Foundation

Foundations are an architectural object in The Sims 2, The Sims 3 and The Sims 4, used to raise the level of the main floor. They can be used over uneven terrain. In The Sims 2, unpatched versions of The Sims 3 base game, and The Sims 3 for console, foundations are required for the construction of basements.

The foundation tool is used by clicking and dragging a square area on the terrain, or by clicking on a room and raising it up using the arrow that appears in its center. There is also a diagonal foundation tool. Stairs, generally modular, can provide access to floors built on top of the foundation.

Players can choose either a decking foundation, a patio foundation, an elevated foundation, a foundation for a stage or a brick foundation.

The Sims 2
Foundations were first introduced in The Sims 2, and allowed for houses to be elevated some distance above the ground. The walls of a foundation can be repainted like any other wall, but they will not be treated as proper walls by the game, and thus will not provide protection from the weather if Seasons is installed. Foundation walls also cannot have wall objects placed on them.

Foundations will create a small crawl space between the floor above and the terrain below. Objects cannot be placed in the crawl space without the use of the moveobjects cheat. The terrain can still be edited underneath the foundation, and floor tiles can be added to the crawl space, although Sims will not be able to see or use them.

A foundation's walls technically extends past the lowest point on the lot. This can be seen when building a basement using foundations, or when digging beneath a foundation.

The Sims 3
Foundations in The Sims 3 are identical to those in The Sims 2. With the Late Night patch, a new platform tool is introduced. It allows the player to create a platform elevated by a single "step" for Sims to use. Unlike the foundation tool, it doesn't require stairs to walk across it.

The Sims 4
Foundations in The Sims 4 function differently to those of previous games. There is no longer a dedicated foundation tool; foundations are now created by selecting a room, and dragging the arrow that appears in its center up or down. Foundations can be adjusted to any height, and even sunken into the ground. However, a sunken foundation will distort the terrain to accommodate it. Prior to patch 73, all buildings on a lot had to share the same foundation height. Following the patch, buildings can now have differing foundation heights, but there must be at least one tile of space between them.

Patch 81 introduced a stilted foundation that allows for construction over water.

Platforms
Patch 103 added the ability to create split-level foundations using platforms. When selecting a room, a second set of arrows will appear in the menu above, which allows the player to raise or lower the floor independently from the foundation. Unlike foundations, two platforms of different heights can be placed directly next to each other, provided they share the same foundation height. Platforms that differ in height by only one "step" can be walked across as-is, but any greater difference requires stairs.

If the ceiling above a room is not removed, a particularly high platform can be used to create an area that only children, toddlers, or pets can access.