A few noob questions...

[ecna]

Hello,

I've been reading for a while and am hopefully close to a build, but have a few questions.

Why isn't pressure treated used on the floor? It seems like it would handle the relatively low exposure to moisture but could also dry out better when it did get wet. What am I missing?

Since I'm more comfortable with and have available automotive products, I'm thinking that maybe some fiberglass on the edges, skim coat of body filler just about everywhere, filler primer and automotive paint would be a nice finish. Obviously there's a lot of sanding along the way. Are there any issues the group sees with it?

Thanks,
Eric

[parnold]

Pressure treated wood has nasty chemicals, that you don't really want being released into the interior of the trailer. If you were to completely seal the wood it would be fine.

My first trailer was ply and luan, covered in polyester resin, then primed and painted with automotive epoxy primer, and automotive acrylic enamel paint. I'm doing the same thing on trailer number two.

[ecna]

Paul,

Thanks for the reply.

Pressure treated wood has nasty chemicals, that you don't really want being released into the interior of the trailer. If you were to completely seal the wood it would be fine.

I was thinking of 1/2 PT plywood directly on the trailer, 1x's and rigid insulation on top and then a 1/4 ply top surface. It seems like most go with some kind of a 2x first. What are your thoughts?

My first trailer was ply and luan, covered in polyester resin, then primed and painted with automotive epoxy primer, and automotive acrylic enamel paint. I'm doing the same thing on trailer number two.

I guess if you're doing it again, that says alot.

Thanks again,
Eric

[parnold]

Probably overkill insulating the floor, but many have done it. Structurally it will certainly be enough with what you plan. I didn't because I figure eight inches of foam mattress is insulation enough. The only thing I'm changing between #1 and #2 (besides size) is I am taping all the seams this time. #1 was a speed build, and I did not tape all the seams with fiberglass cloth. One of those seams developed a hairline crack after two years. Other than that, I am very happy with the results and performance.

I am in the automotive body shop supply business, so the stuff is very cheap or free to me, which helped in my decision process also. I did not go for perfection, I do not have any desire to sand that much. Both my trailers will have a texture! If you're ambitious enough, you can certainly create a "show car" finish if that's what you're after.

[jeff0520]

On the topic of pressure treated wood, I have heard that PT wood goes through quite a bit of shrinkage the first year as well. I've heard that the shrinkage can be quite a problem with something built as tight as a TD must be to be weathertite.

[ecna]

On the topic of pressure treated wood, I have heard that PT wood goes through quite a bit of shrinkage the first year as well. I've heard that the shrinkage can be quite a problem with something built as tight as a TD must be to be weathertite.

That's a good point, I have noticed 4x4 PT posts shrink quite a bit. Probably less with plywood, but worth considering.

[ecna]

My first trailer was ply and luan, covered in polyester resin

Paul,

What resin did you use? Did you consider an epoxy resin like Evercoat's Everfix?

I'm reading your first build now. Lots of great ideas... thanks!

Eric

[parnold]

Eric:

I used a polyester resin from Pro Form of Canada. They were a new vendor for us so I was able to get a couple gallons for free. #2 is using US Chemical polyester resin, again obtained for free. I have never worked with an epoxy resin, and I don't know of any advantage to epoxy, so I stuck with what I was familiar with. I did use the two part Fibreglass Evercoat seam sealer to seal off the bottom of the trailer, worked great.

Part of my choice of products is based on what rep owes me what favor. I used a lot of Norton and Sunmight sandpaper on this build, and tried out Upol Gravitex for a second coating on the roof of #1. My paint came from Lusid Technologies.

[ecna]

A couple more questions...

BTW, It'll be a 5x8 trailer and simple 3/4 plywood walls. No sandwich, cookie-cutter, insulation etc.

A high-end lumber yard by me has 5x9 AC Fir plywood. Any reason not to use that over the 5x5 Baltic Birch it seems most use on the 5' wides? I wouldn't have to piece them together.

What wall plywood would you recommend? I think the 3/4 Select Birch A1 is the correct choice.

Thanks again!

Eric

[Forrest747]

The question I hjave is what type of camping are u planning. 3 weather or taking it icefishing ala Wolfgang. Strength wise u will be fine. Are u planning any windows. You will have to find a pretty narrow window but I am sure its out there. Can you get the 5x9 thinner? Thinking for the roof. Doable yes

[ecna]

The question I hjave is what type of camping are u planning. 3 weather or taking it icefishing ala Wolfgang. Strength wise u will be fine. Are u planning any windows. You will have to find a pretty narrow window but I am sure its out there. Can you get the 5x9 thinner? Thinking for the roof. Doable yes

I can't see us in any extreme temps. We've been in some pretty crazy weather in a tent, so this has got to be better than that!

My goal is to get this done quickly as long projects never get finished for me. That's what's driving a bunch of decisions.

For the 5x9 I was specfically asking about the floor, but yes a 5' wide for the roof would be nice, but I haven't found anything.

Profile will be from a 4x8... it's looking Rimple-ish, but with two different profiles.

I'll at least go for the premade door even though it's kinda expensive, it looks great and it will be easy to install. It's for 3/4 thickness. He also has windows as well. I might as well spring for a window on the other side.

Eric

[NathanL]

Fir (Doug fir) faced plywood will check over time when exposed even with a good quality paint, it will also do it when coated with an epoxy but take longer. The only way I know to keep fir from checking over time when exposed is to cover it with epoxy/fiberglass. It's just up to you how much apperance wise it's going to bother you in the long run. Even Doug fir marine plywood will check

[Forrest747]

I didnt say this yesterday. Pressure treated is bad for our application.
at 3/4 inch you are looking at around 1600 ponds of wall strength.

[absolutsnwbrdr]

FWIW... PT lumber also does not paint well until its absolutely dry - probably 2-3 months from the day you bring it home. And when it comes in direct contact with any metal besides stainless steel it likes to corrode them.

[NathanL]

To find a sheet of pressure treated plywood that would work with no studs to help straighten it out would be like winning the lottery. It's not what you want to use, doesn't paint well etc..Pressure treating is meant to deter rot from insects and growths that occur when the material is exposed to wet conditions on a regular basis. Your wood shouldn' thave to deal with any of that, even if you didn't paint it - it shouldn't be staying wet for long periods at all. Go pick up a sheet of 3/4" treated plywood (take another person, maybe 2) it's so heavy no way you really would want to use it and on top of that they normally have a taco like appearance after they are treated, that's why they are generally only used on flooring where they can be screwed/nailed down flat.

When realatively fresh it doesn't cut well either and is very difficult to route, you wind up just tearing out chunks of it rather than cutting it, especially with a router bit.