I think the standard route is to buy a big-ass house which will fit all your future-kids. But, when they fly out of the nest, you are left with a house too big for you to maintain

You have no children yet, and you are planning double digits. Let's assume that means 10 children, and that there will be 2 years intervals between their births, and they will stay with you till about 20. That means it will be 40 years later when the last child flies out of the nest. Also, you might want to provide a backup solution for children who fails to become financially independent at 20.

If you are going to build a big house, I would probably try making it modular -- to build it in a way that if in the future you build two or three internal walls, you will effectively split the house into two or three independent households. Each of them with its own kitchen, bathroom, etc. (With so many people, you will need multiple bathrooms anyway. So you just have to place them strategically.) So you could later split the house, keep one of the parts, and provide other parts to some of your children -- or if they are not interested, you can rent of sell them to someone else. (Also this provides you an alternative if you later decide you actually don't want so many children.)

Depending on where you are, the limiting factor might be not your willingness to let your children live on their own, but your legal right to do so.

Christopher Alexander's Towns Buildings Construction has a treasure trove of advice for your case. Applicable patterns that come to mind:

• House for a small family
• Intimacy gradient (rooms more distant from the entrance should be smaller and more intimate
• Couples Realm
• Connected Play and Children's Realm (the basic pattern is that all rooms/areas used by children basically (should) form a contiguous realm - simply because that's what will inevitably happen anyway. You will recognize it by the toys littering this connected area)
• Sleeping to the East
• Teenager's Cottage (this might be the minimum of what you might intend/do)
• House a for a single Person
• House for a couple
• Home Workshop
• Master and Apprentice
• Teenagers Society
• Public Outdoor Room (space between buildings should form 'outdoor rooms' with recognizable sides and 'doors/windows' instead of just gaps between buildings)
• Adventure Playground

See here for a list of the patterns: https://www.patternlanguage.com/apl/aplsummary.htm

mostly worth adding: it depends on the kid.

My brother moved out of home at age 16 and it was an excellent choice. My sister was 21, I stayed till 24. This was also a good choice.

I started learning to manage assets when I was 13. I could have started sooner. I was doing things on my own from 18.

With power comes responsibility. It's a great idea to give someone their own space; so long as you are sure they are responsible enough not to wire electronics badly; or start a fire. I would suggest a certain level of adult-ness is required to not accidentally kill one's self. given that we live in the age of big metal things on wheels that you control with your fingers to take you across the country, and electron flows in our streets that can kill people in a blink. flammable gas flowing around the place too, sharp objects (and weapons available generally), the ability to play music loud enough to deafen ourselves by accident... Just to name a few.

Now I have no reason to think that bright lw-kids will suffer risk to their health like that; but if they are self-raising they might not have the right guidance to get it right first time. By all means people should make mistakes; but only mistakes that don't kill, or seriously wound you in the process. Those mistakes are the good ones that we can learn from.

There are multiple stages or degrees of "living alone", and it's very difficult to satisfy all of them without a number of physical moves that you can't buy space very far in advance.

a) shared room with parents b) shared room with siblings c) separate space/room, shared meal preparation and amenities d) separate house/apartment, walking distance for many shared meals and events e) separate household, rare visits f) separate household, moving through it's own phases a-e.

It's hard to know when each of these phases will become appropriate to an individual, nor the individual preferences for variation in distance and specifics of house. Also, building a house is harder than you think.

I think this sounds like a very cool idea, but I have some questions about potential difficulties.

My first thought was that this sounds expensive. Have you checked on the costs vs. your resources, admitting that both of them will be estimates?

Are you planning on adopting if it looks like you're not likely to have that many biological descendants?

Have you thought about how to teach your children housekeeping and home maintenance, both the facts and the habits?

Lots of kids wouldn't want to live alone even at an age at which they safely could.

I would assume that most guys who have such an idea and propose it to their wife wouldn't have the wife accept the idea.

At what age would you be confident that your child could handle living alone-ish?

Do you mean the age where the child wants to live alone or the age where they could handle it without too much damage?

How much distance between the houses are you talking about?