I have 2 rather large oncidium both of which need repotted. On the outside are many new healthy roots. Do I cut when repotting or put them in the mix or just leave them out ? In my house I know they will soon dry up and I don't always have time to mist. I have heard outside roots are outside roots.
If the outside roots are already 3" long or so, then no real point in putting them in pot. And if they are already dried up/dead/crunchy -- as you mentioned quickly happens in your home -- cut them off. If they are new roots then put them in pot. They may be able to adapt.