The Sims Complete Collection Players:

All files will be installed to the same directories listed below for legacy players, but you will not need to change paths.

C:\Program Files (x86)\Maxis\The Sims\

Exit your game before installing any files.

The Sims Legacy Players:

Tip: You may need to change permissions on your main installation folder to allow for file installation. This can be a complicated process and will not be explained in depth in this tutorial. You may need to change administrative permissions (Advanced for User & Creator Owner) Right Click Top Folder (The Sims or The Sims Legacy) Turn off Read-Only. If this does not change, then advanced permissions will need to be applied.

If playing The Sims Legacy (25th Birthday Bundle) downloaded from platforms such as EA, Steam, or Epic Games, install files following this general directory path:

EA

C:\Program Files\EA Games\The Sims Legacy\

Steam

C:\Program Files (x86)\Steam\steamapps\common\The Sims Legacy Collection

Epic Games

PLease let me know...

Others:

If you chose another directory path, you'll have to ascertain where to put things, this can still serve as a general guide.

All Players:

Tip: When installing create folders for the sites where you got the downloads. This becomes very useful.
You may create nested directories for everything except skins, roofs, houses, or families. Items installed in these folders will not be recognized if in subdirectories. Skins use a lot of redundant files across websites where we shared 3d Meshes for characters. Installing from various sites, you will often run into instances where some of the files are already in your Skins folder. This is nothing to be alarmed about.

Objects (.iff .far) - \Downloads\SimFreaks\
Floors (*.flr) - \GameData\Floors\SimFreaks\
Walls (*.wll) - \GameData\Walls\SimFreaks\
Roofs (.bmp) - \GameData\Roofs\ (No subdirectories allowed)
Skins (.cmx .skn .bmp) - \GameData\Skins\ (No subdirectories allowed)

Special Note: Skins come with 3 or more files:

.cmx - Combines meshes together
.skn - Contains a single 3D mesh file
.bmp - Texture for the 3D mesh file

Houses

Legacy Users

C:\Users\%USERPROFILE%\Saved Games\Electronic Arts\The Sims 25\UserData\Import

Complete Collection Users

C:\Program Files (x86)\Maxis\The Sims\UserData\Import

All Users

Launch the game, click the Import button (top of the neighborhood screen).

Houses (.iff)

Install to your UserData folders. Back up your existing House#.iff file first as it will completely overwrite it.

Family/Houses (.FAM)

These are unhoused families or families with houses. Install to the first UserData\Import folder.

CC Installation Instructions for Newbies by SimFreak & SimSlice