To foam or not to foam?

[jxtrrx]

My current layout is 1” pink extruded foam over ¼” plywood. I have been a big believer in foam because I really liked being able to experiment with a track plan by laying some track on foam, temporarily tacking it with Atlas nails, and being able to easily move things around. Once achieving good positions, lay roadbed and then glue everything. Now that I have discovered XtrkCad, I do all my track experimenting on the computer, and when I lay track it’s perfect.

So now I’m getting ready to do a new (much larger) layout. I’m thinking I may not use foam at all… but cork roadbed on plywood. As I see it here are the pros and cons of foam:

Pro:
Light weight (I don’t care, I’m not moving it).
Easy to “dig out” for ditches or build up for mountains (could still use some for build up… I like hard shell better for mountains and contours, foam looks too smooth to me).
Easy to stick holes in for trees, wires, etc.

Con:
Introduces problems (solvable, yes, but more difficult) with installing Tortoises.
Sound vibrator (especially without plywood under).
Easy to nick and damage especially on corners and edges.
Expensive.

What does everyone’s experience say? Will I regret not using foam? What am I overlooking?

Thanks for any discussion on the topic.

[MisterBeasley]

1/4 inch plywood by itself doesn't give you much strength, so you will need a lot of bracing below it. When you go to 1/2 inch or 3/4 inch, you lose the cost battle to foam.

I personally use 2-inch foam with no plywood. I really like the ease of wiring and manipulating it to change levels. Since I have a free-standing layout on wheels, lightness is important, but I think the ease of use battle goes to foam.

[jxtrrx]

Thanks Mr. B. Good points. With my larger area, I'm looking at buying either more (thicker) plywood or more foam. I knew the 1/4" by itself wasn't going to do it.

[rrinker]

I dunno, I still don't have any excessive noise without any plywood undermy foam. 2: foam, woodland scenics foam roadbed (HO on mains, on sidings for a lower profile) and I use latex caulk for roadbed to foam and trakc to roadbed. The only noise my trains make is the sssssssssssss of metal wheels on metal rails. Running a good quality loco around with no cars, and all you hear is the motor humming, or the sound effects if it's a sound-equipped loco.
My substructure is 1x4 on 16" centers, 2" foam is fastened to the 1x4 benchwok with elmer's yellow glue.

--Randy

[Anonymous]

I have just finished my first of several bench work, 3 x 8. 1x4 construction as well, cross members ever 16 inch. I used some high grade 3/8 ply to sheet the top, and 3 inch foam glued to it.

I was going to do without the plywood sheet, but it helps keep the bench work true.

Using a bench with cross members and foam, you can still secure anchors and more supports through the foam into the cross members for raising terrain, or roadbeds.

This is my first layout with foam though.

[orsonroy]

I've built several all-foam layouts and/or module sections, and will never go back to "traditional" layout construction. My basic benchwork (I'm a walkaround shelf layout-type modeler) is 1/4" plywood, 2" foam, and metal shelf brackets. The construction is quick, inexpensive, and completely effective (my last layout was a 8x25 three level, and my new one will be a 12x25 two level). If I "need" wood anywhere on my layout, I use nothing more high-tech than 1x2s and 2x2s.

[jmac77]

I have used 3/4 in plywood and 1x4 for subroadbed with 2in foam glued to it with cork roadbed glued to foam and has done fine for yr or so it's been in place. My layout is in my garage and it's "air condotioned" but it's still in North Fla and we do get heat and humidity by the ton! This I feel is probaby over kill but it's quiet and no warping. Make it tougher to put in Tortoise sw mach however. Nothing's perfect

jim

[dgwinup]

I think you would regret not using the foam. Foam is so easy to work with, especially for scenery construction. 2" foam is very stable and requires only minimal support.

Many modelers apply foam over plywood. Except for the larger scales, I think this is an unnecessary step, but it has some advantages as others have already pointed out.

You can build a simple perimeter frame of 1x3 lumber and cut 2" foam to fit on top of the frame. Glue the foam directly to the frame. Depending on how wide your frame is, crossmembers may or may not be needed. If your frame is less than 18" wide, crossmembers are not needed. Over 18", crossmembers add additional support.

To protect the edges of the foam, profile boards made from masonite or luan plywood can be screwed and/or glued to the sides of the frame. If the layout is not going to bemoved, there is less risk of damaging the foam.

Sound is transmitted easily through solid surfaces. The use of Liquid Nails or latex caulks and adhesive to glue roadbed and track helps prevent sound transmission because it retains some flex after it's dry. Often, foam solidly glued to plywood adds to sound transmission.

I think it would be a mistake for you to avoid using foam. It is such an easy product to work with.

Have fun building your layout.

Darrell, quiet...for now

[jxtrrx]

Thanks everyone for the good feedback. As I check local lumber yards, I'm finding that 2" foam is slightly more expensive that 3/4" plywood. But the ease-of-use thing you're all talking about may be the over-riding factor. Appreciate the comments!

[CP5170]

What about 1" foam glued to 1/4" plywood? I am thinking about doing this in my hidden staging area.

Your thoughts, please...Ken

[jmozz]

what size metal shelf brackets do you use how wide can you come off the wall jmozz

[orsonroy]

QUOTE: Originally posted by jmozz

what size metal shelf brackets do you use how wide can you come off the wall jmozz

My brackets are the simple 10"x12" stamped steel "U" channel L brackets. No fancy (or expensive) track shelving system was required. Most of my shelves were 1' wide, so the brackets held them just fine. On areas where I needed to widen the shelving past 16" or so, I used 1/4" pine plywood (less flex than Lauan) under the 2" foam. I was able to easily extend to 24" in these areas, without sagging.

[orsonroy]

QUOTE: Originally posted by CP5170

What about 1" foam glued to 1/4" plywood? I am thinking about doing this in my hidden staging area.

Your thoughts, please...Ken

I use 1" foam and 1/4" plywood for the base layer of my Ntrak modules. It works great. So long as you've got some bracing under the ply (16" or 24" OC), using 1" foam should be plenty. I generally use 2" foam for it's added stiffness and for the depth that I can cut into it, but I realized than most of it's potential went to waste on my relatively flat layouts (I model central Illinois in both HO and N). So I switched to 1" on my N modules, and will be switching to 1-1/2" foam on my new home HO layout.

[Anonymous]

I use 1" foam and 3/4" plywood on my around-the-room layout. Overkill? You bet, but I can STAND on my layout, can you? A part of my layout is 38" deep, so I plan on having to at least lean on a good part of the layout.

If you will EVER have young kids around your layout, and you're not there, plan on them climbing up on the layout to retrieve a car.

Mark in Utah

P.S. Sound transmission is nil.

Mark in Utah

[orsonroy]

QUOTE: Originally posted by mark_in_utah

I use 1" foam and 3/4" plywood on my around-the-room layout. Overkill? You bet, but I can STAND on my layout, can you? A part of my layout is 38" deep, so I plan on having to at least lean on a good part of the layout.
Mark in Utah

My old layout's lower level yard was between two to three feet wide, and was nothing more than 1/4" pine plywood and 2" foam, on a 2x2 box frame with 24" centers. I'm 6'2" and 225, and I could walk on it all day. You don't need 3/4" ply for strength!

[rockythegoat]

I've had excellent luck with 2 inch foam on sheet plywood, had all of the "Pros" you mentioned. Never really noticed sound being a large problem, and I did have a section unsupported by plywood.