Floor

[asianflava]

I am getting ready to skin my floor. I was going to skin the underside with 1/4 ply and the top with 1/8 birch.

My thinking was that the 1/4 ply would have more impact resistance from whatever was kicked up underneath the trailer. I weighed the pieces and the 1/4 ply will weigh as much as all the other floor components.

I welcome everyone's opinions.

[mexican tear]

If you seal the bottom of the floor, will it not invite water to stay on the inside allso?

It may be better to seal it with asphalt.

My 2 cents worth

kai

[Ken]

Kai

Enjoyed your photos, I have just started, floor probably 75% complete and exterior sides, windows and doors are cut out. I am keeping track of my time, 33 hours so far. Do you have any idea how much time you have in the woodwork, not the steel work? I’m interested in your time from the floor to skinning the top. As for my floor it’s ¾ treated plywood covered with ¾ insulation, top cover undecided. The bottom of the floor is covered with roof cement, black and gets on everything.

[mexican tear]

I have no idea how much time I have in the Mexican Tear. I am retired and do not keep track of time. I can tell you, it is a lot.

I definetly am not a cabinet maker, nor am I a hatch builder. I have built the hatch three times. It is pretty much what I want this time. Most of the time is in the details, and I am learning them as I go along. Mistake after mistake.

Thanks for the good words.

kai

[R Keller]

asianflava:

As you know, I used 5/32" (essentially 1/8") plywood on the bottom of my floor. Initially I was a bit leary because of the worries that you express. To ease my mind, I made some test panels and then proceeded to attack them with hammers, screwdrivers and the like. It was fun and informative! They were very tough. Not as tough as, say, 3/4" solid plywood of course, but the Finland Birch, like Baltic Birch, has plys that are all about the same size, so it is a lot tougher than standard-issue 1/8" big box store plywood. The foam seem to distribute the force, so things don't "punch through" as easily as you might expect.

To realistically to model rocks hitting the underside of the floor, you could make small test panels and shoot rocks with a slingshot at them! Tell us what you find out!

For my floor, even if a rock manages to do some damage to the underside, I can just patch it up with a little asphalt emulsion. Although, it's hard to imagine a rock, striking anything other than a undamaging glancing blow.

Of course, it's a whole different matter if I run over something large that don't have the clearance for....

Rik

[Dave M]

I would avoid sealing the floor in like that if possible. I don't think the issue is weather or not you will get a puncture but that water and road salts will infiltrate the outter layer and start rot inside the box you have created. You can spen a lot of money and time sealing it up real good but in the end it will probably be easier to leave it open underneath. That would mean you woudl need to use thicker ply for the floor, which I think is a good thing, even if you seal the floor underneath.

1/8" may feel stiff in the sandwhich but it wont stand up to much abuse over the long run. Your foam will compress as time goes by and the floor will sag inside. Once you lose suport for the thin ply it will easily puncture or crack.

I would do a 1/2" -3/4" exterior grade ply with a frame of 1"x2" or similar bolted to the chassis. Coat it in roofing asphalt, glue and screw in foam insulation.

JMO

[BrianB]

After looking at a few trailers, I've gotten to like the idea of putting wire mesh between the cabin and trailer.



It'll give that extra bit of protection against those things you don't intend to be running over (debris, small animals, small childre....whooops) while adding support to the floor so your frame doesn't have to be very thick.

[R Keller]

I would avoid sealing the floor in like that if possible. I don't think the issue is weather or not you will get a puncture but that water and road salts will infiltrate the outter layer and start rot inside the box you have created.

I could be wrong, but what I think asianflava is talking about is building a sandwich with 1/8" ply on the top 1/4" (or 1/8") ply on the bottom and wood framing and styrofoam in between. How is water going infiltrate that any easier than solid plywood? Just seal the bottom piece of plywood with some asphalt emulsion and you're all set.

Dave: where are you talking about "glueing and screwing in the foam insulation"? Are you talking about a sandwich with the 3/4" or 1/2" ply on the bottom?

Rik

[asianflava]

I could be wrong, but what I think asianflava is talking about is building a sandwich with 1/8" ply on the top 1/4" (or 1/8") ply on the bottom and wood framing and styrofoam in between.
Rik

Yes, you are correct Sir. Thanks for your input Rik, I will continue on with the 1/8 baltic birch for the underside.

I would avoid sealing the floor in like that if possible. I don't think the issue is weather or not you will get a puncture but that water and road salts will infiltrate the outter layer and start rot inside the box you have created.

When you sandwich or laminate the panels together, all the mating surfaces are covered with adhesive. The moisture should be contained by the foam.

I won't be pulling the tear whenever there is a need for road salt hopefully, I won't be driving at all when road salt is needed. I am looking into sealing the edges with either thinned epoxy or CPES. I am also looking at different things for the undercoating, either asphalt emulsion or spray bedliner. Depending on the coating, it too will provide impact resistance. Cars that have no undercoating typically have dings from pebbles that get kicked up cars that have undercoating usually don't.

[Dave M]

Rik, yes I am referring to the sandwich method in my response. I should clarify, I do know the sandwich method will work just fine for the floor but I think that it may be more work than needed and if not done properly will invite disaster. Making sure that the sandwich is protected from the harsh environment under the chassis means sealing it inside and out (not just the outside). To do it properly I think you would need to coat all the inside surfaces in paint, epoxy, cpes or similar before closing (the glue alone is not enough of a barrier). Then coat the outside in roofing tar or some other tough sealant. Water will be present in the air trapped inside the space as well as the foam itself. Water can, and will eventually find a way inside the "sealed" space over time especially if the outer skins are only 1/8" or 1/4" thick. But ultimately my main reason for opposing the method is its unnecessary.

You would save time and money by just using a single sheet of 3/4" exterior ply for the floor. It could be framed with 1"x2" if you want more wood to secure the side-walls to but its not required. Coat the bottom of the floor and sub-floor with roofing tar and then simply glue & screw in your foam insulation (that means just what it says). The foam may take some abuse over time but will stand up pretty well I think. As it deteriorates it can be replaced. The insulation factor will be nearly equal and you will be able to inspect the whole underside for damage, no hidden dangers. Additionaly I don’t think 1/4" ply on top will make a suitably strong floor. Over time the foam will compress inside the box leaving the 1/4" ply unsupported. It will sag and may even crack. Even if you do the sandwich, I’d up the top ply to 1/2". If your building to last don’t skimp on the floor.

Asianflava, to answer your follow up post more directly, cars w/ undercoating are usually made of metal not 1/8" ply. All you have to do is drive over one errant branch from some guys clipped hedge @ 25mph and you could puncture that ply. You’d never know, water gets in and your bottom starts to rot. Probably unlikely, I know. I’m being overly cautious and a bit of a devils advocate here, just trying to promote what I see as an easier, cheaper, safer method that will work just as well.

Dave

[R Keller]

Dave, thanks for the clarification. My turn to play devil's advocate now. Foam on the underside of the plywood? That does seems strange to me. Can picture little chunks of it gone and littering the roads in no time. The last thing I'd want to do is crawl under there and replace the thing over time. Any labor you save in the short term would be lost in the maintenance.

BTW, my sandwiches are glued with epoxy. No moisture getting through there. And Styrofoam is rated at 25 lbs./sq. in. compressive strength, so I don't think there's much worry abput compressing the foam over time. But I could be wrong. It's always good to have differing viewpoints. So carry on!

Rik

[Ken A Hood]

Has anyone considered using a rubber membrane on the road side of the floor? The kind that goes down on a roof to stop ice dams? I'm considering using it, and wrapping it up the sides at the floor/wall connection, to make the joint watertight.

[angib]

BTW, my sandwiches are glued with epoxy. No moisture getting through there.

That's mighty big talk, pilgrim! (please supply your own John Wayne accent)

I wasn't going to intervene on this subject but Rik's comment was too much temptation... Epoxy is great, but not that great. I've seen water leak straight through epoxy laminate (though not vacuum-bagged laminate). If you think tiny amounts of water are not wicking into the bottom of your floor by capillary action (and the voids in your incomplete epoxy-ing) every time you drive in the rain, I think you're mistaken.

BUT, does it matter? I don't think it does. While I would agree with Dave about trapping moisture in, I also think a (nominally) waterproof floor is the best way to minimise how much moisture ever gets in. A double-skin floor presents so many less joints through which moisture can easily travel.

On this subject, how many of us once used to think that wrapping insulating tape around car electrics was a way of keeping water out? And how many of us now think that it's a way of keeping the water in, once it gets in?

Andrew

[ahjones3]

I'm new to Teardrops, but have some construction experience. Correct me if I'm wrong, but isn't sealing both the top and bottom of the floor like having a wall with 2 vapor barriers? That usually means trouble.
For my Cubby floor I used pressure treated 2x4's ripped into 2x2's. I covered this frame with 1/2" pressure treated BC plywood for the floor deck. On the dirty side, I glued & screwed 1" foam between the 2x2's. The Dow blue stuff or the OC pink stuff is pretty impact resistant. No places to trap water, and no need for the yucky roof coating. If I do run over a tree branch, it might put some gouges in the foam, but it wouldn't be the end of the world.
In some areas they build basement walls out of these 3 products. If it can last for 50 years buried in the ground, it's probably good enough for my trailer.
Al.

[R Keller]

I wasn't going to intervene on this subject but Rik's comment was too much temptation... Epoxy is great, but not that great. I've seen water leak straight through epoxy laminate (though not vacuum-bagged laminate). If you think tiny amounts of water are not wicking into the bottom of your floor by capillary action (and the voids in your incomplete epoxy-ing) every time you drive in the rain, I think you're mistaken.

Thanks for the intervention Andrew! OK OK, so maybe I overstated. Epoxy is not totally waterproof. But since the bottom sheet of plywood on my floor is coated with two coats of asphalt emulsion, I think I'm about as safe as I can get. Any moisture that gets through that would then have to get through two glue lines in the plywood (waterproof glue because Finland Birch is exterior grade), and then a 20 mil thickened epoxy layer before it hit the foam.

I'm way more worried about moisture getting under the roof aluminum and staying there, rotting out the roof plywood over time. I haven't heard this subject discussed. Anybody have any thoughts about this?

Rik