Please criticize my building/waterproofing ideas

[Mikedaub]

I must say, getting to this point has been quite the process. First, starting in January, I was going to just buy a teardrop from Little Guy, I actually talked my brother into getting one, which he loves. I decided that was going to be too costly and not enough space. I need something that I can drag a bunch of gear to mountain bike races (multiple tables and 10x10 tents), so reworking an enclosed cargo trailer was next on the list. After that fizzled out, I found this website and saw what people were doing. After a bit of time of deciding what to do, on Friday, I clicked the "submit order" button and a brand spankin' new Harbor Freight trailer is on its way to my house. Thank goodness, I finally made the decision.

Now is where this great community comes into play. I have read and checked out pictures of TONS of things on this site, but am still a tad confused.

For building the unit, I really don't think it will be all that difficult. I plan on going with a weekender/simple design and while I might not put all the best finishing touches on it, it will be functional, a bit lower cost and better yet, something I did with my wife that we will spend years enjoying. I have helped to build 2 house and re-frame an apartment, so while I am not the best carpenter in the world, I feel like I can make this one happen.

The main thing I am confused about is the water proofing. Man, there are so many ways to do it from lacquer, epoxy, fiberglass and roofing tar. To be honest, I still don't know where the roofing tar comes into play. Either way, I wouldn't mind if someone would criticize my choice of building/waterproofing materials.

I figure for the 4x8 floor, I was just going to get some quality pressure treated plywood and give it a nice coating of Thompson's water seal. I thought that would give a nice baseline. For the outer shell, same deal. Thinking 1/2 pressure treated ply (something with a nicer finish as well) with the water seal on it again. When all is said and done, thought about a few coats of lacquer to finish it off, also, maybe some paint. We will see when I get to that point. Thinking 2x2 pine framing stuffed with some insulation and then a nice luan or something in the inside just to cover up. All the seams will be caulked with a silicone sealant and thought about putting a nice L channel wood/metal trim around the edges so you don't seem them as well. (don't ya love my vocabulary for the technical stuff??) Does this sound like something reasonable or am I WAY off base. I know it might not have the nicest finish to it, like some of the sweet woodies on here, but this is my first project and I am sure bigger and better things are on the horizon if this one works out well. I want to get something that works and is completely functional first, then I will work on the looks.

Thanks all for the help and yes, I am charging up the camera battery to make sure I document this entire process.

[48Rob]

Hi Mike,

Congratulations on your decision to build.

Buying, or building, one isn't better, or worse than the other, just a choice.

Choosing to build means you must enjoy the challenge!

Using treated plywood, or any treated wood that will be "exposed" to a living/eating/general use area is in my opinion, not wise.

While treated wood can last a little longer than regular untreated wood when exposed to moisture, it can still suffer damage.
But worse, are the potential fumes and poison you'll be exposing yourself, and family to...not to mention, it smells

Roofing tar is generally used to waterproof the bottom of the plywood floor, the part exposed to road spray, as it can withstand road debris better than just paint.

The rest of the trailer is generally painted, varnished, epoxied, or covered with a waterproof material like aluminum or plastic/fiberglass.

To really "waterproof" your trailer, all "joints" like the area where the floor meets the walls, and where the walls meet the ceiling/roof must be sealed tight.

The plywood, where exposed, must be well sealed with the material of your choice.
If you choose to just paint the top and sides instead of using aluminum or other coverings, that is okay, just seal them well.

How well must it be sealed?
ANY EXPOSED WOOD must be 100% waterproof.
Water sealer works okay for fenceposts and decks, but usually must be applied every 6 months.
It makes wood a little more resistant to water, but does not waterproof 100%
You should be able to expose any part to water, and NONE must penetrate even just a little.

If you do it right, it will last a long, long time.
If you just paint/seal "the parts you can see" it will begin to rot in months, and be ruined in a year...or less.

Nothing to worry or fuss over, it is pretty basic and simple.
Study up a bit, then do the job right and you can enjoy your trailer for years to come with no worries.

It doesn't have to be a showpiece, or perfect in any way, but it should be made safe, and must be made waterproof!

Rob

[mikeschn]

Waterproofing... good to see you are giving it the attention it deserves...

For the bottom I like the roofing tar. Can't beat it for the price.

For sealing the plywood sides and top, I use CPES from the rotdoctor.com

I then typically paint over that with Uniflex 255.

However since that product will be going away soon, if it hasn't already, we will need to research other options. And there is a thread started that is exploring that.

Mike...

[caseydog]

I would also say you should NOT use pressure treated wood on your camper. It is not healthy, and in my experience, pressure treated lumber is good where there is contact with the ground, but up off the ground, it is not a good choice. I have used it on a deck, which was a mistake, and for fence stringers, which was also a mistake.

Make your floor with any non-treated plywood (I used birch), and coat the bottom with roofing tar, like Mike said.

Pressure treated wood has a purpose, but IMO, a teardrop build is not it.

CD

[Miriam C.]

What they said, and leave off the Silicone. Use a glue for seams and a different adhesive/caulk for the trim.

[Mikedaub]

Well...wow. thanks. I am glad I made the post because I was WAY off base. Thanks for the quick replies.

First off, from what I gathered, it seems as if pressure treated wood is very bad. Got it.

Ok, seems like some roofing tar on the bottom sheet, check, then time to buy some things from the rot doctor. Looking over their site and what was said here, it seems like I will have a rough square footage of about 128 sq feet. For that, I will need to buy 2 gallons of the CPES (http://rotdoctor.com/products/cpes.html) and then it seems that I will need 3 gallons (for 2 coats) of the UNIFLEX 255 Aliphatic (http://rotdoctor.com/products/uniflex.html). According to their order page, it is still available. Hopefully I squeaked in under the wire and they still have it in stock.

After the Uniflex, I can just paint it to what color and throw some sort of finish (varnish or something).

Thanks again for the info, it seems like I have been pointed in the right direction and will probably order the stuff up from the Rot Doctor in the next day or so people agree that I am in the right direction...