To Build or Not Build a Frame?

[RobertInOntario]

I’ve made a small 3x5’ layout out of insulation foam board that I bought at Home Depot. The layout is simply set up on a portable table in the basement and I’ve operated the layout this way for the past 8-10 months. (It's a British 00 layout, which is similar to HO.)

Is it necessary to create a frame around (& under) the layout? I’ve been thinking of doing this but haven’t got around to it. This would obviously give the layout more support and strength. And, if so, what’s the minimum thickness of a sheet of plywood that I could get away with (for underneath the layout)?

The layout seems fairly sturdy as it is, so I’m still wondering if this extra step is necessary or not.

Thanks in advance.

Rob