I have a large, unfinished basement. I love it, its my doggy-play room. Completely doggy-safe, no rooms in the main area, just one large space.
In the past, my four dogs could be down there to play with no accidents, all day. I crated them if I was going to give special treats like a Kong, but they were not crated every day. We introduced a new dog, Daisy, and have been crate training again for the safety of everyone until she can be trusted with all the dogs, if ever. (I have accepted that we may need to do this for safety as her and Josie don't get along all the time)
Daisy pees in the basement whenever she is left alone even for a MOMENT. She wont do it if I'm playing with the dogs down there, its only if she manages to sneak off when I'm doing something else. There is a baby-gate to keep her out of there now, but that means the other 4 can't freely go down there to play anymore. Another time that she does it: right after eating, if I'm upstairs and she finished eating, the dog door is closed. Does not do it if dog door is open. She knows better, just helps herself to the "basement bathroom" if she wants to.
I considered puppy pads but I did not want to encourage the behavior. I am trying diligently to just not let the situation happen, but in the future I really want to be able to let everyone have access to the basement. Is this wishful thinking with this dog? Accept that she doesn't understand and move on? She was an outdoor-only dog for her first 4 years of life so I have been very impressed with her other housebreaking achievements, never has had an accident in the house-area, just basement.
EDIT: My Lhasa (also spayed female) has now started marking in the basement all along my daughter's bedroom area, perhaps in response to Daisy's pee? Gotta love dogs.