if they know what you're up to, i'd suggest asking them to avoid that area for however long you'll need. i've had to deal with opening the circle [normally because i forgot the ale just outside the circle ^_^;] it can be time consuming to say the least, but it takes more energy when you close it. personally, to be safe i go around the circle once after closing the hole i had to cut.
when i cast indoors, my family stays in their rooms, as well as the cat, until they need something, or they hear us talking normally [meaning we're not saying 'thank you Lord and Lady for the season' instead it's 'i ran into so-and-so the other day'] at which point they ask if they can let the cat out, or grab something from the kitchen, or whatever. just figure out what is best in your opinion, but if they know you're pagan and need to cast a circle, kindly ask them to avoid the area for an hour or so, since it's holy ground [similar to church] and you can't have people wandering through.