Here in Southern California all wood warps unless it is sealed with something. I say it is the dryness. So, in 1998 I built a special computer desk which later turned into a train workbench. Sense I had experience with specialized homemade furniture and prior layouts warping and the cork roadbed crumbling I tried Thompson's Water Seal left over from another project. I hit a home run! Wood does not move! Cork does not deteriorate. 19 years on my train workbench.
If you want to try it here is how you use it.
Make sure you use water soluble type. Makes clean-up easy. Last time I bought it it came in three tints plus clear in a metal gallon can. I bought it at Home Depot.
Build your bench work or module as usual. When you are past the glue and screw portion stop. Apply Thompson's over all wood including legs, braces, etc. Use a 0ne and two or three inch brush. Clean with water in sink. If you are going to paint over the water seal wait four days for the water seal to finish gassing off.
I now build in modules so they have legs and braces that show. I paint these and around the edges of the module rattle can flat black.. Looks good. On the inside of the module I paint rattle can white. However, I now build the rectangular portion with the track and scenery as an insert held in with screws but I still paint the underside white so I can see. The insert I still paint with water seal as I use thin plywood for the insert.
I don't like the weight of the modules, too heavy, so I am going to try the foams for the insert on new modules.
An Aside: The way I water seal the cork roadbed is
Buy a box at a time
Tear the entire box and finish the beveled edges (I'm in N Scale)
Use a shop rag saturated in water seal and rub along and all over. Hang on a line outside. Use gloves. When dry remove from line and leave in a sheltered area outside for four days to gas off. Fumes could be bad for you.
Your done. I put back in box
So, for me these two procedures are bulletproof for me. Give it a try and see what you think.
Mike Lee