A closure period marks a site as shut between two dates. You set them under Settings > Locations. The rota respects them the same way task generation does.
What changes
Creating a shift inside a closure warns you.
Publishing a week that overlaps one lists the affected days in the confirmation.
The unfilled-shift alert skips closed dates entirely, so a three-week refurbishment does not send a manager the same alert every morning.
Nothing is refused
You can still roster people into a closure, deliberately. A site closed to customers still has people in it: the deep clean, the stocktake, the contractors, the deliveries. That is the same reason a closure lets you keep specific routines running.
Check-ins during a closure
They work normally and are logged normally. Somebody who is in the building has worked, whether or not the doors were open.