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Discussion in 'FAQs' started by eddie, Oct 7, 2006.
Can I use foam board (blue, home depot) instead of plywood as a table? Anyone try it?
You might find some valuable information in this thread.
Personally my next layout will be foam on top of plywood. Something to the following effect.
I don't think that the foam board is strong enough to support all the weight of the stuff on the layout. My guess is that it will probly crumble do to the heavy weight of everything on top of it, plus you are most likely going to be carving in it right? So that would further weakin it. I would highly suggest a plywood surface on benchwork and then the foam on top of the plywood. You wouldn't want all you trains and entire layout to fall to the ground!!
Believe it or not, the foam is tough. In my now former line of work as an commercial insulator, we've used it on exterior ductwork, with a covering of fabcloth to protect it from the elements. If supported correctly, at about every 12-16", it should be sufficient for a shelf layout. But if you laid it on 3/8 or 5/8 plywood, it would be better for a wider area, wider than 18".
I'll concur with thoroughbreed. Two inch foam is quite rigid and will require minimal support. If you add to the upper surface of your base foam by gluing additional layers on for scenery purposes, you will gain rigidity. I have even made reinforcing strips of foam mounted on edge under the bench work when digging depressions in the foam. Like everything else, foam has its limits. I wouldn't recommend trying to walk on benchwork made of foam.
I think what Trucklover was getting at is if you plan to cut into the foam, a single layer, you're going to greatly weaken it. A creek or river running across the layout will create a breaking point. Not to mention accidentily cutting all the way through
But if you use a sheet of foam, uncut, in place of plywood I think you guys are right. But who can resist cutting it once it's in place - I mean, it's foam. It's made to be cut!
I think it wold be strong, but I'd still put it over a sheet of plywood, which is actually what I plan to do with mine
Laying it on plywood is great. What I'm trying to say about the blue or pink extruded foam is its difference from white styrofoam. White styrofoam is made from pellets kinda glued together, blue or pink extruded is laid out like wood in that it actually has a grain to it which runs from top to bottom. If you score it from top to bottom, you can snap it straight, but in the same aspect you can actually cut a circle out of it and the remaining pieces retain their strength. Try doing that with white styrofoam and you've just created a snow pile.
I think it would hold the layout itself, but I would remember a few things.
1. The layout weight will grow. By the time you add track/ballast/glue/structures/groundcover/Locos and Cars, its gonna add up.
2. From time to time I find myself leaning on my layout, or reaching deep in on it to fix something. I know you would be conscious of this, but these things do add up the weight and it would only take one time leaning on it or setting something heavy on it and the whole thing goes down.
But let us know the results if you go this roughte.
Didn't you say in another thread that you are modeling in "O" scale? I know that some of those O-scale loco's are pretty heavy. The new Blackstone white metal O-scale loco's weigh in at over 6lbs. alone. Is there a weight limit to blue foam? Would such added weight require extra support?
Man, O Scale would definetly mean more weight, I would strongly suggest using a plywood base!! Just my thoughts:thumb:
Thanks for the advice! Sounds like I'll use plywood for sure.
I am using 1/4inch plywood with 1/2 inch foam on top of it. Works fine for me :thumb:
1/4" ply, Good choice, I have 3/8" ply
This reminds me how overboard I went with mine. I used 1/2 plywood with sound deadening board over it. I them framed it in 2x6s and braced in the middle with 2 more 2x6. This thing could survive a tornando.
foram board instead of plywood
Persuing this further -- if I use 1/4 ply with foam on top = how do you support it? I have 0 scale trains. I need enough strength to carry the loads.
The thinnest plywood I ever used was what I currently use which is 3/8's inch. I would have gotten 1/4 but this was on sale. ANyhow, I would not use just straight foam unless it was 4 inches thick or something like that. Just a thought, hope it helps
Yeah, I think that will probably hold! I've been influenced by my father, who built a very stout workbench using 1x4's for benchwork and legs.
PD- Nothing like a little overkill, aye? I think we all have built tanks at one time or another.
I've built shelves, benches and numerous other frame things using 1x3 economy boards, all ended up very strong and stable. If it's still wobbly add some diagonal bracing.
Honestly, for my next layout I plan on using furniture grade plywood ripped into various strips, basically making my own 1x2, 1x3, and 1x4. It's more work, but ending up with boards taht are straight, strong and not subject to twisting and warping makeing it worthwhile, as far as I'm concerned. For the money, it's worth it and it works out to be cheaper.:thumb:
Oh yeah, as for using plywoood for a foam base, I'd say yes, but what thickness it needs to be depends on what free spans are expected. Like everything in the world, it's all relative. When in doubt, go thicker.
I think you have to think about what you are going to do with the layout. If it is going to be built in place, and never to be moved, then you can't really overbuild it. If you are making a module that needs to be portable to go to shows, then weight is a big factor. As Zedob mentioned, longer spans need more strength than shorter spans. If braced every 12 inches with a 1 x 2 cross member, 1/8 inch luan door skin is very strong. If you try to use it with cross members every 24 inches, it will sag and warp between cross members. Foam is very rigid, but it is difficult to mount undertable switch machines to it. If the foam is glued to plywood, even as thin as 1/8 inch luan, then you can mount switch machines, or other undertable devices directly to it with screws. If you need 2 inches of foam to maintain rigidity then plan on using 2 or three thicknesses of 2 inch foam so that you can carve in gulleys and washes in the top 2 layers without compromising the strength of the 2 inch foam base. A couple of final thoughts on thought on foam, remember that you can't use nails or spikes to hold track on foam. If you are going to use foam, you will need to use glue to mount roadbed and track. Also foam is ver rigid, but it is not very resistant to sharp objects. That factor makes it great for planting trees, not so good for planting elbows, fingers, or even hands if you lean on it!
I noticed from your original post "Need guidance" that you are talking about a 36 inch wide layout. If it is a shelf that is only accessable from one side, you will need places to rest one hand for support while reaching across the layout to rerail equipment on the back of the layout. If you are using foam, and you lean across and try to support your self by putting down a hand to lean on, you will at least put a deep handprint into the layout. I would suggest that pieces of plywood, 1/8 inch is plenty thick if supported by foam, that are about 12 inches square will work to support your weight. You can make them function as bases for structures, or even parking lots. Make the structures removeable, then if you need access, remove the structure, and use the base to lean on. In planning your layout, you need to experiment to see what you can reach one handed and what you will need to rest on one hand to reach the rest of the way across, and plan the necessary support accordingly.