Foam vs plywood

[Anonymous]

Fred,

One thing that probably helps to keep my track level is I'm using short pieces of 2X4's as the risers under the plywood, all cut on a miter saw. I didn't notice any additional effort to hold the track flat, but then I weighted the plywood down while the risers were glued in place. Nothing like brute force to make it all fit properly, right?

I also established the level in the room using a water level before I built the benchwork so that everything is as flat as possible. All of my benchwork is hung off the wall, with no legs to the floor. So far, so good.

Mark in Utah

[fwright]

In response to Mark in Utah

You have several conditions working in your favor that prevent incorrect crossways leveling or superelevation on curving grades. You have an around-the-room layout which means your subroadbed for the entire grade is not from a single piece of plywood. Mine was a 4 ft x 6ft layout with 18in radius curves and 4% grades; the 1/2in ply subroadbed was cut from a single sheet of plywood.

In your case, the slight amount of necessary twist can be easily introduced (even inadvertantly) at the plywood joints. Even if the twist is not put in at the plywood joints (doesn't take much with your larger radius curves), you can plane, sand, and form the foam to get it right. I was using a paper-topped fiberboard that could not be sanded without ruining the paper spiking surface. Nevertheless, if I took a level crossways to your track centerline along a single piece of plywood subroadbed on a curving grade, I'll bet I could detect the effect I describe. It just might be minor enough in your case to not be detectable to the eye.

Plywood boatbuilding and boat architecture has always had to keep in mind that bending plywood in 2 dimensions is extremely difficult unless using very thin material. For this reason, good plywood boat design relies on conical or cylindrical shapes so that the plywood need only be bent in one dimension. By gluing up multipler layers of very thin plywood or veneers, the 2 dimensional bending restriction is overcome. But you are effectively cold-molding your own custom non-flat plywood sheets.

Ask me if I'm smart enough to learn any of this except through bitter experience! :-)

regards
Fred Wright
jack of all trades - never mastering any because I gotta take the time to learn the hard way!

[selector]

[:O] [xx(]

[loathar]

I contacted Owens Corning to see who sold 2" thick uncoated pink foam in my area. Told them I wanted a bunch of it to insulate my train building and use some for my train layout explaining how people cut it and sculpt it for mountains.They shot me back an e-mail saying "We STRONGLY advise against useing our products for this train/hobby purpose! Our products are not intended to be cut, shaped,molded or sanded.They are ment to be encapsulated in a wall or ceiling ONLY.We strongly recommend you cease this use of our products!
Did anyone ever check to see if useing this stuff was a wise idea?

[Anonymous]

Everyone has given me a lot to think on... thanks!

[twhite]

I think that both have their advantages--plywood is more solid, and foam is easier to cut and shape. My old layout was the standard plywood base with 2x4 bracing. When I planned out my new Rio Grande Yuba Sub, I'd read an article in MR about a foam-based layout, and decided to experiment. The layout in question was a simple one-level around the wall affair, and my garage layout was to be around the wall with 2 peninsulas. It's all 2" extruded foam base with 1x4 bracing, and it's a 3-level mountain layout with high peaks and steep canyons, and the foam works just fine. It's surprisingly strong for its weight, and layering it only serves to strengthen it more. My scenery is pretty much a combination of carved foam, lattice-work and plaster cloth, I run heavy trains, and I've had no trouble at all with structural stability. As to the 'versus' between plywood and foam, I'd say that it's more a matter of what your'e comfortable with, than superiority of one over the other. I know that when people see my layout, they're kind of shocked to see that the whole thing is made up of a foam base and risers. But it works for me.
Tom [:D]

[Anonymous]

QUOTE: Originally posted by fwright

Some cautions and experiences I haven't seen mentioned in this particular discussion:

The jigsaw method for plywood sub-roadbed DOES NOT work for grades on curves (unless you have very large curves and very modest grades). If you use reasoanble thickness plywood - I used 1/2 inch - you cannot bend/twist it in 2 dimensions simultaneously to follow the grade and keep the track level (or constant superelevation) across the rails. Prove it to yourself by raising one side of an oval higher than the other (use corrugated cardboard for the experiment). The only place the track will be level crossways will be at the 90 degrees of curvature point. The upper half of the curve/grade will have the outer rail raised, while the lower half will have the inner rail raised. The steeper the grade and/or the sharper the curve, the more pronounced the effect is. If the plywood is flexible enough to make the twist to keep the track level crossways all the way around the curving grade, then it is not rigid enough to be stable in flat areas. The best solution I have heard of - but quit that layout before I tried it - is some form of spline roadbed. You can still use plywood sub-roadbed on straight grades and flat areas - just not on curving grades.

Foam does not suffer this problem because you carve the grade into the foam, and can make the adjustments during the carving.

Fred Wright
jack of all trades.... you know the rest
Picture Gorge and Western Railway - none more picturesque
Tillamook Head and Bethel Railway - to Heaven and back

Fred,

I haven't experienced that probblem with my layout. I've got approximately 50' of elevated track on my around the room layout currently under constructions. I used 3/4" plywood throughout. All of my curves are flat and smooth. I DID make the horizontal to grade changes slow, making the first 18" at half grade before diving into the full grade. I intentionally used 3/4" as it would better foce the gentle vertical transitions that I wanted.

I've overlaid the 3/4" ply with 1" foam and so far so good. Put cork on top before laying the track. Have another 15' of track to lay before I'll have a continuous loop and will start running trains on the main line. I'll still have +50' to run for the local track, plus the yard and engine maintenance area.

Some people must see the problem you've described, and some don't.

Mark in Utah

[nfmisso]

Erik;

Most likely a combination of foam, plywood and spline will work best. Different approaches work better for different areas. Plan your layout, then decide on the appropriate construction technique for each part of it.

[fwright]

Some cautions and experiences I haven't seen mentioned in this particular discussion:

If you want to be able to climb on your layout, and still have light weight, use 2inch foam with 1/4 in plywood on top. This dent-proofs the foam, and makes for amazing rigidity for the weight. I built tinplate layouts with this method, and walked on the surface without damage. The plywood is just enough to hold track and accessory mounting screws. The only catch is that the grades must be formed in foam BEFORE gluing the plywood on - you cannot bend the foam/plywood sandwich a la cookie cutter method.

The jigsaw method for plywood sub-roadbed DOES NOT work for grades on curves (unless you have very large curves and very modest grades). If you use reasoanble thickness plywood - I used 1/2 inch - you cannot bend/twist it in 2 dimensions simultaneously to follow the grade and keep the track level (or constant superelevation) across the rails. Prove it to yourself by raising one side of an oval higher than the other (use corrugated cardboard for the experiment). The only place the track will be level crossways will be at the 90 degrees of curvature point. The upper half of the curve/grade will have the outer rail raised, while the lower half will have the inner rail raised. The steeper the grade and/or the sharper the curve, the more pronounced the effect is. If the plywood is flexible enough to make the twist to keep the track level crossways all the way around the curving grade, then it is not rigid enough to be stable in flat areas. The best solution I have heard of - but quit that layout before I tried it - is some form of spline roadbed. You can still use plywood sub-roadbed on straight grades and flat areas - just not on curving grades.

Foam does not suffer this problem because you carve the grade into the foam, and can make the adjustments during the carving.

Fred Wright
jack of all trades.... you know the rest
Picture Gorge and Western Railway - none more picturesque
Tillamook Head and Bethel Railway - to Heaven and back

[Anonymous]

Erik, I am just starting a around the walls two level layout in my basement. I am trying to build the layout as state of the art as current layouts go. My basic construction method is going to be on 1x4 pine open grid work with all the continous falt areas (ie yards, towns etc) on top of 1 1/2 inch foam insulation board. I currently have two by sixteen feet built and up on the legs. As of now my only recomendation is that is you go with 1 1/2 inch thick as I did that you hold your cross bracing to 12 inches on center. If you decide to go with 2 inch thick material then you could go up to sixteen inches on center spacing. The reason I chose 1 1/2 inch is because this will be a double decked layout with staging under the main area of the layout. And wanted to save the half inch trying to keep the distance I have ti climb up grade down some. That would be one of the cons versus plywodd if you double deck a layout. Anyway, my construction has more than enough strength unless someone decides they need to dance on the layout. Well, if anyone has any questions or would like to see photos let me know and I will post some.

[Anonymous]

You've got several issues to understand and work with.

1. The best sound deadening comes when you mix two different materials. Using foam by itself or wood by itself is bad for noise. Gluing foam on wood is very good. They dampen each other out. Foam by itself has poor dampening. Many people have called it a "sounding board". Backing plywood with stiffeners (2X4's) helps to dampen vibrations.

2. Structural needs. How big will your layout be? Will it need to be moved? Will you have raised track or trestles? Will you EVER need to climb on it??? A flat layout of limited depth will have less of a need for structural stiffness than a very deep layout with trestles. And elevated trackage DEMANDS a stiff layout, or you'll be crushing and pulling apart the elevated trackwork as the layout buckles and bows. What'll make it buckle and bow? Shifting foundation / legs and the weight of scenery.

Personally, I'd steer clear of anything that couldn't handle at least a kid from climbing on it. I'm building a new layout and I've had to climb on it several times.

My suggestions:

Overkill the benchwork. Build it TOUGH. Build it to not move. Buld it perfectly flat and strong. Will it cost extra? Yep. Worth it? Yep.

Look at it this way, just how much do you plan on spending on track, turnouts, controls, and scenery? How would you feel if it went south because you cut corners some place?

Am I saying that an all-foam layout is bad? Not necessarily. If I was building a shelf switching layout, that was fairly shallow and had zero chance that young kids could get to it, it'd be fine. For me it'd be terrible, as I've got kids that'll get to it, plus grandkids in 10 or 15 years.

My layout is 3/4" plywood over a 2X4 frame, overlaid with 1" foam. All elevated track is cookie-cutter 3/4" plywood. The 3/4" not only gives strength, but forces all vertical curves to be smooth and gentle.

Mark in Utah

[Anonymous]

Im building a 'module' style layout right now (living in an apartment doesn't give me much room for HO scale layouts) Anyway, I use the dense foam and absolutely love it! I do notice 'some' noise when running my engines back and forth (on all 4 feet of it), but it is about the same amount of noise that comes from a wood with homasote roadbed.

Like said above, different strokes for different folks. Personally, I will stick with the foam method (Unless something or someother way is shown to me).

[rrinker]

QUOTE: Originally posted by jxtrrx

Foam with no plywood backing actually increases noise. It acts as a sounding board that reverberates the vibration of the train noise. Even a 1/4" shee of plywood under it will deaden the sound.

I don't seem to have that problem, although I use Woodland Scenics foam roadbed, and I fasten the roadbed and track down with latex caulk, not a hard-drying adhesive like Liquid Nails. There's no drumming sounds, just the shuuuuuuuushing of the metal wheelsets (I replace all plastic wheels with metal) on the rail.

--Randy

[selector]

QUOTE: Originally posted by erikthered

Very helpful link, thanks!
Does foam do a lot or a little in noise reduction? Have seen some pro advice saying that one can place track directly on the foam... not sure this is a good idea. Any further thoughts?

Erik

It depends on your track roadbed and upon the track, itself. The foam has its own resonance, and will act as a soundboard for low frequencies. I have EZ-Track ballasted and placed directly on extruded foam. It is not a quiet arrangement. The plastic pre-ballast acts like a guitar soundbox. I believe, but cannot say for certain, that filling under the plastic ballast with a foam or gel will go a long way towards rendering more quiet. But, what a hassle!! Not to mention expense.

So, the 'good enough' solution will likely be cork or foam roadbed over the extruded foam, and then flex-track, not the pre-ballasted snap type.

[orsonroy]

QUOTE:
The foam presents no advantage for a large layout.

Not true. Most "large layouts" these days are linear walkaround, shelf-type layouts. In that sort of design, foam is actually superior to L girder and ply subroadbed. Adding brackets and foam is cheaper, faster to build, and simpler to build than traditional methods, meaning that you can get start laying track faster.

QUOTE:
It is a poor structural material.

Actually, it's pretty strong, has superior shock absorption properties than plaster, and is dimensionally stable, making it BETTER than (unsealed) wood. Besides, we're playing with little toy trains here, where an entire train MIGHT weigh five pounds. How much structural strength do we really need?

QUOTE:
A garage size layout will most likely have a peninsula which will need legs which means using wood anyway.

My new layout will be 14x25, around the walls with a center peninsula, and two levels. The only dimensional lumber I'll be needing is for the center peninsula. I'll use essentially the same construction technique I used on my last layout, which is a simple 2x2 studwall attached to the floor and ceiling/floor joists. From that I'll hang my drywall backdrop and shelf brackets.

Foam-based layouts AREN'T normally without ANY wood, unless you're talking about small, under the bed layouts. Most foam-based layouts have SOME wood in 'em, but that wood isn't the primary roadbed/subroadbed material. For my previous 12x25 three level layout, I think I had a grand total of 30 2x2's, 10 1x2's, and eight sheets of 1/4" plywood.

QUOTE:
If you are planning the Southern you will be doing mountains which are easier with open grid wood construction and plaster on screen wire or cardboard strips.

Two layouts ago, I had a freelanced WV/PA coal line which featured MANY large mountains, the largest of which was L shaped, 8' long on one leg, 12' long on the other, and rose 5' off the benchwork base. It was completely made of foam, except for a few plaster rock mold castings (the rest were carved foam, which is now my preferred rock construction technique). The entire mountain was removeable for access to a small staging yard inside. It weighed about 25 pounds.

Creating mountains out of foam is easy. Heck, virtually every Hollywood set you see these days (especially si fi stuff) are made from some sort of foam. Cut the foam into strips, lay them on top of each other, start sanding/shaping, and add paint and trees. No muss, no fuss, and no worrying about mixing plaster.

QUOTE:
I have worked with both wood and foam and have found no advantage in it.

I've worked with both too, and find foam to be a simpler, faster & easier to use, and all around better medium for most layout construction applications. But, different strokes and all that, I guess.

[orsonroy]

QUOTE: Originally posted by erikthered
Does foam do a lot or a little in noise reduction? Have seen some pro advice saying that one can place track directly on the foam... not sure this is a good idea. Any further thoughts?

Roadbed is a scenic element, and what it's made of is of little importance, at least from a mechanical standpoint. For roadbed, I actually make my own roadbed out of 1/2" thick foam (150 linear feet for $9 and about 15 minute's worth of worth), so ALL my track is laid "directly on the foam". My sidings and industrial spurs are laid directly to the foam benchwork base, just as probably 90% of the layouts ever built are laid directly onto the 4x8 plywood base.

Foam DOES amplify noise on a layout, especially if it's unsupported by underlayment plywood, and if there's no top layer of scenery. BUT...the noise isn't noticeable if you run slowly (30 SMPH or less), noise is reduced if you use wood under the foam (1/8" Masonite or 1/4" Lauan is more than enough), and noise is REALLY reduced if you use silicone or latex caulk to glue down your track. Use all three of the above techniques and add scenery, and foam layouts are at least as quiet as wood-based layouts.

[jxtrrx]

Foam with no plywood backing actually increases noise. It acts as a sounding board that reverberates the vibration of the train noise. Even a 1/4" shee of plywood under it will deaden the sound.

[hminky]

Go with wood you will be happier in the long run. The foam presents no advantage for a large layout.. It is a poor structural material. A garage size layout will most likely have a peninsula which will need legs which means using wood anyway. If you are planning the Southern you will be doing mountains which are easier with open grid wood construction and plaster on screen wire or cardboard strips.

I have worked with both wood and foam and have found no advantage in it. I cover my railroad construction at:

http://www.pacificcoastairlinerr.com/4x8/

Just a thought
Harold

[Anonymous]

you can lay it directly on the foam, I still recommend getting a Road bed of some kind tho because it will save ballast.
http://forums.railfan.net/forums.cgi?board=Southern
http://www.geocities.com/heartland/hills/3262/
http://www.srha.net/

[Anonymous]

I would think foam would do real good insulating noise.

QUOTE: Originally posted by erikthered

Very helpful link, thanks!
Does foam do a lot or a little in noise reduction? Have seen some pro advice saying that one can place track directly on the foam... not sure this is a good idea. Any further thoughts?

Erik

[Anonymous]

Very helpful link, thanks!
Does foam do a lot or a little in noise reduction? Have seen some pro advice saying that one can place track directly on the foam... not sure this is a good idea. Any further thoughts?

Erik

[orsonroy]

There are discussions on building foam-based layouts on this forum almost every week. Do a quick search for foam and start reading.

In short, if you have to start completely from scratch and buy everything new, foam is cheaper. If you're building a linear, shelf-styled layout, foam is all-around superior. If you're going to be building most of the layout yourself, foam is quicker and easier to deal with. If your modeling time is small, working foam is faster to dive in and out of, and will yield faster results.

If you're building a spaghetti bowl layout, running G-scale life steam, or have access to free wood, plaster and cardboard, and are retired, lumber and plaster is a superior building technique.

[Anonymous]

Erik,

Take a look at this, and see what you think.

http://www.trains.com/community/forum/topic.asp?TOPIC_ID=42598

[Anonymous]

Expert help needed!

I have been given permission by the local planning and zoning commission (my wife) to build a layout either using half our two car garage or our attic. This will be a BIG HO layout, modeling the Southern Railway circa 1955.

I've done the layout templating. I've bought books and consulted with the LHS dealer who is excited that I will single handedly put his kids through Harvard Law.

My question is this:

All the benchwork concerning the table top focusses on plywood 4 x 8 sheets. There's an add on in most of the books talking about "extruded insulation foam". This sounds like a neat idea...

What advice can you give me? Plywood... or foam?

Erik