Attaching a foam wall to floor

[Don L.]

I plan to build a canned ham foamie and since it is tall I am concerned about having a good strong wall to floor connection.

I did a sketch which hopefully I can post and will explain my idea, tell me if you think it would work.
On my trailer the plywood floor extends out past the frame, there are brackets that extend out from the frame. The total floor dimensions will be 78" x 125".
Note that there is a 2" x 1-1/2" piece of wood glued to the bottom of the foam wall that is wrapped with the canvas, I didn't indicate that in the sketch.

[Don L.]

I meant to mention that I have read a thread about gluing L flashing to the foam and then to the floor. I'm sorry I don't recall who was doing that. The flashing idea looks good but I cannot find anything at the lumber stores around here that would work well, it's either too thin or has some odd shape to it.

I should mention that on my sketch I would cover the wall/floor joint with some kind of metal strip on the outside, not sure what though.

[KCStudly]

That's essentially what I did, except I have a built up floor so used longer deck screws to get up thru; and I'm building off of the trailer so will wrap the side wall skin under the floor. My sills are 2x2 cedar, but 1-1/2 would have been plenty. (I did build this up a little higher in the galley area, adding another 1x on top to give enough for the cooler glide to screw into.)

I would not rely on trim alone to seal the edge of the floor ply. The edge of the ply is the most susceptible to water intrusion, so most people like to wrap that too.

Having the hard edge on the bottom of the wall core really helped to protect the foam during the building process and I'm really glad I did it that way.

You can see one of my wall cores here (from page 56 of my build). In the pic the wall is standing up a little way back from the edge of the floor just for the sake of the clamp keeping the wall from falling over for the photo op, but it helps to show how the wall sill is separate from the floor (floor being used as a work bench at this stage of the build).

[GPW]

Actually we found just gluing the foam to the floor works fine , and the reinforcing strip and outer skin hold it firmly to the floor ... But anything extra you feel is needed is perfectly acceptable ..

[Don L.]

Thanks for your comments. As I have heard GPW say before 'do what ever you want to' which I guess is what you have to do since everybody's trailer is different.
KC, thanks, I haven't figured out a great way to protect the plywood edge yet. Maybe wrap it with PMF before the wall goes on top?

I'm slowly figuring out how to build this thing. I'm so glad to have found this forum and the wealth of information!

I could explain how I am going to proceed but I hear that you all really like to see pictures of a build and since a picture can explain a thousand words I think what I'll do is wait and post some pics once I get going.

[Don L.]

I am finding more threads about attaching the walls to the floor which is helpful. I don't want you guys to have to keep repeating ....!

[KCStudly]

It would be structurally better if you wrap the floor and wall together, or at least add a strip of cloth wrapping them together. Have you thought about building the cabin separately and then placing it on the trailer? You could use temporary boards screwed to the underside of the ply (set back from the edge enough to pre-cover). These temporary boards would stiffen the ply enough to hold everything flat while you are building, yet not get in the way. Then you can use the floor up on saw horses as a work bench to build the walls on.

Building the cabin off of the trailer has many advantages; being able to set your work height to suit the situation; not having to work around the trailer tongue or fenders, etc. I realize that you are planning a larger camper, and it would also depend on your workshop situation, but don't rule it out as an option w/o giving it some thought. Building from the inside out is always better. Even on the big manufactured rigs that's how they do it these days; it's just more efficient.

[rowerwet]

I drove nails up through the floor along the foam to floor join. They mostly just kept the foam pinned in place till the GG set. I did rout the lower edge of the floor with a round over bit to ease the fabric transition from wall to floor.
Once the foamie was assembled, I used a trolley jack to raise it all up on 2x4's, above the frame. This let me wrap the fabric under the floor with no problems.
I can't imagine you need more reinforcement than that. Though you could run a quarter round inside along the floor to wall seam, fully glued to both.

[Don L.]

KC, the camper won't be removable. My plan is to attach the floor then attach the pre-made side walls, then the roof. I like you're idea about keeping the edges of the floor (3/4" plywood) flat. That plywood is just floating in between the steel brackets that come off the main frame and the ply won't want to stay flat without some stiffening.

This foamie is sure keeping my brain working! My other issue is the idea of dropping the floor in between the main frame, that way I can lose 3-1/2" from the total height. I would need to cut out one steel cross member in the frame. It's a 1968 Tag-a-long with a 3,000 lb. axle rating. I think the frame is stout enough to handle it. I guess that's another thread!

[GPW]

Starting another thread isn’t really necessary ... This one works fine ....

Got any pics of your trailer .... ??? Around here we do love the

Messages from the past ... viewtopic.php?f=55&t=44225

[KCStudly]

Your wall should stiffen the floor just fine once installed, especially if you go with the wooden sill. The suggestion for the temporary stiffeners was just if you decide to use the floor as a work bench off of the trailer frame.

[Don L.]

I hope these 3 pics work.

Edit-sorry I tried to get better pics on this post. Go to page 2, I think I can do it.

[GPW]

Don , Yes .... thanks .... trailer looks good , you already have the outer supports ...
Just remember , on a Foamie , "everything is part of everything else" ... all working together as one ...

[Don L.]

Having difficulty getting better images up. You might have noticed, someone with welding skills has modified this. They extended the rear bumper back about a foot and also welded some leveling jacks all around. I like that!

[Mary C]

Don Welcome to the foamies. I like your trailer and note it is somewhat similar to mine. I am not sure where you live but if youre close I can show you my finished trailer. Putting your area or city you live in or near gives us the information for so we can help you secure parts and pieces for your build. I think once you secure plywood on the trailer you can secure the sides to th plywood with glue, you could use pegs or dowles through the plywood into the foam also then secure the canvas around the foam under the plywood. I live in the south and i had put the canvas under the foam and once the mold had gotten hold I had to completely re do the canvas. I had to take off the top part and unfold the canvas and wash then re glue the whole thing. It was a learning thing. If you live in the south mold and mildue can creep into everything. Good Luck

Mary C.