Aluminum Floor Corrosion

[Joe]

We have a 1998 2720SL. About a year ago we began to notice some bulges in the vinyl flooring in the kitchen area and the vinyl had discolored in that area. Then recently my wife wanted to replace the carpeting. So I pulled up the carpet and also the vinyl.The bulges under the vinyl are caused by the aluminum corroding. The aluminum is glued to luan plywood. There are several places around the refrigerator where the aluminum had corroded to the point that has been eaten away alltogether. The same thing occurs in front of the cabinet under the air conditioner. I've dug out most of the powder-like residue and cut away most of the weakened aluminum. The problem appears to be that water stood on the floor and seeped down between the aluminum and the luan. The galvanic action or whatever you call it, caused the aluminu to be eaten away.
I want to put new vinyl in the whole area. I contacted the factory and they suggested that I cover the entire floor with luan and then glue the vinyl to that. I'm concerned that the aluminum will continue to corrode and in a few years we'll have a similar or worse problem.
Right now I plan to coat the floor with a primer that is made for installing vinyl flooring, and then gluing the vinyl to that.
Does anyone have any suggestions or experience with this situation?

Joe, I can't quite visualize where along the floor your corrosion is occurring. Also, I've never taken up the carpet or vinyl on top of the floor of my TM. Is there a layer of Lauan plywood (Phillippine mahogany) on top of the aluminum sheet (the upper sheet of the 3" thick foam-aluminum sandwich of the floor)? I would guess that leaked water penetrated the vinyl/carpet and got to the Lauan plywood. With this layer then soaking up the water, the aluminum came into contact with the water. An electrical connection was formed by the water between the aluminum and a bare steel part of the refrigerator (or some other steel or copper part). This created a simple battery. Since aluminum is lower on the Electromotive Scale than iron and copper (steel contains iron), the aluminum was corroded in preference to the steel by the action of the battery. Your aluminum floor was corroded just like the zinc anode of the water heater is corroded. In the latter case it preserves the water heater's components. In the former case it's a destructive process.

You can solve the problem by creating a moisture barrier between the aluminum and steel. For example, consider running the new sheet vinyl under the refrigerator and forming its edges upward to create a pan at the rear and two sides of the refrigerator. That will funnel any leaked water to the front of the refrigerator where you can promptly mop it up. Of course, it will help to locate any source of a water leak from the refrigerator and seal it off. A plastic drain tube from the vinyl "pan" that will take water through the floor and deposit it below the TM may help also. Other helpful measures may include applying several coats of marine varnish to the Lauan sheet and applying a layer of pitch between Lauan and aluminum (messy work!). The outer layers of varnish will minimize the Lauan's ability to absorb and retain moisture. The pitch will act as an additional electrical barrier, or insulator, between the aluminum and steel.

As I'm not familiar with the layout of a 2720SL, all of my comments are just generalizations about ways to prevent corrosion of the aluminum floor. The specific details that may be required to carry out these recommendations will depend on the physical layout of the refrigerator and air conditioner in your 2720SL. You can fix it. It will just take a bit of work.

[Joe]

Larry,
I'm sorry for the late reply but when I didn't get a reply I went on and fixed the problem as best I could. (My wife had promised our daughter that we would go camping with them during their spring break.)
The lauan plywood is between the aluminum and the styrofoam. I was surprised to see it; I thought the aluminum was bonded directly to the styrofoam. The corrosion occurred where there were screws and staples. I had never noticed water standing on the floor but apparently it had, and seeped down the screw and staple holes so that the plywood got wet. The wet plywood reacted with the aluminum and the aluminum corroded. I'm familiar with that type of corrosion; we had an old occurred many years ago in which the 2 piece top folded out to make the bed. The top pieces were pressed board covered with aluminum. Over the years the aluminum developed a leak and water got into the pressed board. After a few years I noticed that the aluminum was corroding. There was someone on this forum who was having a similar problem with his door.
I fixed my problem by cutting away as much of the corroded aluminum as I could. There was one area that was about 12 X 6 inches. After getting as much of it up as I could, I followed the lead of someone else on this forum and went to Lowes and got some Armstrong patch, underlayment, and embossing leveler and mixed that with underlayment additive. I troweled this on the floor and let it set overnight. The next day I sanded down some high spots and mixed another batch to fill in some low spots. It dries hard almost like epoxy body filler. When I had achieved the smoothness I wanted, I made a paper template for the vinyl flooring. I cut the vinyl and checked it for fit. Then I spread the vinyl cement and installed the vinyl. It helped to remove all the cabinet doors so that I could get the vinyl positioned without too much bending.
I could go into more detail about how I did it but, it's probably enough to say that my wife is pleased with the results.

Joe

Congratulations, Joe. it sounds to me as if you used a satisfactory method of repairing your corroded aluminum floor panel and came up with a good cosmetic repair.

[Joesjunk]

I was thinking about replacing the green carpet in my 2000 2720 TM. I would like to know if there is vinyl under the carpet. Looking at different flooring products.

[Joe]

No, at least in ours. Under the carpet is the aluminum like that on the sidewalls. Where the carpet meets the vinyl it isis held down by the metal strips, just like it is done in houses. Where the carpet meets the cabinets, there is 1/4 round molding that we took up. Under that the carpet is stapled to the aluminum. We tore the carpet loose, and the foam pad under it, then we used a tack puller and pliers to remove the staples. Be careful with those metal strips, they have many barbs that will prick your fingers. Early on, we decided to not reuse the molding. It's wood covered with a paper-thin vinyl. We went to Lowes and bought a couple of strips of real wood molding, stained them to match the other wood and it looks great, at least we think so.

[Leslie & Nick]

Originally Posted by Joesjunk

I was thinking about replacing the green carpet in my 2000 2720 TM. I would like to know if there is vinyl under the carpet. Looking at different flooring products.

I removed the carpet (and vinyl) from my 2619 last year. As I recall there was no vinyl under the carpet. It was just stapled to the floor at the edges, with what seemed like a million tiny staples (there actually weren't a million, but it seemed that way ) I layed down a new maple laminate floor that has worked out well, and is a lot easier to keep clean.
Nick

I've been wondering about tearing out the carpet and vinyl and putting in peel and stick tiles. I wonder if they would stick well enough. I put them in a kitchen once and the worked real well - they're probably still there because the people we sold that house to haven't made any changes to it (in 18 years) as far as I can tell. It's still the same paint on the outside that I put on 20+ years ago!

I put peel and stick tiles down in the kitchen area. After the sheet vinyl comes up there is a residue of old glue over the aluminum floor. Mineral spirits seems to work best to get this up, but it seems as if the floor never really gets 100% clean as if it ends up with a residue which is slightly tacky to the touch. In any case, I learned the hard way that the peel and stick tiles do not stick very well to this cleaned floor. The floor aluminum is the same stuff as on the the walls and ceiling - a little shiny and a little dimpled - and the same stuff that velcro has trouble sticking to reliably.
The secret is to skim on a very, very thin coat of vinyl tile adhesive/primer as a primer (I got it at Lowes). The tiles then stick just great!

Paul

Thanks for the info. You saved me the "trial and error" process. I think I'll do that when the TM comes out of hibernation! Thanks!