new hybrid fomie

[bmiracle2]

So I am starting to think about the foamie that I will make this fall. I don't have a layout in mind yet, looking to make it a motorcycle hauler as well. But and just thinking about construction methods, and this is what I was thinking for the side walls. I want to incorporate some minimal wood framing to and use the foam to encapsulate the wood for strength. Was thinking of using 1x2 or 1x3's for the framing and notch out the 2" foam to fit into the framing like:


I was also thinking that using this method I could get by with just one application of fiberglass epoxy and maybe additional small strips on the seams instead of using two applications like most use on the walls to save a little money on glassing the outside. Any input is welcomed!!

[KCStudly]

Not sure I understand the concept, but off the cuff that looks like a lot of work with little added benefit.

The wood has a lot of strength by itself, as would the foam if coated with epoxy/glass layup. So I don't see the point of putting the wood in the middle. The strength is in the outer fibers (in this case the glass).

If you are thinking that the wood is needed in order to screw things to, I don't see that as being very stable what with the foam in the middle being able to crush and lacking side stability on the fastener.

By all means, do plan and do build, and if I have misunderstood your concept please do explain further.

[TJinPgh]

Well, I can kind of see the point if you were looking at it the same as adding rebar to poured concrete.

In this case, though, the strength of the foam (that's not skinned) comes from it's thickness. By notching it I suspect that you've greatly weakened it by creating a half inch piece of foam instead of a 2" piece.

Additionally, for the same reason why rounded doors and windows are considered better than square ones, you end up creating a stress point at the corner of the notch.

I'm not sure that glassing it will compensate for that or not. Certainly not any more than just glassing it by itself.

But, I'm just learning about these things myself so it's entirely possible that I'm wrong so hopefully somebody will correct me if I am.

[GPW]

TJ, what we found is Simple is better and works very well ...

[bonnie]

Was thinking of using 1x2 or 1x3's for the framing and notch out the 2" foam to fit into the framing like:

I find this interesting. Would you be doing this around the windows and doors? Sort of like a -- someone correct me if I'm wrong in the terminology-- rabbet cut? I see this encapsulating the wood parts with foam much like the sandwich effect for walls.

I am doing something similar with the door on my BUB. I will be mounting the wood blocking for the hinges into a foam sandwich. It will give me support and strength, I hope. Looks good in my head anyway.

Welcome to the foamie world. Look around there's a lot of great know how here at TTT.

[bmiracle2]

I was thinking about doing this so I could hang things from the walls being able to screw things into the walls and to make window and door fitting easier. I did not think it would make it weaker. I was also going to use glue in the rabbit joint as well. I was going to use the foam as panels that fitted in-between the wood frame having the rabbit joint on all four sides of the foam.

[TJinPgh]

Well, you are ultimately asking a couple of the questions I was wondering about myself. Like, if you do a wall entirely made of foam how do/can you hang anything from it, like a cabinet or shelf.

Plus things like framing around windows and doors and such.

Given the way you've drawn that I would think it would be better to simply build the 1x2 or 2x2 wood frame and then fill in the open areas with the foam. Then skin/glass it however you wanted.

[bonnie]

Others will chime in, but a lot of people are adding wood blocking for hanging and such. The idea of skinning with foam panels instead of wood or frp or whatever, is an interesting idea to me. Could be best of both worlds. You'd still have to protect the foam with either canvas or fiberglass or paint.

There are as many solutions as people building.

[TJinPgh]

Dunno... I'm kinda liking the idea GPW came up with...

[GPW]

You can always put in extra wood bracing where you plan to install bigger things , or “hard points “ for the light stuff like cargo nets , lights, etc.

[KCStudly]

The trick is knowing where to put the hard points before the finished surface goes on!

[bmiracle2]

Given the way you've drawn that I would think it would be better to simply build the 1x2 or 2x2 wood frame and then fill in the open areas with the foam. Then skin/glass it however you wanted.

I am already thinking to have a 1x2 frame, but Doing the rabbit joint in my mind would have a some of advantages; one being that it would be easier to store the walls before you glass( it all stays together); two being that you have only one joint to fill( and was thinking that it would be easier to make a foam-to foam joint smooth then a foam to wood joint); three, wood be completely sealed( no mold, or lots of mold if water did get in); four, foam would not move while glassing since I'm thinking about glueing the joints too.

I know its more work than may seems necessary, but I have never had that good of before hand planning on any of my projects so the framing would give me some redesign options if it came to that

GPW's design is pretty cool( never saw this in the forum), but how would the outside foam skin attach? ....Glue/adhesive ?

Feel free to poke holes in my logic.... as I'm not really speaking from any experience and appreciate any constructive input

[bmiracle2]

If you are thinking that the wood is needed in order to screw things to, I don't see that as being very stable what with the foam in the middle being able to crush and lacking side stability on the fastener.

Well what i was thinking is that I could have small shelves( not caring too much weight, but still convenient) and that anything that I would mount would have a backing plate spreading the weight over a larger area. Do you think it would still crush it the foam? And too the drawing above was just to understand construction method I was thinking about, still thinking on the design.

[TJinPgh]

GPW posted that pic in the Low Wider thread of this Foamie section.

He can chime in on how it works but, it's basically a double layer wall. A 1x2 flat frame (which is actually 3/4" thick) with 3/4" foam in the open areas. Skinned on the outside with a whole sheet of 3/4" foam.

I'm guessing it's glued on with either Gorilla Glue or Titebond II.

That might have some of the same advantages of your design, without any of the weak points. Although, it probably would cost slightly more to do.

[GPW]

The idea of using the 1X2 framing was actually Steve’s (linuxman) idea , which is very practical when you can’t find thicker foam (everybody seems to stock the 3/4” foam )... The idea was to fit the framing thickness to the thickness of the foam , then the outer layer is glued over all that ( for more insulation and a uniform surface ) and all that covered with canvas... or glass should you choose that route ...

Like KC said , it helps to have a Plan on where you’re going to locate everything , so attachment points can be attached before the finish skin goes on ... You could do a dowel and plate style hard point for lighter things (after the fact) , but for shelves, bed frames, etc , you might need More bracing and that should be considered prior to the build ...

The current thinking for my new build is to use sliced sheets of 3.5” thick beadboard , which BTW fits standard 1X4 ( 3/4” X 3 1/2” ) lumber... again making building easy, just simple cross cutting of standard lumber , no custom woodwork , which requires more advanced tools , ..