I am considering following MR editor David Popp and use polystyrene insulation board on my HO layout. Good idea?
There are numerous threads here on this site discussing foam insulation for layouts. Use the “search” function, and you’ll be inundated with useful information regarding foam for layouts.
Rotor
Here’s a link to some past threads.
http://cs.trains.com/search/SearchResults.aspx?q=foam+insulation&f=&u=
Rotor
tl38:
It’s a good method which some people like and some people don’t like. I think, in this world, there are those who like to carve and those who like to build up.
So, would you rather carve a duck out of soap or model it in clay? I’d rather use the clay, and I prefer to build up hills with minimal carving. Other people, who love to carve, will like foam better.
I will say that building a whole table out of foam is easy and quick and gives you lots of freedom to carve terrain. (the carving process, for me, has not proven to be quick, however).
First, you want the blue or pink insulating foamboard used in construction. It’s a polyurethane foam that is strong and cuts cleanly. DON’T use the white crumbly polystyrene “beadboard”. It isn’t strong, and it makes a terrible mess when you cut or shape it.
Second. Understand that the foamboard WON’T take fasteners of any kind. You cannot nail your track down to it, you can’t mount switch machines to it with screws, you cannot secure terminal blocks, wire looms, or anything else to the underside. Everything has to be glued down. Latex caulk is your friend.
Third, the edges of the foam will crumple when you lean on them. They need some wood framing around them for protection.
I made wood frames from 4 " pine, and put a layer of plywood under the foam to stiffen the wood frames and give me something to take fasteners on the bottom of the layout. I made roadbed out of pine and glued it to the foam. Nail or spike track down on the pine.
I used a Craigslist band saw to resaw ordinary 3/4" pine boards to 1/4" for the road bed. I cut the roadbed to size and round curves with the bandsaw. A router mounted in a router table beveled the edges of the roadbed.
I use pink foam, and I’m very happy with it. It’s strong, stiff and light, yet it can be cut with a knife or hot-wire cutter. If you’re going to build a fundamentally “flat” layout, or a layout with large flat sections, then this is a good material. It’s much lighter and generally easier to work with than a sheet of 3/4 inch plywood.
David made some good points about its limitations, though. Everything has to be glued. Another issue which may (or may not) bother you is that you can’t climb on it. So, don’t build a foam layout and expect to climb on top of it to reach the back. Unlike plywood, if you kneel on the stuff you’ll crush it. (Congratulations. You’ve just made a pond!)
Pink foam and blue foam are the same. One’s made by Dow, and the other by Owens-Corning. It just depends on where you get it. And speaking of “getting it,” the climate of the Southwest, including southern California, is such that this product is not typically found at building supply places like it is in the rest of the country.
Great idea for making a pond! Beats gouging, scraping and sanding!