This was entirely written up by Christine11778; I only C+P it here so that it doesn’t get lost:

--

1. The first thing you need to do is find the “tray” folder:



2. Open the folder and go to the top and set “view” to “details” and then set “sort by” to “date modified”:



3. Now the files are sorted by date and time: the house I created is the eight files marked in purple (they all have the same modification date and there’s a “Blueprint” file among them).



(The files marked in red constitute a sim, not a lot – you can see that by the fact there’s a “householdbinary” file among them)

--

4. Make a rar/zip out of these and now you can share them like any other file –*the recipient only needs to unzip them and put the files in their Tray folder.



Thanks Christine, also for the screenshots!

I did this but I can´t find the houses inside the game, only rooms....

Are you trying to install a house or save one?

Sorry, I don't know where to look for "Create > Upload items (bottom right); can't find it on Main Menu, or my Neighborhood screen, or in Build/Buy.

veil, I was talking about the menu on this website, not the game =). The (now deleted) post above mine was asking for how/where to upload stuff here.

I downloaded Lassen's house today, unzipped the files, and moved all 7 files to a subfolder named Lassen in the Tray folder. I can't find the house in game. Is it because I put the files in a subfolder?

Yes. You can't subfolder Tray.

Thank you for the information.