Accessible Thumbturns
At least once a month someone asks me whether it's ok to use a deadbolt with a thumbturn on a door that is required to be accessible. It took some digging to get a definitive answer, because the accessibility standards don't specify a certain dimension that would be acceptable for the thumbturn. The ADA guidelines and ICC A117.1 both state that hardware has to be operable without tight grasping, pinching, or twisting of the wrist, but that still leaves a lot up to interpretation.