Jay Francis, When my wife had the train room built for me over the new 3 car garage, I did to see some of the progress when home on some weekends. The construction was standard, per code, with decking laid directly onto the joists, standard pink lay-in insulation, 12" inside 16" joists, and poly vapor barrier beneath the floor decking. Ceiling of garage below is 1/2 inch drywall into joists. When I had the time home, managing local project at Tinker AFB, I lay down 4" compressed particle, interlock flooring planks on top of normal under-lay pad. Noise from the running of several trains at same time is not noticeable in the below garage, and with the man door at foot of the stairs is closed, wife says she cannot tell when I am up in the train room running. Didn't really consider anything special, being built over garage, but seems more than adequate. I really like the wooden floor. Easy to get around on under the layout and don't loose things when they are dropped on floor. Easy to vacuum and spills clean up easy.
Jesse TCA
