The rule is a residential rental rule. If you rent it out, the rule applies. The ownership structure does not matter. I think there's actually a parallel rule

The rule is a residential rental rule. If you rent it out, the rule applies. The ownership structure does not matter. I think there's actually a parallel rule that theoretically applies to owner-occupied buildings, but for obvious reasons there's a lot less enforcement. Beyond real estate agents not listing an illegal bedroom as a bedroom, for example, nobody is going to hunt you down for using a non-bedroom as a sleeping place.