Why is the treehouse so big??

Your sims can hangout there and I think it's a woohoo spot too. It's not scalable for those two reasons.🙂

The treehouse is unscalable gameplay! I love the treehouse...use to have one as a kid just like it. My real treehouse as a child was in a larger Hemlock tree with wooden footsteps nailed into the tree from the base up and tire swing. These structures can not be downsized because your sims( kids- and up)  can do activities in the treehouse. It's like a residential lot without all the perks...I don't think you can cook food up in there.🙂

I tend to put it in public parks where there is plenty of room. I get the whole family, or family and friends, to go down there one day and have a day building the treehouse as a community project, have a bbq etc, then it is there for any kids (or grown ups lol) to play in.

Same here, I placed it in an empty lot, which I turned into a park.  There's just no other choice, unless you live underground or in a tiny home.

I think it's big too, compared with the TS3 tree house. But this time it's much more flexible, and a bunch of sims can gather up there. In TS3 I think it was just one or two kids at the time. While I think most RL kids will have a smaller version, I see them as different purposes. And the idea of building it on community lots I might copy, hopefully kids (or older even) can go there to spend the night in a sleeping bag even if it's not on a residential lot.

For the size of it, I mine as well build a second residence off the back of the primary family home! I don’t really want it on a community lot as I’ll likely never use it. I might have to remove it. So disappointing. Also my adult sims autonomously try and sleep in it (over their own bed) more than. Kids playing up there. 

The last one is the first one i did fit it in a tight spot. After that it became easy to fit the treehouse in any 30x20 lot. I wouldnt go smaller than that, but i could. Actually i might try the next one lol

(edit;)btw i never use moveobjects as it makes editing impossible for me and it leaves objects hanging in the air 

In sims 3 multiple kids in the same family could hang out in the treehouse. I think you can invite anybody up there in both versions. Sleeping, homework, escapism(playtime) for kids and adults are activities you can do and basic socializing.....🙂

I love the building animation with this gameplay. The construction has a function! ❤️

I need to test out the sack lunch and see if my sim can eat up there as long as there is seating.

The best place to build the treehouse for residential gameplay is on a residential lot : 40 x 50 lot or 60 x60. The smallest residential lot would be a 30x30 lot with a small house and lager backyard. It's all about the backyard space for residential, so a large, empty flat backyard is better.

I still have this one placed in a single family home lot in San Sequoia, Gilbert Gardens, 13 Acacia Avenue. 

I did need to make use of the standard bb.moveobjects cheat, and then the Alt + mouse to fine tune it's specific location, though, since as you can see it is a tight fit. Still, the family seems to enjoy it lots. 

They can indeed sleep on the community lot. There is a task in one of the kids aspirations which requires sleeping a night in the treehouse and I've had my kids do that at the park successfully (I had to stay at the lot with them rather than controlling other sims at home).