Sealing Subfloor - Polyurethane vs Penetrating Epoxy

[rkgnaz]

Originally Posted by RareStream

Use marine plywood. Don't skimp on the wood. The best marine plywood is your BEST line of defense.

Only seal the floor with epoxy if you can be 100% absolutely sure that every single nook, crannie, hole, and edge are totally 100% completely and imperviously sealed.

If you leave one tiny, tint spot open to moisture entry, it will NOT be able to escape and the floor will rot from the inside out.

Don't ask how I found THAT out.

Epoxy is the best way to go.
After mixing it with the hardener, thin it about 50% and liberally brush it on. It’ll soak into the wood and make it impervious to moisture.

[ehodg66]

Originally Posted by rkgnaz

Epoxy is the best way to go.
After mixing it with the hardener, thin it about 50% and liberally brush it on. It’ll soak into the wood and make it impervious to moisture.

What type off thinner would your use?


thank you

[eksine]

Originally Posted by rkgnaz

Epoxy is the best way to go.
After mixing it with the hardener, thin it about 50% and liberally brush it on. It’ll soak into the wood and make it impervious to moisture.

Epoxy is one of the thickest coatings you can put on something. It does not soak into the wood. It lays on the top surface. The other user who said he used Thompson water sealer is a very smart. It is the next best thing to just buying marine grade plywood. Wood sealer is thinner and might have solvents or oils and waxes to help soak into the wood. If you seal it first than use epoxy that would be a strong combination

Another thing to consider is a non organic material. This eliminates rotting altogether. Honeycomb, High-Density Polyethylene HDPE might work (marine grade starboard or non marine puckboard), using steel sheeting, etc. Do research on man made materials that can withstand the loads plywood can handle. I remember a synthetic material advertise as a replacement for plywood once so I know something synthetic exists.

You could just glue thin metal sheeting to rigid foam board, the top will withstand wear, plus free insulation, use construction adhesive or something

[dznf0g]

Originally Posted by eksine

Epoxy is one of the thickest coatings you can put on something. It does not soak into the wood. It lays on the top surface. The other user who said he used Thompson water sealer is a very smart. It is the next best thing to just buying marine grade plywood. Wood sealer is thinner and might have solvents or oils and waxes to help soak into the wood. If you seal it first than use epoxy that would be a strong combination

Another thing to consider is a non organic material. This eliminates rotting altogether. Honeycomb, High-Density Polyethylene HDPE might work (marine grade starboard or non marine puckboard), using steel sheeting, etc. Do research on man made materials that can withstand the loads plywood can handle. I remember a synthetic material advertise as a replacement for plywood once so I know something synthetic exists.

You could just glue thin metal sheeting to rigid foam board, the top will withstand wear, plus free insulation, use construction adhesive or something

Perhaps you are not familiar with penetrating epoxy. It was developed primarily for the marine industry. It would be the only coating I would use and recommend for an AS floor. Perhaps followed up with a coat of medium body marine epoxy.

[eksine]

Originally Posted by dznf0g

Perhaps you are not familiar with penetrating epoxy. It was developed primarily for the marine industry. It would be the only coating I would use and recommend for an AS floor. Perhaps followed up with a coat of medium body marine epoxy.

no penetrating epoxy is falsely advertised. this guy tested it and it failed.

https://www.epoxyworks.com/index.php...y-legend-myth/

it's true I based my assumption on my experience spraying 2k polyurethane, but I've heard of epoxy used as a direct to metal on cars as the foundation. again it's too thick and has poor penetration as his demonstration shows how it fails to do so

[barts]

If one were doing a complete frame-off rebuild, replacing the entire floor with a rot-proof material is ideal... however, that's a very small percentage of cases. Most trailers have limited areas with rot, and local repairs with of course stopping the leaks are a cost-effective solution.

As I said several years ago, the wood floor in an Airstream has numerous penetrations, and it is not possible to completely waterproof the plywood. The goal is to forestall rot long enough so the owner can discover the source of the leak and deal with the problem w/o significant damage.


What we did was:

• Repair the floor by removing rotted sections of plywood, fitting butt-blocks to support edges, and gluing & screwing in new pieces.
• Coat floor with multiple coats of xylene-thinned epoxy. You can use penetrating epoxy if you wish; it's the same thing, perhaps w/ different solvents. Proper vigorous ventilation of the trailer is a must!
• Paint floor with moisture-cured polyurethane paint, which is very tough and has not shown significant wear in the 10+ years of use.

Are other solutions practical? Absolutely. A good quality floor & porch enamel would likely achieve the same thing. Remember, the goal is simple - prevent undetected rot from occurring. If you park the trailer in a field for 20 years and never look inside, problems can and will occur. If you use the trailer every year and look under the carpets and investigate any moisture signs, the floor will likely last indefinitely given any one of a number of options.

Wall-to-wall carpeting is not a good thing in a trailer. It's difficult to clean in-situ, and it hides water leaks and holds moisture next to the wood. We use rugs in our trailer, and remove them for cleaning - important, since our trailer generally gets used in muddy, sandy and dusty places, not paved RV parks.

- Bart

[eksine]

For cost effectiveness I agree. I'm not an Airstream owner, but don't most of you guy want to keep this trailer forever? If you stop using anything that can rot with something synthetic like I mentioned you would have access to the floor so you can cut off and replace any rusted metal and/or coat it with a rust to primer spray and coat all the metal so it wont rust as much. you could even replace the entire bottom with aluminum tube, thick enough to replace the original frame. if the carpets are getting dirty there must be air going through the floor no? maybe you can use metal sheeting or plastic to form a guard on the bottom like what cars have.