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Plywood or Foam Insulation Board?

New member to the Online Model Train Club Chris Peterson has this question for readers:

“Quick question – is foam insulating board better than using ply-wood? I will be building height on top using layers of extruded foam so I can carve into it. Is this the right way? I like that it’s lightweight. Is there any fire danger?”

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13 Responses to Plywood or Foam Insulation Board?

  • George Kern says:

    If you want, replace the plywood with a sub floor of 1×4 framework. This allows for a light base and you still have the abilities to layer with foam board and add all the contour you want. Plus you have better axes to the wiring.

  • Geoff says:

    The group that I am part of favours making rectangular frames from 3/4 inch plywood cut into 4 inch strips, and gluing 2 inch foam on top as the base. I am planning to use 1 inch foam, but with. Hardboard subbase on top of the frame. This is the insulating foam used in housing. So I wouldn’t think there is a fire danger.

    Pros lightweight, easy to shape the foam to fit the frame, and easy to carve into.

    Cons have to glue the track and roadbed instead of pinning it, if using point motors mounted underneath may need to make longer pins from piano wire, more difficult to fix the point motor to the base.(or to fix a manual switch alongside the point)

    The foam is not as strong, but unless you plan to rest your elbows on it that won’t matter.

  • Eugene Hansen says:

    I use Homosote with 1×4″ framing. Easier than plywood for inserting screws and better soundproofing.

  • Frank B says:

    The first question: is this for a permanent layout at home, or for a portable layout you can move and put away, or even take to exhibitions ?

    If it is permanent at home (and you don’t plan to move (ever !-)), then weight is not important.
    But when wiring up and mounting turnouts etc, it will be much easier to make holes through the baseboard if it is a thin and/or lightweight material.

    Thin plywood on a wooden frame will be light and portable, and easy to cut through for wiring and turnouts etc.
    And foam on top for landscaping will be fine. However, for any ramps and gradients, it is usual to make the track base from plywood sections and mount it securely before filling in the scenic hills.

    It will probably be worthwhile to get a basic book on model railroad layout building and wiring to get a grasp in advance of all the fundamental necessities and considerations.

    Fire safety: no smoking or naked flames near any layout ! Most kinds of plastic foam are flammable, as are many other components (wood, paper, card, plastic).

  • phil johnson says:

    I use 3/8″ plywood for base. Carve 2″ blue/pink foam to shape then glue to plywood. For ground throw I use .030 plastic sheet glued to the foam

  • Robert Schworm says:

    I use 1.2 inch plywood over a open girder benchwork. Then top it with 1 inch extruded foam baord (gren or blue) Define your track plan on this foam, use Liquid Nails Foam for Projects. Lay a smear of this adhesive along your track centers and fix your foam raodbed (woodland scenics). Then pin your track down, with about 1 inch small head nails. Press down thru the member, the roadbed, and thru the smear layer into the foam. The smear will grab those nails like crazy, but allow them to be pulled up to move the track as required. Do not spike your track into plywood, you will go crazy pulling it up. Do not ballast for at least 1 year until you are positive your rolling stock has no issues with the tracks.

  • Mike says:

    2 inch foam is the answer for many reasons: light weight, strong with 1×4 supports every 2 feet and 1×6 frame. Easy to drop feeders through, quieter than wood, some great building tips on my channel. Go to youtube, search for “captain mikie” click on VIDEOS.

  • Steve Hubard says:

    I prefer plywood and spline for sub roadbed. I am not fond of foam for laying track as it needs glued down and is a PITA to remove if required, not to mention messy. I also like nailing my track down just like the prototype does. I plan on trying multiple scenery methods on my new layout I am currently building including 2″ building foam.

  • Morgan Bilbo, PRR fan says:

    IMHO neither is a preference. It depends on what others have suggested. An individual must decide for him/her self. There are advantages and disadvantages to foam as well as plywood. There is also steel. ?? A base of plywood can support foam or homasote or other materials. The foam in question must be the pink/Home-Depot/Owens Corning or blue/Lowes/DuPont. ?? Do not use the white/packing material. Most of the comments above are good, I am only helping out here.

  • James King says:

    If you use the pink or blue foam make sure you reinforce the sides with wood. Foam does have a tendency to warp, as does wood. I suggest if you want to keep weight down, build an open frame to support the layout, cover with 1/4″ plywood subfloor and glue a base sheet of 2″ foam. Drilling for wiring is fairly easy and using the thicker foam allows you to cut away sections for lakes and rivers.

  • Steve B. says:

    I wood suggest using 3/8 OSB sheet instead of 3/8 plywood. I is ridgid in 2 directions and is about 1/2 the cost. OSB stands for Oriented Strand Board.

  • Chris Manvell says:

    My first layout (Z-Scale) was on 1cm MDF with 3mm cork tiles glued on top and a 181cm by 61cm open frame, 7.5sm high. There was no need for battens. The final weight of the layout was 20kg (including a fold-out control paned and thin ply covers) and it was used for exhibitions only. It worked really well but I won’t do it again.
    Having lost the ability to drive, my current idea is to build an 88cm x 50cm portable layout in an aluminium case. The baseboard is 1″ Kingspan (330gm) resting flush with the top of the bottom half of the 20cm high case. The z scale track was attached to the cork with office double-sided adhesive tape. Even though the cork was sealed with matt varnish this was a disaster. So, I’m going to start over again with a stronger tape. You can see both layouts on my website.

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