Maybe I should just go back

I looked into foam but after realizing that I'd have to use adhesives and the implications, I've stuck with what works for me, which is either plywood, OSB, or Homasote for subroadbed and Atlas track nails or ME spikes to instantly secure track - no waiting for adhesives to set and easy to pull nails or spikes if I need to relay track or revise a configuration, which I've had to do umpteen times.  I like nails and spikes because there is enough wiggle room that if the track isn't perfectly straight or smooth curves, I can tweak it to make it perfect.  I'm picky about smooth flowing track.  I don't see how you can tweak track that has been glued down without having to slice it back up and risk damaging it. 

guess I am old school and

guess I am old school and prefer the plywood/Spine methods of creating roadbed. The pink/blue stuff is great for landforms, but unless I was building a railroad similar to the Maumee Route then I would not use it.

XPS is enough strong (load?)

XPS is enough strong (load?) and stable.It is more workable than anything else and therefor  “We don't make mistakes, just happy little accidents.” as Bob Ross.
What will be the support structure? Modular? 
I will build mine layout frame from drywall studs and xps 50mm. max span about 60cm. For the trackbed i'll use recycled rubber panel :
https://www.gumex-en.eu/elaston-eltec-fs-700-elastic-damping-boards-50297.html#tab=popis-vyrobku
/>
The net is full of info about xps as roadbed.

Using foam for model railroads.

I've used pink foam for my last two model railroads and it has it's advantages and disadvantages.  It is really easy and fun for terraforming.  You glue down the roadbed and track and then cut away everything that you want below the track.  You stack the foam in layers to create everything above the track.  Works well and is a lot of fun.  When proper scenery is done over the foam it looks very realistic. It cuts with a foam cutting wire, a serrated knife or a saw blade.  The problem with it is that it isn't perfectly even.  There are thinner and thicker areas that are barely perceptable but can effect the track.  What was supposed to be flat has a dip in it so your rolling stock won't stay where you spot it, if the wheels are free wheeling.  My layout was built to be taken apart, moved and reassembled (a really good idea by the way).  When mine was reassembled the track no longer lined up across the joints.   I have not decided yet whether I am going the foam route again for my next railroad.  

plywood preferable

Plywood is preferable, certainly for framing.  MDO is Medium Density Overlay, a good grade of plywood.

a blog entry of what  not  to do with foam : https://forum.mrhmag.com/post/modules-in-storage-for-two-years-now-warped-12210212

2" foam is light and it can be used for roadbed, but must have sturdy framing.

an example of using a combination of plywood for roadbed and foam for scenery surfaces: 

http://www.nwvrailroad.org/Layout/Modular-Layout/modular-layout.html

https://forum.mrhmag.com/post/modules-in-storage-for-two-years-now-warped-12210212

Joe Fugate had a Reverse Running column in the September 2016 issue denigrating foam as roadbed !

http://mrhpub.com/2016-09-sep/online/html5/index.html?page=284&noflash

BIg fan of steel stud benchwork with 2" Foam board

Reprinting what I wrote in this thread and adding some pictures, and edits in bold.  I didn't agree with the "Reverse Running Column" criticisms 21 months ago, and I still do not agree with it. 

http://mrhpub.com/2016-09-sep/online/html5/index.html?page=284&noflash

I've had track down fo four years now on my foam board sub-roadbed on my extension, and absolutely no issues.  Granted, my benchwork is way different from the norm as I am using steel studs, with 2" light purple Owens Corning foam purchased from the local Home Despot.  So, whatever I put on top of the steel studs has a flat surface that is way better than anything I could do with dimensional lumber.

Pictures of the steel stud benchwork.

Construction consists of:

• 2x4 steel studs secured to a 2x4 steel stud wall.  Angled brackets on one side only of the stud, and there is layout on both sides of the stud wall. 
• The studs are at 24" intervals.  The foam is glued to the studs with Loc-Tite "Powergrab" adhesive. 
• 1/4" cork roadbed is glued, with the same Powergrab, over the 2" foam.  I cut a sub-roadbed coutour into the foam so that I can model the cinder sub-roadbed.  Refer to Bill Darnaby's articles which started in 1994 in "Model Railroader".
• Peco Code 83 track is glued down to the cork with the same Powergrab adhesive.  Walthers code 83 switches are spiked to the cork roadbed, not glued.
• I leave slight expansion gaps every two sections of 3' sectional track for expansion of the rails. 

"A few observations:

• I agree that the foam thickness is inconsistent. I don't lay my own  track, I have a friend helping with construction who for some reason LOVES to lay track, and he is fussy as heck.  The cork gets shimmed to overcome any variation in foam thickness.  Once the cork is shimmed, and glued in place, he sands and shims if required to get the top of the cork flat.
• In the four years that I have been running the railroad, we have seen ZERO shrinkage or expansion in the track. 
• I know I am getting my railroad built about 50% faster than traditional layout methods.  
• The foam scenery has been very easy to work with, and I far prefer it to working with hydrocal and reinforced paper towels.  I do put a layer of sculptamold over the hilly areas.  
• I have only seen slight shrinkage in the 1/2" thick foam that I use for backdrops.  I still prefer this material to the 1/4" masonite that I used on the old part of the layout.  This is the ONLY shrinkage I have seen, none on the track portion sitting on 2" foam. 
• Yes, the foam roadbed is noisy, but I have found (and confirmed with a DB meter) that once I lay ballast, and glue it down with "Matte Matte" (similar to Matte Medium) that I buy at Michaels or Hobby Lobby, the sound drops dramatically.  Maybe not as much as a traditional homasote over plywood construction, but close.  I've also confirmed that the "Matte Matte" used on the older section of the layout quiets down the roadbed also.  It drys "spongy".  Noise is the ONLY negative I see with the use of 2" foam. 
• The "mess" associated with foam is far less than I ever experienced when I built my original part of my layout out of dimensional lumber "L" girders, 3/4" plywood, and 1/2" homasote roadbed.  I use box knives, the Woodland Scenics wire foam cutter, a "Tippy", and a Woodland Scenics knife (this thing is a real blunt-force trauma tool that I only use sparingly, and it does create a lot of fumes), Now that I'm  doing scenery, I also use a bread knife.  Nice for sculpting hills.  I will never, ever again use homasote for anything.  Messiest stuff I've ever used. 
• I don't know why, but it seems like all I have to do is look at a piece of wood, and I end up with a sliver.  Even with my steel stud benchwork, I've suffered a whole lot less blood loss events that I did on my original layout.
• My basement pretty much stays in a temperature zone between 63-68 degrees F.  Humidity is typical Chicago levels.  I do NOT run a humidifier (too darn cheap, and the basement is too big).  We do run our air conditioning almost all summer, and enjoy the humidity reduction .  I have since started running a humidifier in close proximity to my sump.  

My tracklaying friend is part of Bill Darnaby's regular operating crew, as are a lot of my round robin group.  Bill's layout has now been in operation for 23 years, and Bill has run hundreds of sessions to date.  His layout has stood the test of time.  

As with any construction, there is no single "right" method.  In my environment, with my construction techniques, it seems to be working out well.   If I was trying to build in an out building, without temperature (and humidity control), I'd be looking at alternative methods.  I REALLY like the benchwork I saw on the LDSIG tour in Portland in 2015 using plywood for just about everything.

We shall see if my layout construction methods stand the test of time too.  

Regards,

Jerry

Considering Using Foam

I keep going "back and forth" on using 1-inch insulation foam on my layout.  The foam would sit on a 1/4 MDF base. 

One concern that keeps playing in my mind is the glued cork roadbed coming lose over time.  Never had this issue when gluing cork roadbed to wood but foam is a different animal. 

"Anyone had experience with how well foam holds up over time?"

Joe

    One concern that keeps

Based on my experience with cork glued with Loctite "Powergrab" to foam, it isn;t going anywhere. Can't comment on other adhesives since I have not used them.  

Regards,

Jerry

"How well does foam hold up

   Foam is better suited to a thick base with stacked layers of foam creating a solid shaped roadbed instead of a thin  riser supported roadbed such as is commonly used with plywood or splines. You can buy pre-shaped grade sections (not sure if they come in 2.5% though). I've built foam surfboards and boats in the past but wouldn't consider foam for the structural part of my layout, mainly because it's simpler to cut and support a grade with wood. I do use foam for scenery if the hills and valleys are not too severe. For a large mountainous area I'd just use hardshell instead of layers of foam.For clean up wood dust is a lot easier as the foam particles tend to get static  and stick to everything. ...DaveB

PINK FOAM

I am using 1" foam over OSB over a wood framework. Not a single problem. the foam does not absorb moisture so it is very stable. air conditioning in summer only and temperatures reached 11 degrees in my train room one winter... a separate building from the house. I glue the track with elmers school glue which is water soluble for when I redo track and it drys clear. I am redoing a large area of track now, a flat putty knife under the track and it pops off. No damage to the foam either. For long runs I cut it on a table saw, and for curves I mark the curves and jig saw the pieces out of a 4 X 8 sheet of foam. Cuts like butter. Leftover foam become mountains.

Track Alignment

I have an O scale exhibition layout that was built using 2" pink foam over a ladder frame of 1x2 pine lumber.  I use baseboard alignment dowels from DCC Concepts (other companies make similiar products).  Ever since I installed them, I have not had any problems with track alignment over the joints.

Thanks,
Damin.

Only ever used D4S pine and

Only ever used D4S pine and plywood for layout construction. And foam for scenery. It works for me and I'm comfortable using it.

Phil

Sound Plan

Pruitt, your plan is sound and will work very well, as others here have noted.  I won't repeat all they said but will add a little.  

My whole layout is 1" rigid foam board subroadbed.  I build traditional L-Girder benchwork from dimensional lumber and plywood.  I then use Foam chunks for risers, and glue them to the benchwork and the subroadbed with hot glue.  It's quick, easy, and VERY easy to modify.  I've gone back to make changes, and simply cut through the risers with a knife.  Then I can quickly raise or lower elevations.  

I glue down roadbed and track with full strength white glue.  Never any problems with track coming loose.  On the contrary, I have to soak it for a while, like a half an hour, to loosen the glue enough to remove it.  But then it cleans up great and can be reused.

For your questions specifically:

• Cookie cutter - yes, this works great!  Makes very gradual transitions.  I have grades up to 4%.
• Risers - use hot glue
• Splices - yes, same method.  Use splices just like with plywood.  Glue with hot glue.
• No issues with breakage over time.  Foam is very stable.
• Cutting - I use a snap-off blade for all my cutting.  I use a thick one for big cuts, and a small one for finer cuts and curves.  A Stanley Surform tool is great for smoothing and shaping.

Two other things.  I like the green foam from Lowes for subroadbed.  It seems a little denser, and will not be as obvious if something gets damaged and shows through scenery.  But pink and blue work fine.  I have a mix.

I've noticed lately that my foam sheets from the big box store have a curve on the ends.  I have to chop that off or I have dips where the roadbed sections meet that I have to fill with putty or plaster.  I think this is because of the poor way they store the sheets on end leaning over.  But this is only a minor annoyance.  I use the cut ends for scenery and risers.

Have fun!!

​ Thanks everyone for the

​

Thanks everyone for the great input! Tremendous help!!

Jerry, your benchwork is some of the most impressive I've seen! The detail you provided in your observations is invaluable. Thanks for taking the time to write up such a detailed response.

Michael A., I really like the direct answers you provided to my questions. They are very helpful.

Chris, Thanks for the references. Very useful.

I'll go with the foam on the first sections, which will be the Casper yard area. It's a large flat area except for a track that begins climbing in the background, so lends itself well to flat sheet modeling anyway, in plywood or foam. As I start out of the yard is when the cookie-cutter subroadbed will really come into play, and that will be at least a few months down the road, as I plan to finish scenic at least some of Casper before the main line heads out into the "wild."

My basic construction approach at this point is: conventional L-Girder benchwork with dimensional lumber; oak plywood cut into 3" strips grid on top of the L-girder (varying shaped grids, depending on the benchwork outlines; then 1-1/2" foam on top of the grids for subroadbed.

I'll let you know how it goes!

Post Pics!

Terrific!  I can't wait to see what you build.  Please post pics as you go.

If you want to read more about foam building, and see pics of the foam helix I built, there's a lot on my blog, especially on the first couple of pages.  http://model-railroad-hobbyist.com/node/24931

"My basic construction

  I'm not understanding what you are trying to accomplish with the foam roadbed? If you have the skills and tools to make wooden benchwork why not just add plywood or spline sub-roadbed and be done with it?  The wooden sub bed can be thinner, stronger, easier to grade ,and hold screws for switch machines or hold nails or spikes where foam needs special treatment for screws or glue must be used. Wooden sub-roadbed doesn't preclude the use of foam for no-structural scenic components...DaveB 

Foam Works For Me

I only have one of my modules up and building a second but I found foam was fast to cut and transfer the track plan to.  I used Loc-tite foam adhesive to lay the cork down and nothing has moved.  The module have up needed reinforcement in the way of 1/8" plywood fascia on both sides where it spans the 5' entryway but I have found it to be very strong.  Starting out I didn't know there are two densities so get the more dense one which is what the rest of my modules will be made of.

Caution with using foam as roadbed

Pay heed to this advice:

I went to Home Depot and Lowe’s and measured some foam sheets with calipers. The edge-to-edge thickness varied by up to 1/8” or slightly more. If you look carefully down a sheet sighting from the edge, you can see variations in the surface — it’s not totally flat.

The manufacturers own specs say the manufacturing tolerances for foam sheet are lax (Owens-Corning and Dow) ... sheet dimensions can vary +/- 1/8 ... which means edge-to-edge variance can approach 1/4”. Keep in mind the stuff is made as inside-the-walls insulation so lax dimensional tolerances are not a problem.

Compare that to plywood, which has a manufacturing tolerance of +/- 1/32”. Foam is fine for scenery, but I would NEVER use it under track.

Since you are going to start with foam...........

Hi Mark:

Here is the first of three construction segments that I think you may be interested in.

These are photos of a flat area that I had to apply a gradient to from the flat.  I utilized the Woodland Scenics foam grade kit, and since they did not offer one in the gradient I needed (I wanted a flatter grade), I just started hacking it up until I got what I wanted.  Glued the 1/4" cork on top of that, filled in the surrounding with foam board as required, put on the fascia, and then started filling in the area in between with good old cheap play sand as required. I keep coarse and fine play sand available, and I use it to maximum advantage to save the expensive ballast cover for the most minimum of layer possible.

 This deck bridge got inserted into the scene after we had the cork in place, the track laid, and had a stable foundation. 

Here are the implements of construction used, with lots of 2", 1", and 1/2" thick foam (offal from the benchwork, and backdrop construction) used to start filling in the scene.

I use cast hydrocal rocks.  I tried making resin rocks per Joel Bragdon's methods for an O scale module I built, found I liked working with hydrocal rocks better.   In this view, you can see how I started filling in the foam around the Woodland Scenics grade kit.  I did not start pouring liberal amounts of sand into every crevice yet. 

Here are two pics showing the construction towards the end of the scene.  I use 1/4" MDF for fascia.  The painted fascia was still wet when I snapped the second picture.  I LIKE black fascia. 

Notice the convenient workbench right below the upper level.    Separate work area for modules, we don't need no stinkin' "isolated dirty work area".     Just work top down.  Do ya think I had a plan?  You betcha.  

To close this segment is a pic from 1952 of train #100 crossing the creek. 

Regards,

Jerry

Foam

I used foam for my railroad.

Started with a 1/2" plywood frame.

Then added sheets of foam using PL300.

almost 12 years later.

No problems.

Joe Fugate wrote:Compare

Joe Fugate wrote:

Ya know, for years people who want their track level used something called "shim stock".  It is a miracle material, found in old unused Walthers switch box containers, in packages of Plastruct flat plastic stock, or, if you really want to be fussy on the height, steel shim stock which comes in rolls, and is available in plenty of precise thicknesses.  Used it for years on the day job. 

Funny, all this fuss about plywood being better toleranced, and then people put things like homasote on top of it, which also requires shimming (not to mention all the other things I hate about homasote, especially the mess).    Mate up Peco or Atlas sectional track with Walthers (Shinohara) switches, and you are shimming all the time regardles of sub-roadbed and roadbed (Peco was just coming out with their line of NA prototype switches when I did my large Walthers purchase).  And by the way, cork sands up pretty well, as does the foam.  My friend, who is my track gang, has this thing about perfectly aligned track, makes frequent use of a level, 6" straight edge, and when something longer is required, "T" track from suspended ceilings which gives a good rough indication over a long distance as to where the problem areas are located at. 

While we are on the subject of the preciseness of plywood, there is also this itsy bitsy little problem called English vs. Metric.  When I built the old part of my railroad, it depended on where the plywood originated from as to what the thickness actually ended up at, I had to shim underneath the plates that tied the plywood sections together.  Used to have to sand the top of the plywood too, as well as sand the homasote on occasion (and gets all the mess that goes with it).  So just what is the big deal with the thickness variation of foam?

You do your readers a huge disservice in pushing your "one way fits all" philosphy.   I, and others, are having great success with foam layout construction, with the most notable being Bill Darnaby, who is going on something like 20 plus years of playing with the stuff. 

I've held 17 operating sessions (TT&TO) since July 2016, and this year am on track for about 12 sessions for the year.  I have yet to have ANY problems with track buckling and associated derailments and uncouplings on any of the foam construction areas.  Sections of my area have been running for over four years. Regardless of layout construction method, they ALL require some degree of sand / file / fit to achieve problem free track.  

Opinions

There's a difference between having a personal opinion and "pushing" an agenda.

I personally would never use foam under track and I give my reasons why. That's my personal opinion.

Meanwhile, one of our most popular features in MRH is Ken Patterson's What's Neat, which now also includes a weekly video podcast on YouTube.

Ken is a big proponent of using foam for everything, including under track. You don't see me taking Ken to task on here or in the magazine because he's a foam advocate. I'm fine with Ken doing whatever he likes to do and to let him promote his ways of doing things. Some of his approaches are something I would never do on my own layout.

At the end of the day, as the founder and editor of MRH, I have opinions too, and I do express them. I apologize if that comes across as "pushing an agenda" because that's not the intent. You can see from things like Ken Patterson's very different approaches on some things, that MRH overall isn't pushing for or against foam under track.

So saying we're pushing any "one way fits all" agenda isn't quite accurate -- but we do still have our own preferences as modelers and we won't hide those.

There is a big difference between Ken's approach..............

and yours.  Ken writes an excellent column, shows people how to do it, and doesn't bring his personal opinion into the matter.  A column chock full of information. 

You write a column intended to be confrontational.  That is fine if you want to inflate forum traffic, but it denigrates the efforts of others.  It calls into question our judgement. Given your stature as a publisher, not to mention a previously published author in another major magazine, a significant portion of your readership is going to put a whole lot more emphasis on what you have to say than the rest of us unpublished masses.  

From your Sep. 2016 article:

The OP didn't ask if plywood was a better material than foam board, he asked how to work with the foam material. 

I provided feedback on how I am working with foam.  I also listed my experiences using it for the last six years of layout construction (after the steel stud benchwork was done), and gave what I saw as the advantages and disadvantages of it.  I have a few other things I'd like to say about working with the material, including a neat way to install Tortoises and Blue Points without having to go underneath the benchwork.  For that matter, other than connecting feeder to the main bus wires with IDCs, I don't spend much time under the layout at all. No need for a "layout rotisserie". 

If you want to continue to drop your "opinion" into the thread, other than your experience, which, except for foam scenery, you have no experience with, I won't waste my time.  I have a layout to build, which is where I'm heading now.   

On the other hand, if Ken wants to offer his experience to the thread, THAT would be highly valued, as he is actually BUILDING a layout with the stuff, including using it as sub-roadbed.

Mark, if you need any further information, feel free to contact me off - list. 

Again, I apologize

Again, I apologize.

My intention is to provide a full picture of all considerations, so we think things through fully, not to be deliberately contrary just to be negative. I am not just trying to be confrontational or to belittle anyone else's efforts.

(The one column I write that is deliberately contrary is Reverse Running, but that’s often tongue-in-cheek, with a wink-wink and an image that’s over-the-top to remind everyone its about getting us to see another view with a hint of fun, not to just be a big pain in the tush.)

My heart is to be helpful, not be a pompous troublemaker. One thing I really hate about being the head guy is the excess weight my opinions seem to carry. It seems I should just keep my opinions to myself in that case.

Again, I’m sorry if I’ve upset anyone.

P.S. One final note: I have ultimate say in what Ken talks about and if I wanted to, I could expunge his examples of track on foam, but I’m not into censoring ideas that I don’t happen to agree with. The more ideas, the better. I take a very light hand when it comes to editing MRH — or even what gets discussed on the forum.