Sub Floor vs. Direct to trailer frame

[Vanq]

Most of the build logs I read use some sort of a sub floor interface between the floor and the chassis. In my build: http://tnttt.com/viewtopic.php?t=45820 I discovered that Eaton simply riveted the 3/4 flooring to the chassis directly without the sub floor, and it seems to have held up for 45 years or so.

What are the benefits and drawbacks of going with a subfloor vs bonding directly to the chassis?

[OuttaHand]

I bolted ply directly to the frame, then put on 1" foam, then put 3/8" ply over top of that.

I did this because I wanted insulation in the floor. One of the things that can happen while camping is condensation on the floor. The underside of the trailer will cool overnight. Your breath will create moisture inside. When the moist air hits anything that is uninsulated, it will condense and get wet.

I did not want condensation building up under the foam mattress, etc.

You can see my build, with lots of pics of the floor, here:
http://webpages.charter.net/outtahand/littletow/index.htm

[greekspeedoman]

I've done both.

3/4" ply straight on the frame works just fine. Didn't insulate the floor, that is what a mattress is for. I live in the NW and camp in 20 degree weather. No problem. No condensation. No Sweating.

[Oldragbaggers]

I will insulate the floor.

We lived on boats for years and found that our body moisture and heat moved through the mattress, hit the cooler surface underneath (in our case, cold uninsulated gelcoat) and condensed. What we ended up with was a wet mattress every single morning in cooler weather. We had to prop it up every day and let the underside dry out, until we added a layer of insulation underneath, then no more problem. I know wood, by nature, is "warmer" than gelcoated fiberglass, but still it's an experience that has stuck with me and for the peace of mind and a better chance at a dry bunk, the extra step of building a subfloor is worth it to me.

Becky

[Deryk the Pirate]

I sort of insulate the floor. 1" plywood bolted directly to the frame, then 1" foam on top then a carpet...should be prettywell insulated!

[Thawley]

3/4" ply straight on the frame works just fine. Didn't insulate the floor, that is what a mattress is for.

What he said.

Becky's experience is the opposite of mine. We slept on 5" of foam without issue. A spring mattress might be a different deal, though.


.

[Oldragbaggers]

3/4" ply straight on the frame works just fine. Didn't insulate the floor, that is what a mattress is for.

What he said.

Becky's experience is the opposite of mine. We slept on 5" of foam without issue. A spring mattress might be a different deal, though.


.

I have to assume then that the difference is the wood as opposed to the fiberglass.

[madjack]

I build with a single layer of ply directly on the trailer frame with a 5" foam matt on top...CONDENSATION can be a problem...to stop this, get a sheet of foam(I prefer blue) and tightly fit under matt, this will eliminate the condensate problem as well as any problems with trapping water in under floor insulation.........
madjack

[Oldragbaggers]

Good idea MadJack.

[Gaelen]

I was wondering if a mat like this puzzle mat - each foam square is about 1/2 inch thick x 24" square - would work on top of a plywood floor for a combination of insulation and mattress/subfloor protection from condensation. The floor is finished underneath the tear, but the sleeping compartment side is raw wood.

I've used these foam squares in other applications as anti-fatigue mats. They're designed to keep heavy exercise equipment stable and protect the floors they sit on. The squares are easy to trim to size, edge clean, clean up well, and don't absorb water (great for spill protection.)

I'll be putting in a mattress on top of the mat. But rather than cover the whole floor, I'm thinking of using either a 30" or 36" cot-size mattress + body pillow combination, so that the mattress is more like a sofa when I'm not sleeping on it. The tear is a 4x8, so a cot-sized mattress will leave 12-15" of floor exposed. I like the idea of covering the raw wood with the foam mat or some other water-resistant covering. Just don't know if I should seal the inner surface of the wood first - if I were putting in a piece of linoleum (vinyl) I'd go right over raw floor.

Thoughts?

[madjack]

...those puzzle mats will work just fine...............................................

[Gaelen]

You gotta love a cheap (um...inexpensive...) solution - $19.99 from Walmart is perfectly reasonable. But I saw a double sets of those mats (12 pieces that are 24" square) at the local thrift shop for $5 each. That's when I did the math and realized that they'd cover a 4x8 tear's floor easily. So it's off to the Thrift store in the morning.

Since the mat is heavy enough to hold its position without glue, should I put a coat of sealant down on the raw plywood side of the trailer floor first?

[madjack]

I would...actually I seal everything..............................................

[goteeguy]

I'm just about ready to start my build. My question is: If I secure my 3/4" floor directly to the trailer frame, is it OK to then glue & screw the 3/4" walls into the outer edge of the flooring? Or should I elevate my flooring on 2x2's to allow bolting my walls through the 2x2's?

Thanks,
Ken

[48Rob]

Ken,

If you bolt your flooring to the frame, you can attach 2x2's to the top of the plywood, to have something to attach your walls to.

Rob