Waterproof exterior (but still lightweight)

[tcolar]

Because rain/mold is an ever present issue here in the PNW (even in the home), I'd like to know what work best for the outside of the trailer as far as waterproofing goes ?

- Using an oil stain on the wood exterior(deck stain) ?
- Fiberglass (maybe with an extra waterproof coating on top) - BTW, is fiberglass very waterproof (I would guess yes, since used in boats)

and so on ...

Anybody got leak problems and tips on what NOT TO DO to avoid them.

Thanks.

[Ageless]

Must I repeat myself?

Sealing the outside will not stop wood rot on the inside. Here on the West Coast moisture will get to the wood inside. Seal everything!

As far as the exterior; from most builds; it's either epoxy or aluminum. And then even the wood is sealed under the aluminum. The other options that have been used; filon, FRP, vinyl, etc; still seal the wood prior to covering.

[tcolar]

So I guess, seal ALL wood with an oil based wood stain and use stained/painted epoxy on the outside.

Does that sound good ?

[planovet]

Must I repeat myself?

He's a newb, give him a break

Seal EVERYTHING. Every side, every edge. Epoxy/glass is best, CPES is next. Deck sealants don't last long.

And yes, I would seal before covering. Just my $.02.

[tcolar]

Thanks, sound good

Thanks for taking the time to repeat

Sorry for asking questions that where previously answered, I realize most questions are already answered ... but there is so much infos it can be hard to dig out, even though I've already spent countless hours on this site (and learned a ton)

[doug hodder]

I would NOT use an OIL based stain under any epoxy. The oil will not allow the epoxy to bond well. An aniline dye would be a better choice, it's either a water or alcohol based item, water is better for UV longevity. Maybe Miriam has the link to the tests on epoxy over oil. Once epoxied...you need to top coat the epoxy with a UV resistant finish. Doug

[tcolar]

Yeah that makes sense, I was thinking the same thing.

A water barrier under the epoxy sounds like it could/would prevent proper bonding.

[mikeschn]

I would consider sealing everything in at least 2 coats of watco danish oil.

I've not tried putting anything on top of that... maybe a small test is in order?

Mike...

[michaelwpayton]

1st - start with GOOD plywood... the best (as far as moisture and rot resistance) that you can afford. There is a lot of junk out there at the BORG and blue BORG. You can research the various "grades" of, and "standards" relating to, plywood... but, BS1088 is the best, then BS6566, then all others.

2nd - ALL of that GOOD wood MUST be sealed. I think epoxy is the best way to do that. A number of people around here like "CPES," which is an epoxy-based product that you can research... but, there are many others.

3rd - Once you seal ALL your GOOD wood with epoxy... you MUST UV protect the epoxy. Epoxy is not UV resistant... UV protect it or you are wasting your time and money re the epoxy... and in turn your GOOD wood. You UV protect with paint or spar varnish (if you want a woody finish.)

[Shadow Catcher]

Or, do not use wood. What ain't wood can't rot, and what ain't steel cant rust.

[tcolar]

@michaelwpayton : Thanks for the detailed infos.

I have used danish oil before, pretty good, also that CPES looks like it's even better.

@ShadowCaster: no wood ? sounds interesting but not sure how that would work, is that the FB over foam method , can you explain ?

Thanks.

[aggie79]

I used both CPES and epoxy. It was my first time to use either product.

CPES does penetrate deeper than epoxy. However, CPES is primarily solvents so it takes longer to build a complete waterproof membrane.

I used both on the road side of my floor. First two coats of CPES, then one coat of epoxy. The reason for this was not intentional. I used all of the CPES I ordered, and because there was not a solid coat, I decided to switch to epoxy.

For the roof and sidewalls, I used one coat of epoxy. The one coat of epoxy appeared solid and I couldn't see any pores in the plywood as I could with two coats of CPES. I only used one coat because my teardrop has aluminum exterior.

[Steve_Cox]

CPES = a lot of volatile solvent and a little epoxy. Developed for rotten wood, not plywood, to turn it into a solid hard mass. I've used it and I've used a lot of epoxy.

I favor the epoxy, two coats on plywood flat surfaces, and 3 or more on plywood end grain or until the end grain surface is full and smooth with epoxy.

My experience with the CPES, with multiple coats on new plywood, the epoxy in the CPES mostly just left a thin coating on the surface, only thing that really penetrated the layers of wood was the solvents. I had a small scratch on the edge of the gypsy trailer roof that went through the EDPM roof coating. That edge of the plywood on the roof had at least 5 coats of CPES. In less than 2 weeks after a rainy night I had the start of delamination where the scratch was. It has since been repaired with...what else? Epoxy.. Hope my limited experience helps.

[teardrop_focus]

If I may add to the CPES topic, the inventor of CPES thinks that CPES is a great primer for varnish... and varnish is UV resistant.

[TD Beej]

I've been pondering how to make a TD water tight for a while, the basic plan that I've been leaning towards is to fiberglass and epoxy the heck out (all sides, edges and holes) of plywood and then skinning the exterior in aluminum (protection in layers). And though I've been vacillating on this, not insulating.

Reading this thread my latest brainwave is to use a hydrophobic blanket under the aluminum so even if a weakness is found in the aluminum shell the water would quickly drain out and it would also add a smidge of insulation, and the aluminum would then be able to act as a radiant barrier. Anyone have any thoughts, or a suggestion of a good hydrophobic material (fleece?).

Thanks, Beej