I’m starting to seriously think again about building a model railroad layout in the basement. I found my old data files from when I worked on this 10 years ago. Here are a few virtual photos of the layout room showing the duct work, joists and relevant plumbing, along with the stud walls I would add.
Overall room size is 21′ long by 13’8″ wide (before putting up stud walls). Height from floor to bottom of ceiling joists is just under 7′.