What are the best materials for supporting a foam based layout.

[mionerr]

Maybe I'm an old geezer. I follow some of the other Roger's guidelines, specifically:
1. I like a flat, zero grade surface.
2. I like to be able to revise the track plan with no change in the base material or bench work.
3. I enjoy detail scenery work and building kits or scratch building.
4. I build for portability
The only thing I don’t follow is the detail scenery work.  Ick. Not a detail guy. I am, however, into operations and am part of a large group of operators.
I’ve built two dozen Ntrak modules, several of which are still in use in various states I’ve lived. I’ve also built 8 oNetrak modules. Since my company has moved me often, I’ve built at least bench work for 10 home layouts.
All that said, the current layout is the largest by far at 18’ by 36’. Since I’m modeling the San Joaquin Valley in California (really, really flat), I decided on dominos. Most are 2’ by 8’, 1/2" plywood on a frame made from 1x4s. This is topped with (gasp) homasote. This layout is moveable as opposed to portable. The plan when I retire in a couple of years is to move a bit closer to grandkids. But that will be less than 100 miles. I can get the sections out of the basement; after all, I got them down there. A requirement for the next house is a basement. It’s hard to find a house here in Colorado WITHOUT a basement.
Homasote works fine here. Humidity is not an issue as it rarely gets above 20 or 25%. My basement is a constant 63 degrees plus or minus a degree or two. So the plywood homosote works for me at this time.
At 65 I’ve started thinking about my “diaper” layout. It will be 2” foam on shelf brackets in a home somewhere, maybe Dallas where humidity is more of an issue. Foam would be a better choice.
Bottom line, there are different factors driving the benchwork for different locales and different seasons of life.

FWIW,

[robert3985]

There is no need to build a layout that doubles as a tornado shelter when working with N.

You say that now, but wait until that twister starts disintegrating your house around you.  At that point, you'll wish you were at my house, with me nice and safe under my layout! 

[LV LOU]

I'm, not worried..The former owners of my house were thoughtful enough to build a 10X15 coal bin in the front of the house with 18" thick concrete on all four sides,and an 1-1/2 thick oak door with triple steel hinges,LOL!! Even the outside door is steel..I figure I'm ready for a close nuke..

[OldEastRR]

Asking "How should I support my foam-surface layout?" is an incomplete inquiry. Several other important factors need clarification:
1) Is this layout to be "permanent" or a portable module subject to frequent handling and transport?
2) Is this layout to be used by careful operators with a light touch, or with casual, heavy-handed ones? If the layout is to have visitors, which of these two types would they be?
3) Is this layout a "flat pool-table surface" type, or does it have various heights ranging from below track level (and how deep) to above (and how high)?
4) Is this layout in a protected environment, or one of less-than-optimal conditions? And if so, what are those variables?
5) What is the minimum thickness of the foam sheet to be used? What is the maximum?

I've seen 4" thick extruded Styrofoam sheets that could easily be used as-is for a layout's combined benchwork/track support/finished layer -- all you need do is cut some holes for legs to make them stand stable and you'd be all set. Would this survive you falling full-length on it? No ... but even if you had a layout construction that could, what would happen to the rolling stock, track, scenery, etc where you fell?
Here's a simple criterion: if it can hold itself and all that's on it up without collapsing or sagging, it's an adequate base for your needs.

And a sectional layout need not only be sectional for transport: as I said in my original post, the capability of handy sections being removed from the layout and taken to  more convenient location to work on - for repair, new track arrangement, changed scenery -- is a better option than working while stretching out across a layout, or sweating and cramped under one.
 

[DKS]

Asking "How should I support my foam-surface layout?" is an incomplete inquiry. Several other important factors need clarification:
1) Is this layout to be "permanent" or a portable module subject to frequent handling and transport?

I build for portability.

3) Is this layout a "flat pool-table surface" type, or does it have various heights ranging from below track level (and how deep) to above (and how high)?

I like a flat, zero grade surface.

4) Is this layout in a protected environment, or one of less-than-optimal conditions? And if so, what are those variables?

The layout I am planning will be ... in a basement area large enough to have my home office in the same location as the layout.

5) What is the minimum thickness of the foam sheet to be used? What is the maximum?

I am searching for options using the 2 inch extruded polystyrene on a wooden frame. 

Roger, given that you seem to prefer sticking with what you've already been doing, more or less, then I'd recommend perhaps making life just a little easier on yourself by going lighter. That is, take advantage of the foam's rigidity, and rather than using heavy ply on a substantial frame, make a simple 4 x 8 foot box from 1 x 3s, with one cross member in the middle, top it with 3/16" luaun plywood, then bond the foam to the ply. Luaun ply is lightweight but should be more than adequate support for the foam. It's also easy to make openings in luaun--it can be cut with a utility knife. You can buy it in 4 x 4 foot pieces, which you can carry yourself and more easily negotiate into the basement.

As for legs, glue/screw 1 x 3s in an L shape, and bolt into the corners of the box frame. The L shape is plenty rigid but much lighter than 2-bys. Some 1 x 2 bracing should finish the job, and you'll have a sturdy structure that can be easily lifted and moved.

[spookshow]

Being pretty lazy (not to mention unskilled when it comes to woodworking), I just used cheap Office Max folding-leg tables for my "benchwork". No complaints so far.



Cheers,
-Mark

[rogergperkins]

Mark, I found similar legs at Home Depot which could be an even less expensive approach.

The idea of building 4'x8' boxes with cross supports sounds like the approach I will take.
Comments I have read about using plywood cut in 3" wide strips versus dimensional lumber also sounds interesting.
It is not clear to me if 1/2" plywood is okay or if 3/4" would be a better option.
 
Looks as if this had kept the nitpickers entertained.   

[robert3985]

I'm not big on the "box" philosophy of supportive benchwork.  This is called "butt joint framework" and has several disadvantages as compared to "L-Girder Framework" which are well iterated in Linn Wescott's Kalmbach book "How to Build Model Railroad Benchwork".

Particularly for you, "L-girder benchwork" or "Lattice framework" provides a space between the L-girders to attach your folding legs, so they'll fold up between the vertical parts and be out of the way. That's what I do on mine.

To make it short, here's an illustration I borrowed from Linn's book that graphically illustrates one version of "Lattice framework" for permanent layouts.  A nice touch would be using the ends of the joists to attach your fascia to.  Anytime I can get a benchwork component to perform double or triple duty I like to think that lessens complexity and saves a little weight.  I would also use something lower than Linn's illustrated joists, like 2X2 redwood balusters (light, straight and stiff), or just glue your extruded polystyrene sheet directly to the horizontal tops of the L-girders...and don't put 'em on the edges of your sheet.  Position them in about a foot from the edge if your top is 4' wide.  You don't want your legs to be right on the edge of the layout, but extend downward from a recessed position, and a 24" span between the legs is plenty sufficient to be stable. 

Linn Wescott's Version of L-Girder Benchwork:

[DKS]

All hail, Linn Wescott. God of benchwork. May his L-girders live on beyond the end of time... 

(In truth, I do not mock him; but I do think there really are viable alternatives, despite what hardcore believers maintain...)

To make it short...

Cough, cough...

[robert3985]

All hail, Linn Wescott. God of benchwork. May his L-girders live on beyond the end of time... 

(In truth, I do not mock him; but I do think there really are viable alternatives, despite what hardcore believers maintain...)

Hahahaha...   Yeah, I've got the 3rd printing of the book dated 1983...hmmm...30 years ago???  Wow...doesn't seem that long!  Some of the hardware suggested is way out of date and truthfully, either butt joint OR L-girder would work okay for Rog.  I just thought since he wants foldable legs, the L-girders would give him an easy place to mount 'em and hide 'em when they're folded up.  Plus, if he wants to make curved fascia, the joists would easily enable him to adjust them so's his fascia could have a nice, artistic curve on it.

But, you and I do agree that a supportive base would be good.  I especially like your idea to use steel studs...ugly, but light and non-warpable and only tin-snips needed to cut 'em...but I'd make L-girders   

Cough, cough...

Okay, now turn your head the other way....   

[LV LOU]

Linn Wescott's Version of L-Girder Benchwork:

That benchwork makes no sense to me at all,Linn Wescott non withstanding..Why would one essentially build a nice,stable box shape,then stand wood up on top of it on edge,and put a piece of flat whatever on top of them,with no support on the sides? It may fill some "need" he felt at the time,but as for a construction technique,very poor..

[conrail98]

That benchwork makes no sense to me at all,Linn Wescott non withstanding..Why would one essentially build a nice,stable box shape,then stand wood up on top of it on edge,and put a piece of flat whatever on top of them,with no support on the sides? It may fill some "need" he felt at the time,but as for a construction technique,very poor..

If you put the flat surface directly on top of the L-girder how would one then do things like underpasses or rivers, etc.? L-girder is by far the strongest technique used. It is used in woodworking plans, particularly for legs, because of the stability and strength it provides in very minimal effort,

Phil

[wazzou]

Back in the day when you gained elevation with the use of cleats and risers, the joists were the attachment points.

[Denver Road Doug]

Back in the day when you gained elevation with the use of cleats and risers, the joists were the attachment points.

Yes, while the diagram shows a flat top, in reality the beauty of the system is in the joists being mount points for risers that allow for changes in elevation using a variety of methods, most commonly "cookie cutter" subroadbed.

I am learning about the greatness of foam, and I expect that my next layout will be something along the lines of that "gatorbox" but maybe using 3/4" or 1" styrofoam.   (or 2" with cavities cut out, as I'm doing now)  The lightweight steel or tubular aluminum framework might also be employed.  I'm as guilty as the next overengineer with the overkill benchwork, but my current layout is *only* foam, (sitting on bookshelves) and it is plenty strong for n-scale.   The violitile nature of wood in areas of extreme temps and humidy is really the tipping point in it all.

[LV LOU]

If you put the flat surface directly on top of the L-girder how would one then do things like underpasses or rivers, etc.? L-girder is by far the strongest technique used. It is used in woodworking plans, particularly for legs, because of the stability and strength it provides in very minimal effort,

Phil

Simple..You start the flat surface with 2" foam,and work up from there..