under the eve of the shed. That was about 8 years ago. Its still in fine shape.
Hoping you find the materials you need��

We did a shell off on the 55 years ago. We used penetrating epoxy a couple of feet in from the edges on top and bottom from TotalBoat. We felt confident it would seal and protect. Also, keep your eyes on any leaks. Good luck

[AlbertF]

Originally Posted by waninae39

why not use the same non-wood product that AS uses in all the new trailers
see if you can get that as there would be no seams

That would require a shell-off restoration. Piecing in plywood and splicing it as described in this thread is how Airstream recommended it in the 1970s service manual I had with our old trailer.

[jerunamuck]

Just finishing up my 2nd round of floor repair on my 90 Excella.

I chose NOT to do a frame off replacement but to just patch the rotten parts. That makes things interesting.

1st. I use 3/4 marine OSB. This way it matches up with the 3/4 sub floor I'm not replacing. I chose the marine grade because it is designed for use in wet environments and resists rot. I chose OSB because delamination is less of an issue than with ply and is generally stronger than ply.

2nd. it takes some investigation (cutting out small sections) to cut up to the edge of the steel frame but not over it. Doing so leaves existing flooring securely screwed to the frame. This will leave you with no place to screw down the new floor sections.

To solve this I cut 2 inch angle iron to fit between the floor members and used 1/4 inch self tapping bolts to bolt the angle iron to the existing frame. Now I have a 2 inch surface to screw the new floor sections to. A small C clamp and level will hold the angle iron in place while drilling and screwing it to the frame.

Under floor insulation was the reason for the floor rotting in the back of the camper and a leaking ceiling vent was the reason for the rot in the front of the camper i just fixed. Ultimately, in both cases I had to pull several inside wall panels off to expose the leaks and slather copious amounts of Sikaflex 221 on the inside of the outer skin to seal some things. For example, someone replaced the front left lower outside panel but did not properly seal the seams so every time it rained water seaped in. A rubber glove and half a bottle of Sikaflex liberally applied to the inside surface of the outer skin makes sure that seam will not leak through. Same for an after market solar panel installed on the roof and bolted through the vent frame. (Idiots!). A set of Calico fasteners was the best investment I've made in years. Made replacing the inside wall panels a breeze.

Back to under floor insulation. I ripped out all the fiber grass batting I could find under the floor. After 50 years it was lying in the pan, getting wet and wicking moisture into the underside of the sub floor. I replaced it with 2 inch rigid foam blocks. They're water proof and you can glue small pieces on the bottom so they stand off the lower pan leaving an air gap. A little Good Stuff spray foam on top right before I put down the new sub floor panel glues them in place nicely.

Here is the hard part. The bottom of the walls is an aluminum U channel two inches wide facing up with a 1/2 inch C channel underneath facing in. When removing the rotten wood, you will likely need to dig the old wood out from that 1/2 inch C channel with a small wood chisel. There are wires and screws through it you will need to either unscrew or otherwise cut to get all the wood bits out. Some of these are 1/4 and 1/2 inch bolts, do not cut those. Most are wood screws you'll either need to unscrew or cut with a dremel to get out. Cleas as much as you can and mark or make a note of where you removed wood screws for later replacement.

Unless you're doing a full frame off restoration, you will need to make templates for several pieces of wood. The pattern that worked best for me was to make a template for the side/corner pieces and a separate one for the center/end piece. This allowed me to slip the corner under the U channel and pivot it in to the side. Once I had both corners/sides in place, I could put a large center piece in pushing it under the U channel at the end of the trailer.

For the templates I used corrugated plastic sheets. Easy to cut with a utility knife and relatively inexpensive.

After cutting the 3/4 inch OSB to match the template. I used a router to make a 1/4 x 2 inch rabbit around the outside edge. Now cut out notches as necessary for the 1/4 and 1/2 inch bolts holding the wall to the frame as well as any wires that go through. Finally, rough sand the outside bottom edge so you don't have problems trying to slip the wood into the C channel. This allows the wood to slip easily into the C channel under the U channel of the wall. Once it's in place screw it down to the frame and angle irons AND replace the wood screws you removed from the U channel.

With all the pieces in place, use wood filler in the gaps and rough sand all the edges away to prevent flooring from cracking. The back bedroom took me a month of weekends and some afternoons to do. The front has taken me almost two months of weekends and a few afternoons because I had to repair the gaucho and replace a bunch of wiring. Since I had the walls and ceiling exposed, I also took the opportunity to install a 5G cellular modem antenna on the roof and the modem under the gaucho.