Undercoating Alternative (No more sticky black stuff!)

[stman]

I actually used this stuff on my build, it sticks very well, ( note in the heat of summer it will get very soft) not a prob if you don,t touch it just messy as i used it on all corners where wall met floor or roof as well as around all the doors and windows. No water is going to get at the wood on my trailer, well worth the small cost. extra protection is a good thing. Like the rest of my trailer it's "Over built"

This stuff sounds like a really good Ideal....Does it cure so that it feels dry when you touch it?I used the paint on in a can on the first floor I built because everyone on here was using it.It never dryed or cured and the smell never went away.I threw that floor away and painted my new floor and covered it with a heavy piece of plactic.I am starting a new build and was looking for some Ideals. thanks

[kbuddy]

underneath my floor is 6.6 x 12 so the asphalt tape was pretty expensive.. i put a coat of rustoleum truck bed lining.. but it was also expensive and didnt coat very thick.. so i put a layer of the asphalt roof emulsion on top.. which is messy and everything..

anyway.. the point of my post... after i got done with all of that, i thought.. why didnt i just put linoleum under there? easy to apply, super durable.. water proof.. not very expensive.. anyway i haven't tried it.. but just a thought

[bobnlyd]

why not just a 24ga galvanized sheet...seems most rigs are 4X10...and its under 20bucks a sheet...cheaper alt is galvalume or zincalume

[jimqpublic]

After replacing some rotted OSB on the floor of my A-frame trailer last year- and finding more this year...

I think completely waterproofing both the bottom and top of the floor is a recipe for disaster. Any water that gets in can't get out. I live in southern California- we get more dew than rain. Unfortunately a tiny bit of dew dripping down every day was wicking around a molding and seeping into the edge of the flooring. Vinyl on top, poly sheeting on the bottom- No where for the moisture to get out.

I suggest latex paint to coat the bottom. Very water resistant, but vapor semi-permeable allowing it to dry out over time.

Also watch out for that bottom trim molding!

[markhusbands]

After replacing some rotted OSB on the floor of my A-frame trailer last year- and finding more this year...

I think completely waterproofing both the bottom and top of the floor is a recipe for disaster. Any water that gets in can't get out. I live in southern California- we get more dew than rain. Unfortunately a tiny bit of dew dripping down every day was wicking around a molding and seeping into the edge of the flooring. Vinyl on top, poly sheeting on the bottom- No where for the moisture to get out.

I suggest latex paint to coat the bottom. Very water resistant, but vapor semi-permeable allowing it to dry out over time.

Also watch out for that bottom trim molding!

So you'd just do a coat of something like Kilz and then the some exterior grade latex?

[markhusbands]

What about truck bed liner?

[linuxmanxxx]

This is a topic that most don't understand that waterproofing the bottom isn't near as important as making sure the roof and outside are sealed on the upper portions. It's highly unlikely anyone would experience floor rot from the minimal amount of water exposure from road spray while driving in the rain. So with that in mind a basic quick seal and water resisting underneath are acceptable. Where you need to make sure are the roof laps seams and corners are completely sealed with no leaking at all. All floor damage is usually from leaking up high and running down and saturating the floor area and then failure over time due to repeated wetting or not drying fast enough.

Easiest way to seal the outside is minimal seams and SKIN it. If you put an outer coating of aluminum, frp, filon, or even formica they are all naturally waterproof and then if you adhere them with a waterproof glue you further enhance the waterproof sealing. Then you only have to concentrate on corners, openings, and seams for sealing instead of if you do a wood exterior which you then have to completely sealing everything.

Back to the floor underneath....if you seal the complete outside the bottom is only going to encounter road spray traveling so a good hit with the 25/75 poly/mineral spirits of 3 or 4 coats and then a simple painting with exterior enamel would work just fine and much easier to deal with and handle than the roof coating nasty mess. Or do the mixture and then glue plasticore over it and bolt it down would be very nice clean looking and wouldn't ever have underneath failures either.

I know its pretty and draws attention but there's a reason why car manufacturers and the rv manufacturers don't put wood on the outside of what they build......it rots and leaks too easy.

[Photoman33770]

There is a group of people that build " Tiny Homes". The thing that is big with then is not so much to water proof the bottom but critter proof it. They use aluminum flashing and run how ever many strips they need with a small over lap. Other way would be to use the stuff I used on my porch roof which comes in wider rolls called peel and seal. It has a paper peel off and a VERY sticky rubber like base ( stuck down it is not coming up ) and has an aluminum skin. That would work even after a trailer is built as you can cut it and apply it in sections. Plan B would be like canoe builders and resin seal the sheets of ply on both surfaces and the edges to seal it totally so any water that got to the sheet would just set till cleaned up.

I hope over kill is not a bad thing!

[markhusbands]

I think given that I live in a dry place, and I don't like sticky stuff or stinky stuff, I'm just going with multiple coats of exterior house paint. I may also caulk around the frame to keep moisture from getting trapped between frame and floor. But I really think that road spray will dry pretty effectively here in Colorado in the summer. Am I crazy?

[bearfromobx]

You probably are crazy Mark, but that just makes you fit in 'round here so much better...

On my end of the world, salt and sand are as big a threat as water to the floor; I'll go with something like the truck bed liner, thanks.

Bear

[duckman903]

There is an other product called vitrothane (ice barrier) comes in a roll 36" wide just be right when putting down. I'm just a newbie but have used this product.

[Todah Tear]

I used coroplas (signboard)
Worked great...]

How is the coroplast holding up as an undercoating alternative? I have thought seriously about using it in that application as well.

Todah

[Martiangod]

The sign board works great, road dirts does not stick, waterproof, air space above so keeps dry, and can dry out if moisture were to get into the insulation cavity, almost all rv manufacturers use it for belly pan

[KauaiSean]

I used a waterproofing product called Red-Gard and waterproofed the outside of the teardrop to keep the thing from rotting away again. I bought a 4k Little Guy and it was rotten all long the bottom and lower sides of the camper. I have rebuilt the teardrop form scratch so to speak and reused the siding and I am hoping for the best. I think my overkill solution to moisture is do to the fact I normally live in the wettest place on earth, Kauai the smallest of the 4 major islands. We shall see what happens over time.

I got a shipping quote to Kauai from Oakland and cannot justify the expense of shipping the teardrop to Kauai so I will need to sell it before going back home.

[NathanL]

After replacing some rotted OSB on the floor of my A-frame trailer last year- and finding more this year...

I think completely waterproofing both the bottom and top of the floor is a recipe for disaster. Any water that gets in can't get out. I live in southern California- we get more dew than rain. Unfortunately a tiny bit of dew dripping down every day was wicking around a molding and seeping into the edge of the flooring. Vinyl on top, poly sheeting on the bottom- No where for the moisture to get out.

I suggest latex paint to coat the bottom. Very water resistant, but vapor semi-permeable allowing it to dry out over time.

Also watch out for that bottom trim molding!

I would say OSB lead to more of your problem than lack of good undercoating on the bottom.

You really need exterior grade plywood on the bottom, and not the "Exposure 1" stuff that most big box store sells but rather a plywood that is actually marked "Exterior" on the APA stamp rather than exposure 1 which is what you often get at Lowes/Home Depot that they put a sign over that says exterior plywood.

I didn't find the fibered roof asphalt all that big of a gooey mess. I poured it out on the plywood in a big lump, took a big board and spread it around while wearing a pair of throw away nitrile gloves. In our heat with it sitting out in the sun I could pick it up and move it without any getting on me with no gloves in about 4 hours. Flipped it over on the trailer and moved on.