I know I have seen this somewhere before. I just finished my support structure for my board, and I have the plywood on the support. Now I need to get it leveled out, I looked at Home Depot and Lowes for Styrofoam, only sell the soft (insultaion) foam, any suggestions on where I can get this. I need 3 - 4'x8' sheets for my layout. Then I will start buildin up.
Johnny let me welcome you to train board. A few questions 1. Are you using the plywood as a base or are you looking for the Styrofoam as a base? 2. What Scale are you planning to start this layout in, as that should determine what kind of weight the layout must support? I am modeling in N-Scale and I used the ½ inch blue insulation styrofoam from Lowes they sell it in ½ inch and 1 inch thickness if I remember correctly, if you are using the plywood as a base and putting the styrofoam on top of it either of these will do fine. Just depends on what you plan to do with some scenery I.E. lakes, ponds, rivers and so forth and how deep you want these to be. Mine is ½ inch plywood and ½ inch styrofoam leaving me ½ inch for making a lake and a river and if needed I can cut a hole in the plywood giving me another ½ inch and just placing something under the hole to support the water effects if I need it. Or possible you could double up on the layers of foam 1inch with another ½ inch on top or 2 1inch sheets on top of each other also there are various ways so long as there is not too much weight involved and take care with leaning on the table top (do not want to put your hand or something through the top of the layout). I can forget things sometimes so I saved myself from some possible future disasters. There are books on building layouts with just foam and strengthen that foam to not warp and retain its flat and level form. Using more foam cut and placed as support bracing. Here are a couple of pictures of my foam glued to the plywood and a sec where I built up the foam to add a grade and so to speak bluffs on one end. In this next Photo you can see where I glued a second ½ inch of foam to elevate this side of the layout and to raise the bluffs above the level of the track and save on materials i used several section of ½ inch foam and put sculptamold on top of that. In previous discussions I was asked these same things and I am pointing out what was pointed out to me,, I can not seem to find those topics after doing a few searches. Also you might want to stay away from the beaded white styrofoam due to it leaving small white beads every when cut. I painted a beige latex paint over the foam to help keep it sealed from water and other liquid building materials.
The frame is 2x4's and the plywood (4x8x 1/2") is the table top. I am sure this frame could support a small adult walking across it. I wanted to use the foam to level out the plywood (actually its GBX), then use the foam pieces to build up mountains, carve out lakes, and raise the track.
I have been successful on at least two model railroads doing what you are proposing - using expanded polystyrene foam supported on plywood - as the base of my railroad. I have actually been able to get away with 1/4" plywood provided it is reasonably well supported with some internal 1x4 cross members. I usually just used several layers of 1" foam laminated into layers. Good old white glue works okay, although I prefer to use the model railroads best friend, Liquid Nails. If you make the base a few inches thick, you can carve the contours with an old serrated knife and a wood rasp. Just put some weight on the layers while the cement sets. Good luck.
I personally didn't like the result of gluing large sheets of foam to large sheets of plywood. No matter how much weight I put on it I could never get a good tight seal between the two. For this reason I'm not planning on using any (or at least not much) foam on my layout).
