Plywood on Foam with no Cork ?


I have nearly completed my "practice layout" , a simple 6x1 "test layout" to see if I had the patience and enjoyment for the hobby. I'm addicted !
Finally at my old age (45) I have both time and money ... a rare window of opportunity that may slip from me any day ... :) But mostly I've discovered I like building more then running ... I did a full hand-laid track setup including hand laid switches ... god I love that !

Well with the "practice layout" mostly done I've got the "wifely buyin" to take over 1/2 my basement to do a REAL layout ... I need to change into my brown pants I'm so excited ... So I'm looking (well DREWLING) at about 300" x 200" to do with what I want. and honestly I want it to take a long time.

My "practice layout" I put together with a frame of 1x3s' with 1/2" plywood top. On top of that I used standard cork bevled roadbed and hand laid the track/switches. It worked prety well. But looking at a bigger layout I want some *depth* ... so I'm looking at an 'empty' type frame so I can get vertical action ... I'm playing with extruded foam and love it. Cheep and plyable and has the ability to do 3D layouts.. So many options ! What do people do ?
Considering I want 100% hand laid track (spikes) I know I need some kind of solid roadbed. The guys at seem to do this with a thin plywood OVER foam. I've also seen foam over plywood then cork over the foam. I dont think my spkikes are long enough to make it through the ties AND the cork ... so I suspect I could do cork over foam, or Plywood over foam or Cork over plywood over foam. OR ... plywood over frame covered by cork and just foam around to do the 'hills and stuff'.

I know this is really vague and there are a lot of oppinions and nothing is "right" but I'd love any suggestions. I'm really excited about starting a project I hope will take a few years at minimum and want to plan it out right ... I learned a lot from my practice layout enough to know I'll love doing this but ... not sure which way to go.

Ideas ? Contra-Ideas (what NOT to do ?) ? thanks all !
Switch to spline roadbed for the open frame part, and once it is installed, use aluminum window screen (the anti-insect stuff) cut to fit and use a hot glue gun to glue the one edge to the spline roadbed and the other end to the frame. Use crumpled newspaper stuffed into grocery bags, tied off at the handles, and stuff them in good and solid behind the screening...below it...for support. Use wood lath as a scaffold below the bags to keep them in place, and pull it all out once your terraform is in place.

Over the window screen, you can use any concoction that will look like earth and that will take stain, glue, and ground foam.

I use a mix of Portland Cement, plaster of Paris, and fine vermiculite with some masonry dye powder added to give it all an earthen tone.

I went away from foam after my first layout. I enjoyed the experience, but I found it to be largely wasteful of much of what had to be carved away to get mountains or rolling hills. There is little waste with spline and aluminum screen under ground goop.

Many, many discussions about just this sort of stuff on this forum and elsewhere. If you do some forum searching, I'm sure you'll come up with more than you care to read.

Anyway, the foam versus plywood versus Homasote versus some kind of "sandwich" or laminate is a "religious argument" IMO.

Just to throw a twist into it, I am probably going to try ceiling tile on a hollow core door next time around.
This latest link, above, is the one I used as a guide four years ago. Instead of 'masonite', I used 1/4" thick MDF. It comes in 4X8 sheets, just like plywood, and you can rip it at 15/16" to get many 8' long lengths which you can laminate 5 or 6 ply, as you need. A narrow gauge HO layout would only want 5 ply, maybe even four.

The huge advantage of spline roadbed is that it naturally forms vertical transition curves into/out of a grade, and it also provides excellent and natural easements into curves. If you are planning fairly tight curves, easements become that much more important, and the splines will guide you through them.

A third advantage, once you figure out how to do it, is that spline roadbed can have super-elevated curves. You make them level on the uprights, or risers as we call the individual pylon supports, but before you lay track, or maybe before you make the scenery, you move the bottom edge of the riser outward an eight of an inch or so, maybe 1/4", so that the arc it creates when you rotate the bottom edge toward the outside of the curve, it also rotates the spline roadbed attached to it at the top. Now you have your super-elevation!

Thanks for all the info ! Ok one last question. How do you cut the plywood/MDF in clean even strips ? Lots of talk about "ripping" but I am guessing the only decent way is with a table saw ? I doubt my hand circular saw would do a good job. I'm going to be borrowing a Miter (overhead circular) saw for the project but trying to avoid investing in expensive tools I'll never use again ...

Which is why I'm still "inclined" to the cookiecutter plywood roadbed as I can use my jig saw for that.
I Just used a circular saw. It will be straight enough. If it isn't straight enough for you, simply put the uneven side towards the center. The seams will be covered with foam or plaster cloth anyhow.

Several discussions about "wastage" using plywood cookie-cutter vs laminate/splines. I dont quite see that.
I can understand when you cut curves out of plywood you end up with a lot of scrap. (although creative layouts may reduce this). But compared to a Laminate approach, looking at the drawings it appears to me that you'd use about 2x-4x as much wood for a laminate because they are stacked vertically then you'd use with plywood horizontally. Surely that more then makes up for the "wastage" ? Worse case ... suppose I had 8 feet of straight track. Using a 2 inch wide roadbed.
Using plywood I'd use 8ftx2in of wood = 192 sq/in. Using a laminate say of 1/2 inch something. 1 inch "tall, and 4 layers to give me 2 inch roadbed I'd use 8ftx4inx1in = 384 sq/in of wood. Or If I used 1/4 inch something with 8 layers = 768 sq/in.
So thats a 2x to 4x increase in sq/in wood used to do laminate. Thats worse case of course.
But it seems to me even with curved track that the "wastage" argument is not valid except maybe in extreme cases where you'd cut out one big curve on a 4x8 plywood and toss the rest ... but surely you could do better then that (cut smaller sections and stack them inside each other.)

I'm beginning to see why this is a "religious" argument :)
I think I might try cutting some strips off my plywood and seeing how they look in splines ... good thoughts all !
...Lots of talk about "ripping" but I am guessing the only decent way is with a table saw ? I doubt my hand circular saw would do a good job...
Which is why I'm still "inclined" to the cookiecutter plywood roadbed as I can use my jig saw for that.

I had the place that sold me the single sheet of MDF do the ripping, and yes, two fellas ripped it on a table saw with a fence. I got enough spline lengths to do over 50' of main track plus two spurs, one a switchback.

I paid $10 to have the sheet of MDF cut for me.