Plywood floor replacement question

Welcome Luther and hello!

It's hard to answer your question without photos. The walls are installed either "on top" of the floor or "at the side" of the floor.

I am guessing you can piece the floor as long as the carriage bolts anchoring everything to the frame are secure.

The reason this question is hard to answer is because we need more information. If the floor is not attached to the frame properly, the trailer may have to come down further. Be sure that the skins are lifted to assess what repairs are needed.

Here are some pictures of how my trailer is constructed. I would like to replace the floor frame members, the plywood floor, and the lower wall frame members on one side at a time to avoid completely detaching the  body from the frame.  This would require that I split the plywood somewhere near half way across the trailer.  I would add some front to rear support stringers between the existing cross joists to support the plywood seam. I would also like the side anchor bolts to go all the way through the wall frame lower members rather than being covered by them like the current design shown in the picture below.  Does this approach seem reasonable?
Thanks again for any advice.
Luther

I replaced mine the hard way. If you have room and overhead cover it would be easier to totally disassemle it for the repairs. I did not have the required area and jacked up the walls with a floor jack and screwed 2x4s in to support the shell ( after removing the skins).

Many of mine have plywood "only" floors. Most are about 5/8" thick with a layer of tarpaper, coating, or other on the bottom. I think an 1 and 1/2 inch solid floor is going to be way heavier than intended for a trailer.

I would go with an underbelly, floor joists and insulation. Subfloor on top, could be as thin as 3/16ths if you plan on T and G flooring...

I was just thinking the space was already there, with the cardboard.

1/8" masonite makes a good belly. It's pretty tough, surprisingly. I paint the underside with waterproofing roof sealer, easy clean up, available at HD.

So then add joists the thickness of the cardboard and insulate around/in between. Should only need 3 running up the middle and whatever is used as a sill. I like foam better than fiberglass in a belly; doesn't absorb water.

You are making a sandwich, belly, insulation/joists, then subfloor. Depending on the thicknes, you use 1/2 to 3/4 ply. The joists give something to anchor the ply to. In other words, you have a space to work with, use it rather than make it solid. JMO, insulated floors really help.

Here's a link to my Cardinal build:

s189.photobucket.com/user/vikxphotos/library/58%20Cardinal%20Two%20into%20One?sort=6&page=20

You can see the belly going in on page 20, then 19, 18, etc to follow the progress.

The Masonite has some sheer strength but is basically there to hold the insulation in place and keep debris out of the belly. It covers the entire frame before the joists go in.

The joists are installed with carriage bolts. On the Cardinal, I bolted thru the joists/belly and frame metal. The upper subfloor is installed with 1 5/8 screws; a very strong and secure attachment. If the bolts go thru from the subfloor, they must be inset and filled with floor leveler to allow the top luan to lay flat. I've done it both ways. I do not like having to inset the bolts in visible areas (the middle of the floor). In the dinettes and under the bed doesn't matter.

The underside photos show smaller hexhead screws attaching the belly to the wooden joists. They are similar to metal siding screws. The seams were painted with the waterproof sealant.

To Clarify: the bolts you see attach the joists to the frame. There are also side bolts holding the bottom walls to the sills. The smaller hexheads hold the belly and prevent sags. (belly was also stapled)

Hope this helps. Happy to answer more questions.

I did go a bit overboard with the carriage bolts on the Cardinal... the holes were there tho. LOL. The frame is not original to a Cardinal (late 50s Cardinals have weak, usually broken frames). We modified the frame to fit a canned ham body; also widened and lengthened the body. It was an intense but fun build. Lots of thinking went on.

My 52 Hanson has about 2 feet overhang in the back with no support. The joists do go to the back and add some support. I think the general idea with old hams is that nobody would be walking back there; just the bed...Oddly, the Hanson walls were bolted on top of the frame. Cardinal walls are on the side; bolted thru the sill boards. Both are very strong.

Here's a photo showing the Hanson frame. It did have two metal runners to the back two by, then 3 joists in the middle, bolted to the frame. All provide some support to the butt portion.



Here's the link to the page of the Hanson Story where the floor/frame is:

s189.photobucket.com/user/vikxphotos/library/The%20Hanson%20Story?sort=6&page=5

You can scroll thru the pages to get a better idea of what was done. The belly in this particular trailer is Coroplast, a type of corrugated plastic. (like cardboard) It is 1/4 inch thick and was inset into the frame. I prefer to lay the belly as the Cardinal.

Be sure you check your frame very closely for cracks and rust thru. If it's sound, extra joists should add strength. It's also possible to add cross bars from side to side and bolt them rather than weld. I've bolted a few when welding would have endangered the trailer body... Can you imagine welding with cardboard stuffing? Yours is the only one I've seen with that.

You have a RARE TRAILER! Keep us in the loop.