Contemplating using OSB, 1” foam and homasote for under the rails

I use 1/2" OSB  and 3/4" high density foam board  for my layout.  The high density foam gives a little more resistance to weight pressed on it.  Just remember to glue down the foam,  then the track, it cuts down on the sound. I used acrylic caulking with silicone. Since you say you're using tubular track, you will probably have to screw them down.

Thank you Bill. How are you feeling?

Thanks for asking.  I'm doing great.  Had 12 weeks of cardiac rehab and I feel like it never happened.  Working on my layout adding mill factory buildings at this time. My son is a big help.

For my large tinplate layout (O and Std) I used 1/2" OSB with standard carpet padding glued to the OSB.  The carpet padding was sprayed green (latex) and I used a textured paint for the ballast. The track is all glued down.  I used screws to hold the track in place until the glue dried.  The carpet pad was inexpensive and the result is very quiet trains - except when the sound is turned up.

Thank you Mr. Fixit, I hadn’t considered carpet padding. Your layout looks great especially the way it contours around the room.