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 an a square area on the terrain. 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. With the Late Night patch of The Sims 3, a new platform tool is introduced. It allows a player to create a flat elevated by a half-inch floor surface for Sims to use. Unlike the foundation tool, it doesn't require stairs. It may or may not create and define contained content on it as within a "room".

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 4
Unlike previous games, foundations can be built and adjusted to any height. Prior to patch 73, all buildings on a lot had to share the same foundation height. Following the patch, buildings that are not connected to each other can have different foundation heights, or not be built on a foundation at all. The foundation height of each building can be adjusted by selecting a room using the foundation height tool and then dragging the widget in the center. If a foundation's height is lowered beneath ground level, it will produce a crater of the equivalent depth. Patch 81 introduced a stilted foundation that allows for construction over water.