OK, so I have done a ton of reading and research. I just want to ask a couple of questions before I start my bench.
I have heard that some MRR’s use office ceiling tiles for roadbed. Anyone have any opinions about this?
I actually want to use Styrofoam for my roadbed (pink stuff). Is 1/4" ply a substantial thickness for supporting it? And is caulk the only way to adhere flex track to the surface? And if so, in the event of removing the track, will it damage the track and can it be reused?
The ceiling tile idea, from my experience in reading here, is far and away more oriented toward making rock cuts, or stacked for elevated plateaus and such…not for roadbed. It may work okay, but I would worry about it swelling if it soaks up any ballasting fixative you may use that is aqueous. If you use it, I would recommend sealing it with urethane or a varnish…depending on how it reacts to water. You might want to test it.
I happen to believe that you can safely support extruded foam with something as thin as 1/4" plwood of good grade, but it would need its own supports in the way of joists every 12" as a minimum. This would be for the thinner 1" styrofoam. Once you get into the 2" thickness and thicker, that stuff is plenty stiff on its own, and the 1/4 ply would be needed only as a nether surface protector or as a platform for mounting switch motors. You could slip the centers on joists out to 18" with impunity, and probably out to 24". You won’t be supporting your body weight on the foam anyway, so wider separations would be fine.
If you are patient about removing the track from properly applied caulking (thinly, that is…), you are going to do more damage to the foam on which the caulk is applied. I have taken up 3’ lengths of flex by see-sawing a thin metal spatula, such as a spackle spreader, under the ties, being careful to apply only a little upward pressure on the freed tracks with one hand and being careful to keep the blade oriented toward the caulk with the other.
It should be obvious that as you use less and less caulk, this task just gets easier. And that is my point…only enough to make it stick, and never so much that it forms little beads around the bases of the ties as you place the track into position over the caulking.
I have found that when the styrofoam is placed over an open area and not over the top of some thickness of plywood, that it creates a drumming sound. Very hollow sounding. My bench is built much like a wall with a frame and joists… I layed 1/4"plywood over the whole thing, except for a 2’ x 3’ section. Then I layed 2" pink styrofoam over the entire bench. I used the 2" so I can carve down… When an empty boxcar rolled over the section that didn’t have plywood, the wheels on the track resonated a loud hollow sound, compared to practically no sound on the rest of the layout.