My plan... for what it's worth...my oldest is only 10!

is that if they have to live at home outside of high school is that they pay rent.
Not to be mean, or even "recoup" the costs. Quite the opposite, to be helpful. Because if you are not used to paying rent... it is very hard to leave.
My best friend had this problem. Lived at home until 24. Hated every minute of it. Made a decent income for a single girl, but spent money on a nicer car, nicer lifestyle than she could afford. Because well, in your 20's you shouldn't live as well as your parents do in their 40's! Not setting money aside for housing she "felt" like she couldn't afford to move out.
I plan to charge rent, to get my young adult children in tune with spending their cash on living expenses. So it can't be all blown in make up, eating out, nice cars. They will be living a lifestyle in their means, not artificially so.
The good news is that I would chuck the "rent" into savings. So when they do move out, they have a nice chunk saved up, for deposit, furniture, whatever they need. And they will be in the "habit" already of using their funds (no matter how meager) for housing.
My DH and I kind of did this when we bought our 1st home. Was going to cost $1000/mo for a mortgage, but we only paid $600/mo in rent. To "get used to" what $1000 felt like, we simply socked an extra $400/mo in savings. That way we were in the habit of spending $1000/mo and it wasn't a shock. We "felt" the sacrifices it would take to afford our housing. Better yet, a little extra money saved up!
I imagine if my child were in dire straights, I would take them in rent free. But as soon as they could afford more than a basics... (like going out to eat, movies, fancy grooming, a "nicer" car) it would be time to charge rent.
We have twin 26yr old. girls who have moved back home since graduating college. One is a full time teacher and gets paid pretty well. The other is finishing her masters at a local University and works full time in the school system aiding Special Needs students but makes a meager wage. It gives her the flexibility to takes her classes. I'm a sahm so I shop for & cook all meals, wash/iron everyones clothes, clean etc. They pay for anything related to their car, and their personal bills. They of course buy their own clothes and personal items. My question is, do your kids pay rent? What other things do your older kids who live home do? My DH says I should stop doing their laundry, but if I didn't the washer/dryer would be going 24/7 and the water bill would be $$$. I'm feeling like the maid, and frankly they are not very appreciative (but that's another dilema). Whew.....felt good to vent a little