That floor to wall join ...

[oz97tj]

That all makes sense. I think the foam floor is cool, if it will work. Depending on the spacing of the frame rails, I'm thinking you'll need more than 1/4 ply with the foam.

Do a simple test with some foam and lay it on the floor on top of some spaced out scrap 2x4s. Then you and the wife climb on it. Maybe it's because I'm a fatty, but I was shocked at how much 1/2 ply sagged between my frame crossmembers. Then again, I don't have many crossmembers because I was concerned with saving weight.

So, you can add crossmembers every 16 inches (or closer) to not have any sag in the floor or you use thicker wood for your floor and use less crossmembers. It's probably a wash either way you look at it, but I'd be curious if someone actually figured out weights of the metal used for frame vs wood used for floor.

Then again, if the frame will be a multi use trailer anyway, then more crossmembers may be needed for whatever else you have planned.

Sorry, just thinking out loud...

[Conedodger]

In Pods8's build of a truck camper where he is doing the same as i want to do on a truck, he has used 1/2 ply cut in 2" strips fitted on end like a grid to make the floor, he has also put wood blocks at points where he is bolting down. By cutting opposing slots in the ply strips so it all locks together it would hold up to a lot of weight using far less wood, the foam keeps them all in place.



1/2" ply end on is very strong and the foam and glue (Epoxy) holds it all together. Around the parimeter he has rebated a 2" wide piece of ply horizontal and a piece behind it standing on its edge.

He is using 1/8" ply as a floor on top and i think it will be very light and strong and the design makes it so the foam is taking very little stress.

His build is very interesting and can be seen here

http://www.expeditionportal.com/forum/threads/58926-POD-Homebuilt-foam-core-fiberglass-skin-pop-up-camper-build-thread

I think two of the things thats making his build very interesting is he is using small blocks of foam with the 1/2 on end strips of ply boxing them in rather than just on one edge. The join using epoxy of the Foam | ply | Foam is stronger than just foam.

Also by rebating the edge with a router and putting in a flat 1/2" piece of ply he is building it like a flat pack and when ready he will fix it all together before he skins it.

The build is not far on but has some great points and he certainly did a lot of research.

[swampjeep]

That all makes sense. I think the foam floor is cool, if it will work. Depending on the spacing of the frame rails, I'm thinking you'll need more than 1/4 ply with the foam.

Do a simple test with some foam and lay it on the floor on top of some spaced out scrap 2x4s. Then you and the wife climb on it. Maybe it's because I'm a fatty, but I was shocked at how much 1/2 ply sagged between my frame crossmembers. Then again, I don't have many crossmembers because I was concerned with saving weight.

So, you can add crossmembers every 16 inches (or closer) to not have any sag in the floor or you use thicker wood for your floor and use less crossmembers. It's probably a wash either way you look at it, but I'd be curious if someone actually figured out weights of the metal used for frame vs wood used for floor.

Then again, if the frame will be a multi use trailer anyway, then more crossmembers may be needed for whatever else you have planned.

Sorry, just thinking out loud...

I will have to examine the panels I have out back, but they were from a manufactured camper floor, they are somethign like 1" foam, inside a frame of 1x2, with 1/4" plywood, when I fist stood on the plywood I never would have guessed how light it was, and that it was mostly foam, then I started cutting it to get it off teh traler frame, I used the trailer frame for a util trailer which is now sold... but when I cut the flooring up, I was shocked. I saved it, I wish now I would have cut it in larger pieces.

[Conedodger]

I think Fridge vans use a foam floor as well so it must be strong enough

[GPW]

There are many different densities of foam too ... some quite Heavy and rigid... maybe denser material for floors ???

[DJT]

Cone, thanks for that link! That's a great idea for the floor, I may have to figure that into the build.

Dave

[Wobbly Wheels]

Yeah, thanks for putting that up Cone. That's exactly what I was on about.

I think the way to go might be to rip strips of 1/8" ply across the grain (1"X 4' strips) so that when you stand them on edge, the outer veneers have their grain running vertically. This ought to give you a lot of compressive strength, like the shear web in a wooden aircraft wing.

One question I have is whether you'd get a better bond using a panel adhesive and a notched trowel, or using epoxy for the extra strength in the wood-to-wood bond...

I like Pod8's idea of using the floor as a work table for building the other panels. That would give you some good (albeit subjective) feedback on it's ability to do the job.

[Conedodger]

Idea that just might work:

I have been thinking about the floor in this picture



Obviously the foam is used for insulation and for weight saving. In this case he is covering the floor with 1/8" ply.

Its a great floor but took 27 hours for finish which compared to Eagle and GPW they almost completed a Foamie body in that time.

I then started thinking, once its skinned its just a very thin box with partitions inside. Each partition is filled with a cut piece of foam. However he spent ages glueing it all together and filling all the gaps so it does not move. Each stage had to be clamped until dry.

My idea is to do the same wooden grid and fit the top and bottom but without any foam inside. I will then inject spray foam (Cavity wall insulation) through small holes in the underfloor to fill the voids. The holes will be simple to fill.

Anyone who has used spray foam will be aware it sticks to almost everything, and if there is an area you dont want it to stick to simply cover it with cling film.

Spray foam is available in aerosol cans so no mixing, very little waste and no need for a trailer to fetch it. Its available at every DIY store and even on ebay.

Once its injected through the holes it expands and would fill the void in the same way as cut foam but with one huge advantage.

One of the biggest problems with pink and blue foam is a suitable glue and having to clamp it together while it dries. TB2 does not work where it cant get to the air and GG is a bit messy and foams so has to be cleaned up after the clamps come off, and epoxy has to be mixed and weighted down.

pods8 did this



Once you have made your floor box (or wall if you want) you would inject it and as the spray foam expands it seals all the holes and at the same time sticks like "S**t to a blanket" to glue all the parts together in every corner.

No filling, No clamping, no paving slabs, no leaving it in the same place until dry, you could inject it and lift it up and put it out of the way and it will dry in an hour.

Can anyone see a problem with this and will it still be a foamie?

[Ratkity]

If it's a wall, it's an insulated tear with traditional wall.

If it's the floor, it's an insulated floor LOL.

The idea of a foamie is that you use foam as the wall and canvas as the supporting skin once it is glued in some way to the foam.

I see the same problem with spray foam as with using gorilla glue. It expands and gets messy. Also, you'll be using LOTS of cans of foam to fill all the spaces. There's a chance for voids as well.

Hugs,
Ratkity

[Ratkity]

I think Fridge vans use a foam floor as well so it must be strong enough

I believe there's a compression number on the foam I used for my solar panel. I'm sure you could find the numbers somewhere.

Hugs,
Ratkity

[Conedodger]

Ratkity:

They use expanding foam in cavity wall insulation without any void problems, they simply put several holes and spray in one till it gets to the next one.

I cant see there being a lot of mess as its all inside, yes around the holes but if you have plugs or tape you can stop it coming out.

I do understand your point about the walls but the idea was to make a TD in a thrifty manner, the cloth skin came later.

I think in my build i would use both types of foam.

Cost: have a look on ebay, its cheap and available and a lot of us cannot find 2" foam.

[Tx River Rat]

Most foams are rated lbs to the cubic foot.
! lb per cubic ft normally being the lowest.
Ron

[Jerry & Molly]

Hi All, I'm a newbie here and have been watching the foamie thread with great interest. I was wondering why the floor has to be attached to the walls? I can understand it in a conventional build or one where a person might want to slide the camper in or out of the trailer. But if you had the clearance or depending on how your fenders were done. Couldn't a 2 " (inside size) be welded around the trailer, possibly around the door frame then the foam gg'd to it? That would equal to about 6" of glued surface, 2" on each side and 2" on the bottom. 2" by 1/8" angle iron weighs 33# per 20' section so the weight increase wouldn't be that much.

[Conedodger]

Not sure if i quite understand, all the Foamies so far have a ply floor shown here



A piece of angle welded to the chassis would be where the black line is so if the floor is 3/4" ply its only adding 1 1/4" up the side

Also anything on the outside would be a leak waiting to happen as the water goes down the side to the joint. It could be sealed but better it didnt happen.

[GPW]

Using one of those utility trailers , the ones with the side walls would be one answer to this question ... no slipping off ... Removable cabin allows the trailer to be used for hauling too ...