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Undercoating

PostPosted: Sun Oct 08, 2017 8:02 am
by randY49
Hi all,
I'm about to start construction on my teardrop and was planning to use Henry Asphalt Emulsion as my waterproofer for the underside of my floor (had read several builds that used this product). However, now that it's time to go get the materials, I find that this product is no longer available, at least IN STORE and LOCAL (I live in Chicago, so I assume if it's still available I'd be able to find it here). :x

So, I'm looking for alternate suggestions. I have read other builds using roofing tar, undercoating (automotive), etc. Can anyone share the product they used?

Re: Undercoating

PostPosted: Sun Oct 08, 2017 8:39 am
by greygoos
I have used asphalt crack filler. Shake it well and you can squeeze it out from the plastic container then roll it on. 1 quart did the bottom of a 4 X 8 with some to spare.

Undercoating

PostPosted: Sun Oct 08, 2017 9:09 am
by kramergwt
I read a lot on what a mess asphalt emulsion makes and how bad it smells so when I did the underside of the floor before mounting on the trailer frame I primed everything on the bottom with Zinsser oil base primer, caulked all the places where plywood met framing with exterior silicone, primed again, then gave it 3 coats of rustoleum oil base grey. My feeling is that problems hide in darkness and so a lighter color might be better for inspecting. It has no smell and IMHO looks better. There are some pictures at www.flyingwood.com


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Re: Undercoating

PostPosted: Sun Oct 08, 2017 9:10 am
by Stano
I used "Herculiner" on mine ... it was easy to use and did an excellent job. It's a brush on / roll on truck bed liner available at Lowes, local auto parts stores and Amazon.

151359
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Re: Undercoating

PostPosted: Sun Oct 08, 2017 10:14 am
by les45
kramergwt wrote:I read a lot on what a mess asphalt emulsion makes and how bad it smells so when I did the underside of the floor before mounting on the trailer frame I primed everything on the bottom with Zinsser oil base primer, caulked all the places where plywood met framing with exterior silicone, primed again, then gave it 3 coats of rustoleum oil base grey. My feeling is that problems hide in darkness and so a lighter color might be better for inspecting. It has no smell and IMHO looks better. There are some pictures at http://www.flyingwood.com


If I were doing mine over again, I would use kramergwt's method. I used Henry's on my weekender but it has a warning that it could delaminate plywood so I put two coats of Zinsser oil based primer first. The Henry's was good but it was messy. On my latest project, a modified pop-up, I cleaned and sanded the entire trailer frame and wood deck and coated it with Corroseal on the metal parts and then Rustoleum on the wood and metal.

Re: Undercoating

PostPosted: Sun Oct 08, 2017 4:39 pm
by Jdw2717
I used the gloss black rustoleum oil based paint on mine. Three coats on the raw wood and it is still good today after 4 years and 13,500+ miles. I will say that mine is stored in the garage when not in use though.

Re: Undercoating

PostPosted: Sun Oct 08, 2017 5:42 pm
by tony.latham
If I were to build #4, I'd give it a good slopping coat of The Mix (60/40 polyurethane/thinner) and then a coat of oil based paint. (But I've done just the enamel and don't see a problem with that either.)

Roofing tar products served many an old teardrop from back in the day, and I'm sure it wouldn't fail today... but this is 2017 and there are products that will do the same that aren't a black gooey mess.

Keep in mind, I've evolved into one of those fellas that loads the cabin on the chassis when it's about done. Henry's would make a mess I think during the installation. :shock:

Image

:thinking:

Tony

Re: Undercoating

PostPosted: Mon Oct 09, 2017 7:37 pm
by jondbar628
Forget the gooey stuff......A coat of well-thinned (50%-50%)oil-based paint, and another coat full strength is plenty. Any old oil-based will do. (cheap oil-based floor & porch paint is ideal).......Do this BEFORE the bottom is bolted to the trailer.......The bottom of a trailer is the least affected area from the elements. Those who"ve never had a trailer envision water and all sorts of nasty stuff being thrown up against the bottom to rot it out. Simply not the case. The bottom is protected to a great extent by the trailer frame itself. The key is to seal the edges of the ply THOROUGHLY. If the bottom rots, it won't be from the underside, it'll be from the edges.............Note: Many folks use Rustoleum here. A little overkill for this application, but works well: You may want to read the fine print on the Rustoleum can concerning thinning - They recommend acetone for thinning, not mineral spirits. I have thinned with mineral spirits for Rustoleum, but you have to use it within 24 hrs or so. Much longer than that, and the paint continues to thin to a water consistency. Odd, but true....................jd

Re: Undercoating

PostPosted: Thu Oct 19, 2017 10:08 am
by cajundood
OMG....ever try to brush on something, underneath a chassis??? :x
Now you would certainly coat the plywood flooring BEFORE you bolt it to the trailer, but towards the end of the build theres always bolts, brackets and little things that require more sealing after the project is complete.
Rust-Oleum has that cheap rubberized undercoating in a spray can. Costs about $2.50 a can. I buy plenty. works great for me :applause:

Re: Undercoating

PostPosted: Thu Oct 19, 2017 1:59 pm
by working on it
cajundood wrote:OMG....ever try to brush on something, underneath a chassis??? :x
Now you would certainly coat the plywood flooring BEFORE you bolt it to the trailer, but towards the end of the build theres always bolts, brackets and little things that require more sealing after the project is complete.
Rust-Oleum has that cheap rubberized undercoating in a spray can. Costs about $2.50 a can. I buy plenty. works great for me :applause:
That's the reason I used the spray-on undercoating under my trailer, after it was decked, and following each modification where I drilled thru the floor. I used both grades of Rustoleum, and once or twice the Duplicolor brand...whatever was on hand at the time (first at a friend's shop, then at my home garage). It even serves as a sorta loctite on nuts and bolts underneath, preventing them from coming loose. If I made a larger hole underneath, then I coated the exposed plywood edge/grain with PL adhesive, followed with undercoating. I've had no problems with it for 6 years, now.