This is my first HO scale building that I've ever built, it's for a new layout I'm just starting. I'm not really sure of the types of roofing material that would have been used on the bus canopy shelters? I was thinking of tar paper on the main building as well as adding an exhaust fan and an A/C unit. Any ideas or recommendations?
I might guess it would have had a tar and aggregate coating. The roof looks good as is now. After you add those details, even better.
You could use light gray N scale ballast to copy the aggregate coating. In more current times there are aluminum-based coatings, white elastomeric coatings, and the sprayed on foam coatings-which turn a dirty white after a few years.
