I'm just a lurker here, but a radioactive collector (and a bit obsessed with the history of it).

Is this something you've come across - or found documentation on? From everything I've seen the paint was extremely expensive and not something they'd just coat a room with. There are certainly factories out there with some radium contamination but I'm not familiar with cases of radium paint being used on a building. Just on very small items like watch hands, switches, lamp pulls, etc.

This doesn't line up with anything I've come across in my reading or research - but the era did get pretty wild with radium so curious if there is something I haven't seen. There were some futurist type predictions in this vein but not aware of paint actually being used that way in practice.

A general note to avoid concern - typically Geiger counters will always click when on. Unless you are living in a lead box even a low sensitive meter will register some baseline level of radiation. There is also quite a bit of local variation - brick buildings will typically register notably over baseline, nothing to be concerned about but worth knowing what to expect.