More foam questions

Model Railroader Layouts and layout building
1

I have the styrofoam foam all set for the layout. It will serve as my sub-roadbed (cork will go on top). Here are my three questions:

  1. Along one side side is the tongue and on the other is a groove. Should I cut the tongue part off and put it along the backdrop so no one can see it?

  2. How do I fill the seams between the sheets of styrofoam–I got four sheets for my around the room layout?

  3. How long do I let the liquid nails sit to hold the styrofoam to the benchwork before working on the trackwork?

TIA!

Lee

2

Good questions. Welcome to the foam club.

  1. You can ignore the tongue and grooves unless they look bad. Then just slice them off

  2. I fill seams with ground good when I am doing scenery. If you are using 1 inch foam, you may want to reinforce the seams from underneath.

  3. It may take a week for the glue to set. You can pin it and start work. I use low temp hot melt glue to hold it toegether while it sets. I have even stuck shish kabob skewers in to hold things together. All you need is to keep from bumping it. When I am stacking it for scenery, I use all hot melt or it would take years to build a six foot mountain.

3

  1. Cutting the tongue off will make a smoother fit with the backdrop, but it may depend on what you will have in front of your backdrop may hide the small gap anyhow. I’d do it.

  2. What are you planning on using over the foam for a scenery base, just paint, sculptamold, plaster cloth? Unless your pieces are damaged on the edges it shouldn’t be much of a gap. If it is just paint with ground foam sprinkled on it you might want to fil the gap with latex caulk or spackling compound, either of the other should do it on their own.

  3. I’d let it sit overnight with some weight on it, books are good, if you use paint cans put something under them so they don’t leave a ring in your foam. Any I have done has been well adhered after that time. Might have been sooner, but I wasn’t back to work on it before that. Be sure you are using Liquid Nails for Projects as it does not eat foam, some of the others do.

Good luck,

4

Cutting the tounge off is really personal preference. I buy foam building insulation which has no tongue or groove. Its a little more pricey than styrofoam but much denser. I used Liguid Nails foamboard adhesive and let it dry overnight. I usually lay boards (1" x 3" work well) across the foam and clamp the ends of the board down until the adhesive sets up. I’ve had pretty good luck filling the seams with paintable caulk and smooth it out before it dries.