Is this door from another part of the house to the basement ? Or is this door from the basement to the outside ? CY: The door opens into the kitchen, is at the top of the cellar stairs.
Either way you might want to investigate the building life safety code for your area, installing a lock that high up on the door may violate safety regulations if this door is considered to be one of the only exits from the basement... CY: That is a good question. I don't think it's emergency egress. I don't know if there is another way out of the cellar, though.
Ask this woman if she wants her kids to be hurt or killed if they wind up on the locked side of this door and can't reach the thumbturn or don't have a key during a fire or carbon monoxide gas buildup ??? CY: An intersting thought.
Is this person trying to keep people out of the basement, or keep people who might get into the basement out of the house ??? CY: Both. She is trying to keep burglars from getting through the cellar to th ehouse, and trying to keep the kids (about 1 and 4 at the moment) out of the cellar when it's not play time.
Evan, ~~formerly a manitenance man, now a college student...