Foam roadbed?

[johnjpeebles]

What's the current thinking on roadbed for n-scale?

I've noticed MRR magazine (specifically David Popp) recommending plywood, then foam, then cork for roadbed.  I was originally planning on plywood + cork for my yard scenes and I'm using spline + cork on my "out of town" scenes, but now I'm wondering if I should use phone to give the option for more contour (even if it's subtle) on the yard portions of my shelf layout.  Previously, I've put handlaid track straight down on Homasote which worked well for sound insulation, etc., but I live in the UK now and you can't find Homasote here (at least, not anywhere I've looked).

The thing that worries me about foam is I really want to focus on having bullet proof track and I'm worried that any kind of bump or knock on the surface will cause things to deform.  Thoughts?

[babbo_enzo]

Sorry, I can't resist on this:
I'm wondering if I should use phone to give the option for more contour

[johnjpeebles]

Damn autocorrect!

[Philip H]

Somewhere over at MRH there's a really good thread on foam as both roadbed and subroadbed.  Dang if I can fumble finger myself to it to day however.

[johnjpeebles]

Think this might the the one?

http://model-railroad-hobbyist.com/node/9048?page=1

[Kisatchie]

I once tried Woodland Scenics foam roadbed instead of cork for a 1' test track. I found out that if you put pressure on the track, the foam compressed and the ballasting cracked. I wouldn't use foam if you paid me and you did all the ballasting. 


Hmm... the only foam I
like is on my beer...

[Philip H]

Think this might the the one?

http://model-railroad-hobbyist.com/node/9048?page=1

Thats one of them - there was also a test thread on sound deadening qualities that got into a lot of structural and stability stuff as well.

[davefoxx]

I'm a big fan of 2" foam as the subroadbed.  In fact, on my next layout, I'm considering open frame benchwork with a layer of 1/4" lauan plywood on top of the frame and 2" foam on top of that.  The lauan plywood will provide a little more rigidity (overkill) but also a place to mount switch motors.  The 2" foam allows for easy sculpting of the land forms above and below track level.  I use cork as the roadbed on top of the 2" foam.

Hope this helps,
DFF

[johnjpeebles]

Yes Dave this is what I'm considering as well - I'll have plywood underneath and then 1 inch foam and then cork roadbed. Just worried about the foam crumpling or something which may be irrational.

[davefoxx]

Yes Dave this is what I'm considering as well - I'll have plywood underneath and then 1 inch foam and then cork roadbed. Just worried about the foam crumpling or something which may be irrational.

I prefer the 2" thick foam over the 1" for two reasons: (1) as I pointed out earlier, more room for vertical scenery below the rails (this may not be a concern for you, depending on the area that you model); and (2) structural rigidity (only because I'm concerned about someone leaning on the layout).  If you use a thicker plywood than I plan to use, that should easily alleviate that concern.  Perhaps you should make up some test pieces.

I'm not sure exactly what you mean by "foam crumpling," but I have built two HCD layouts in the past twelve or thirteen years and neither have any problems with a deterioration of the foam or the lightweight spackling that I used to build my scenery.

DFF

[Ed Kapuscinski]

The thing that worries me about foam is I really want to focus on having bullet proof track and I'm worried that any kind of bump or knock on the surface will cause things to deform.  Thoughts?

Well, if you want your track to be bulletproof, I'd recommend a kevlar or steel layer in there. How much to use would depend on what size rounds you're trying to stop. Good luck with the Russian 14.5×114.

[C855B]

2" pink (Owens-Corning) foam, 20psi, over steel studs. No wood or fiber-based products, anywhere:



I've changed the construction method slightly in recent work, using 3/4" 20psi foam as a base and then laminating 2" semi-cookie-cutter over it for track. In a year's time it has proven bulletproof. The "20psi" is slightly important because it is less susceptible to dings and dents.

I'm definitely a non-fan of Homasote. Dusty, dirty, humidity-intolerant, plus it deteriorates. There are reasons it no longer meets building code as construction sheathing.

[mplsjct]

2" pink (Owens-Corning) foam, 20psi, over steel studs. No wood or fiber-based products, anywhere:



I've changed the construction method slightly in recent work, using 3/4" 20psi foam as a base and then laminating 2" semi-cookie-cutter over it for track. In a year's time it has proven bulletproof. The "20psi" is slightly important because it is less susceptible to dings and dents.

I'm definitely a non-fan of Homasote. Dusty, dirty, humidity-intolerant, plus it deteriorates. There are reasons it no longer meets building code as construction sheathing.

I agree 100%, I used cork, then foam on one of my earliest layouts, made the switch to insulated foam board and never looked back. 1 1/2 inch is my bag.

[C855B]

I have to amend my assessment - I use Midwest cork roadbed, which technically is a wood/fiber product. Wouldn't leave home without it - very stable, easy to work with, and I've loved the aroma the 50 years I've been in the hobby. I also use 1/16" bulletin board cork for yards and sidings. Slightly less stable (slight shrinkage), but hasn't been a problem yet.

[Mark W]

Yes Dave this is what I'm considering as well - I'll have plywood underneath and then 1 inch foam and then cork roadbed. Just worried about the foam crumpling or something which may be irrational.

Been using 1" foam (2" foam as necessary for planned scenery) straight over benchwork with no ply underlay for 20 years on the home layout, and the same for every module with Free-moNebraska. 
If piece of mind is more important than cost, go for the ply underlay.  If cost is an issue, you don't need it.