My wife (Jenevra on these boards) and I are planning our layout and we are curious on the Foam as the base over plywood. In the “Building a Model Railroad Step by Step” by David Popp he makes it sound like it’s what we should use. Are there any downsides to using Foam?
How much should we use if we decide to go that route?
Thanks!
Foam insulation board is a great product for model railroading. The only downside i know of is it can be a bit messy, lots of foam “sawdust” particles when cutting it. A shopvac is a must when using it.
The only other thing I can think of is it dents easily when you lean on it or press on it with a tool or some object. Otherwise very useful, easy to deal with product.
The key is for us to keep our cat off of it 
Yes, I have a piece that the cat kneeded, very messy, but I think that when you get it covered it should be OK. Not really hard to fix, latex caulk smoothed over it or just paint and leave it as “textured.”
A hot wire tool or hot knife ($15 Harbor Freight) will greatly reduce the mess, BE SURE TO HAVE GOOD VENTILATION.
Also, using an anti-static spray helps with the sawdust sticking to things.
I like working with it.
Have fun,
I’d suggest a hot-wire foam cutter with an extension. It cuts down on the foam particles.
A shop vac is a must.
So now that we are deciding to use FOAM, how high do I need to make it? I was thinking 6"?
Thanks!
I use 2 inches of foam and NO plywood for my HO layout. I have a simple box frame with 16-inch spacing between the support rafters. The foam is easily stiff enough to bear this load without bending. As has been mentioned, it’s not going to take the weight of an adult male of the species, particularly not one who enjoys his beer as much as I do.
I don’t have a lot of terrain below track level, so I haven’t gouged my foam too severely to make canyons and such. If I wanted that, though, I would stack from below and build up. A 6-inch bed of foam is way too much.
One thing you can’t do with foam is directly attach under-table switch machines to it. I don’t use them myself, so this isn’t a problem. Some folks glue a small piece of plywood to the bottom of the foam and attach a tortoise to that.
Here is 2" foam on my benchwork. It is more than enough. You don’t need plywood underneath if you support it well. I like the ease of shoving wire and other things through the foam and I think having to also navigate through plywood as well would have driven me Batty.[:-^] I can also climb on top of it by putting a 1’ x 2’ piece of plwood to kneel on. No dents. For hills and mountains just stack foam where needed and carve away. There is a U- tube series on using extruded foam for model railroads, you should check out. Good luck.
Brent
Perhaps what you are really asking is, “What are the alternatives to foam, and how do they compare?”
The traditional (before foam was popular) way to build a table layout was with a wood grid supporting a sheet of plywood. Possible downsides are weight and need to have/use some wood working tools. Either or both of these may not be downsides - it depends on your personal situation. For a permanent setup, weight is only a disadvantage if/when you are moving the layout. Having the tools and familiarity to work with plywood may tilt one’s preference one way or the other.
Then there was foam over a simplified wood grid (what many of the other posters have chosen). Advantages are light weight, limited need for wood working tools/skills (just enough to put grid together). Biggest downsides in my mind are the amount of work necessary to avoid flat scenery, and learning to carve foam to achieve the desired result (it’s not difficult, but is a new skill for many). Smooth transitions to grades may need more thought than with the traditional plywood cookie cutter. Because foam does not hold nails, spikes, or screws well, roadbed and/or track must be built with glued construction. Glued construction has, for the most part, become preferred over nails, spikes, and screws for mounting track regardless of whether foam or plywood is underneath.
Then there was a combined thin plywood and foam. The combination is somewhat quieter than either material by itself, and both plywood and foam can be thinner than if used by itself. Or the supporting grid can have much wider support spacing
I’ve tried the foam under the track (on top of plywood) on a movable sectional layout, and I don’t like it. When I lay down a curve, I usually need 3-5 tries to get it to flow properly. Easy to do when using nails, not so much when gluing the track down. The foam dents and moves around too much under the track, I feel.
For a non-moving home layout it might work, if you can get the track curved right to first time when you glue it down. For a portable layout something more solid is needed, probably 1/2" plywood at minimum.
I would suggest at least a quarter inch plywood under the foam. This adds strength and gives you something to screw into if needed, and over time you’ll probably need it. The foam talked about is builders insulating foam that can be found at Lowes or Home Depot. 2 inch thick is pretty common.
I also covered mine in plaster cloth before coloring the ground. This hids all seams and gives the ground a good texture to start with.
Good Luck
All great amount of help! Thanks all!
If you are in Ohio, you should have no problem finding 2-inch foam. However, if you happen to be a former Ohio Guy living in California or some other relatively warm place, you may have to look around a bit, or even special-order the stuff.
On my last Home Depot excursion, I found a couple of pieces of “damaged” foam. They gave me several dollars off each damaged sheet, just for asking.
Brent
Are you using “table top” switch machines or ground throws? If not, i.e. under table machines, how do you mount them?
Alan
Where I will be using switch machines, I will glue a piece of plywood of an appropriate size and thickness, to the underneath in the appropriate place. A trick I saw on this forum.
Another way I will visit (I also saw it here) Is to mount the switch machines all in one place near the edge of the layout and run radio control aircraft cable across to the turnouts. I use to fly R/C planes for years and know for a fact these cables move with very little effort. Maybe the originators of these ideas will chime in and refresh our memories.
I plan to use about six or eight switch machines and the rest ground throws.[C):-)]
Brent
Brent, something like this? http://www.trainboard.com/grapevine/showthread.php?t=80011
That is certainly one way to do it and would save buying switch machines. You would have to incorporate a sort of spring lock system for most turnouts into the cable assembly. That would not be difficult though.
The one system I was talking about had tortoises lined up just inside the fascia and used toggle switches. Cables ran to the turnouts. Here we have a choice of flip a toggle or pull out a knob. For those on a budget it’s a nice alternative to have. If $$$ is not a concern it’s whatever floats your boat.
By the way there is a third way to mount tortoises directly to foam and that is with industrial strength Velcro. I have seen it with sticky back or or without. The sticky backed stuff I have used did not work well over time, so I would get the non stick and use glue.
I am a real noobe at turnout control. Using cable is an interesting prospect for me though as I have lots of R/C stuff still laying around. Take care.
Brent
Thanks Brent for the replies. I haven’t decided yet on how I will handle the turnouts. Under table may not be an option (I have up to 3 inches of foam under roadbed planned) and Tortoises, while not exactly expensive, add up quickly (but then so do all the other options other than ground throws).
Alan
Eight years ago, after reading an article in MR about a foam-based layout, I rebuilt my ‘garage empire’ using the 2" Corning extruded pink foam supported by 1x4" open-grid wood bracing. I’ve never regretted it. The foam is easy to work with (though you’ve got to be careful with your elbows if you happen to lean on the surface) doesn’t expand or contract, and since all of my turnouts are hand-thrown, I have no problem with under-table switch machines–though I know that they can be installed with plywood strips for stability.
I have a fairly large (24x24’) HO scale layout with elevations ranging from 45" (at ‘0’ elevation) to around 63" elevation at the highest point, and it’s all stacked foam under the scenery. I’m very happy with it. And the more foam you stack under your grades, the stronger (and lighter weight) the layout.
So, I will certainly chime in on a ‘yes’ for foam. It might not work for everyone, but it’s worked extremely well for me. The Yuba River Sub has been up and running very well for the past eight years in a largely uninsulated California garage. And considering my VERY limited ‘carpentry’ skills, that’s saying a LOT, LOL!
Tom [:D]
Not sure where you live, but I am insulating my basement and can say that Home Depot has a product called Foamular - it’s the pink stuff - and comes in 4x8 sheets in a variety of thicknesses. Average price for me is about $12 a sheet as opposed to $16 a sheet for 1/2 inch plywood.