Undercoating Alternative (No more sticky black stuff!)

[Rhino Ray]

I'm not planning to keep it parked outside, it should last for at lest the rest of my lifetime.

 

[skline25]

Another alternative is to use Herculiner, It is a DIY bed liner in a can. You can roll it on and once it dries it is real tough and holds up to the elements real well. We used it at work to cover a plywood platform that we used to hold heavy pelican cases and tough maid totes, pulling them in and out all day long. About 2 years ago, we bought a new truck with a roller bed system and the old plywood platform has been sitting out in the yard and still looks good, 3-6 feet of snow in the winter and 90 degree days in the summer and a bunch of rain in-between (Oregon).

 

[Constrictor]

I have a 6x12 box trailer that came with 3\4" chip board floor and ive hauled it coast to coast for 8 years.
I was up under it last summer to bolt some tie downs for motorcycles and i was surprised to find bare unpainted chip board in perfect shape! Is it possible a simple paint job would be actually better than undercoating? Perhaps letting it breath better?

 

[cuyeda]

yup, it is very similar to some actual car audio sound deadener I have. The sound deadener is supposed to be butyl rubber or something whereas this is asphalt, but the effect is the same. Black sticky stuff on a roll.
I will note that there were a few times that I wanted to adjust it slightly after laying it down and that wasn't happening... it was definitely stuck. The only way to move it would have destroyed it.

Sound deadener for the car! Marvelous! Can anyone tell us if this product gives off any asphalt odor. I wonder if it heats up a little with car mufflers under a floor pan if the product would be prone to an asphalt smell? I have a 65 Mustang 2+2 project, but that real stuff cost quite a bit more. Don't want to hijack the thread, just a quick comment.

 

[Tommy2bits]

yup, it is very similar to some actual car audio sound deadener I have. The sound deadener is supposed to be butyl rubber or something whereas this is asphalt, but the effect is the same. Black sticky stuff on a roll.
I will note that there were a few times that I wanted to adjust it slightly after laying it down and that wasn't happening... it was definitely stuck. The only way to move it would have destroyed it.

Sound deadener for the car! Marvelous! Can anyone tell us if this product gives off any asphalt odor. I wonder if it heats up a little with car mufflers under a floor pan if the product would be prone to an asphalt smell? I have a 65 Mustang 2+2 project, but that real stuff cost quite a bit more. Don't want to hijack the thread, just a quick comment.

I never noticed any odor when using it on my truck or my Monte Carlo. I used the generic stuff from home depot for my mobile home and it smelled fine too. Looks to be made of different stuff.

 

[Gadget Man-TNT]

I'm glad I found this post.
I've been living in the "Cargo Trailer Conversion" section for the past 8 months. check out Gadget Mans Adventure Trailer.
I'm doing a 7x14 cargo trailer conversion and the floor is one of my next projects, right now the bottom is bare 3/4 inch dense chip press board.
The problem is, that what ever I do will have to be applied from the bottom up, since the trailer is already built.
I thought of some type of spray or roll on "black Stuff" ...??? yuck.
But I like Martaingod's idea of using the plastic sign board cardboard and screwing it to the bottom frame, but I'm sure it's pretty expensive for over 100 sq feet.

But I also liked Constrictor's story about how after 8 years, he see's no excessive wear to the underside of his wooden floor. ?. I've always wondered.???
Right now, I think I'll just paint the wood with some quality house paint. I'm sure I have a gallon or two laying around. who cares what color it is....

Gadget Man

 

[Tommy2bits]

I agree with the house paint concept to a point. Your house will get hit with 60 MPH rain but the trailer will be traveling at 60 MPH and getting hit with rocks. Just a thought, not trying to start a argument

 

[PcHistorian]

This is IT!!! I found you guys!!! Right topic. Ok, Trailer is built, came with particle (chip compressed) floor and nothing I could tell on the bottom. About 5/8" from the looks of it. I guess it was made in the 1980's. (I will get some under pictures up here today, if I can...) I have put on one layer of thompson's deck water seal, last year. (this was before I found you guys). Now this last winter it got cold and I threw some piece of 1/2 blue insulation on the floor and man that was a great help. But NOW I want to put that insulation, attached, underneath. So I want a good sealing of the wood, then stick up the insulation, probably short deck screws with disks to attach. I am going to do some other stuff under there like water tanks of PVC TUBES. But those I'll attach to the frame. What's a good way to seal and then stick the insul. up, just prior to the screws? At 5/8" I think it will be tight to screw for hold and not come through with the tip of the screw.... (that's be an owie) I do plan to lay carpet inside, after I'm done doing the work. while I'm doing the work to finish it, I'd hate to get stuck with screw tips. So maybe 1" screws and the disk will help for the final spacing? I had been considering just the spray can tar stuff to undercoat... (plus I need to go back through here and take notes...

foam to transfer

current under

tanks to add
design

locations

I've gone through the thompsons water seal with paint brush underneath and some oil stain inside under the roof and I'm pretty much done with getting dripped on.

 

[Scouterjan]

foam board adhesive should work fine, its 1 of the PL\s in a calking tube, it won't melt the foam then a tar emulsion to seal it up, especially where the foam joins the frame, you don't want to trap any water in there
Jan

 

[PcHistorian]

Gadget Man, home depot does have a black spray stuff for sealing leaks in things, like seals up a colander. I am thinking about using that, depending upon how long it takes to dry, to seal up my floor as well as stick on the insulation. I still have to think about more cross braces underneath. Anyone here have trouble with 2' x 4' spans in the under frame for 5/8" chip board? (I do tend to load up rather heavy at times... stumps for cutting up for fire wood, etc... )

 

[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-TNT]

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-TNT]

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-TNT]

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-TNT]

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