Learn how to install houses for Sims 1 with this tutorial.

The Tutorial
  1. Step One: Save the File to Your Desktop
    Click on the download link or button and save the file to your  hard drive.
  2. Step Two: Extract File if in Archive Format
    Most custom content will come in archive format (.rar, .zip). If the file you downloaded is archived, extract it. (In Windows, you do this by right clicking and choosing “Extract Here” or “Extract to \”.)
  3. Step Three: Locate house.IFF File
    If you extract a file, it may have multiple files inside. The only one you should care about is the .IFF file. The file will always be named “house” followed by a number–for example, house01, house02, house03. The number is very important, because it tells you what lot the house falls on. For example, if the file is named house01, it goes on Lot 1. If the file is house03, then it falls on Lot 3. You need to know this number so you don’t accidentally erase a house you have in your game.
  4. Step Three: Navigate to the Program Files\Maxis\The Sims Folder
    Browse to The Sims folder on your system. You will see a set of folders in there labeled Userdata, followed by a number–for example, Userdata, Userdata 2, Userdata 3, etc. Just like with house.iff files, the numbers mean something. They refer to a neighborhood in your game. For example, Userdata is Neighborhood 1. Userdata 2 is Neighborhood 2. Userdata 3 is Neighborhood 3, etc., etc.
  5. Step Four: Place File Inside of Neighborhood Folder (Userdata#)
    Pick the Userdata folder of the neighborhood you want your house to appear in. You will see a folder marked “Houses.”
  6. Step Four: Place House.IFF File Inside of “Houses” Folder
    Put the house.iff inside of the houses folder.

Voila! That’s it! The next time you open your game, go to the neighborhood where you placed your house file, and you should see it there.