Wall

Walls are part of buildings, and can be added or removed in Build Mode. Walls define rooms, and keep the inside in and the outside out—which is particularly important with The Sims 2: Seasons and The Sims 3: Seasons. Some items, such as paintings, toilets, some sinks, fire and burglar alarms need to be placed against walls. Walls can also be built diagonally. Diagonal walls can give a house more interesting shapes, but it may not be possible to place some objects on or against them. In The Sims 2, The Sims 3 and The Sims 4, windows and doors can be placed on diagonal walls, which was not possible in The Sims. In The Sims 2, a Octagonal Room tool is offered to quickly build a enclosed octagonal room of 3x3, which from that size onward can be expanded or contracted with the and  keys respectively.

Walls provide privacy between areas, which means that Sims in a room surrounded by walls cannot be seen by others outside of the room. Walls also block sound, so a stereo that is on will not be heard by Sims that are in another room.

The Sims 2 allows either 2000 or 2100 wall segments per lot before the game will not allow a player to add any more - half-walls and fences are not included in this limit, however the game will not allow a player to add half-walls once the limit has been reached (though it is possible to add additional half-walls by erasing a single wall segment, placing half-walls, then replacing the wall). This limit has either been substantially increased or eliminated altogether in The Sims 3, though the upper limit (if any) is unknown.

Walls can be covered by paint, wallpaper, brick, stone, wood panels and siding, etc. to increase the mood of Sims. In The Sims 3, walls that are not covered will give Sims negative moodlets; in earlier games, uncovered walls will reduce the Room/Environment score.

In The Sims 4 walls have three different heights. If a walls height is changed, every wall in the story will change to that height. However, changing wall heights does not affect all stories on the lot. For example, the first story can have the shortest height option, while the second story can have the tallest option.

Half walls
Half walls are a special kind of wall, introduced in The Sims 2: Nightlife, Patch 17 of The Sims 3 and Patch 21 of The Sims 4. Half Walls are comparable in height to fences or come in five different sizes, ranging from short to very tall. They are completely solid, and can be painted just like a full wall, but only use the bottom part of the wall paint. Its covered top also have different colors in The Sims 2 and can be recolored using Create a Style in The Sims 3. Fireplaces, doors and windows, and other wall objects cannot be placed on half walls, but fence post lights can be put on the posts of the half-walls. There are different kinds of half-walls that have different tops, designs on the tops and colors.

Half walls act similarly to fences. Sims cannot walk over or through half walls. In The Sims 4, they can view and converse with each other over the wall.

In The Sims 4, there are 7 half wall heights.
 * Tall Half Wall - Tall Wall
 * Tall Half Wall - Medium Wall
 * Tall Half Wall - Short Wall
 * Medium Half Wall - Tall Wall
 * Medium Half Wall - Medium Wall
 * Medium Half Wall - Short Wall
 * Short Half Wall

Wall trim
The Sims 4 allows players to add wall trims to both full- and half-walls. Small objects such as plates and toys can be placed on the half wall trims. Placing wall trims is free.

There are 8 wall trims in the base game: Basic, Basic Stone, Basic Wood, Basic Crown, Basic Stone Crown, Basic Wood Crown, Stone, Wood. And 3 from content packs: Slatted, Glass , and Glass Pane

Six full-wall trims are included:
 * Dentil Exterior (§16)
 * Stepped Exterior (§14)
 * Jutting Exterior (§8)
 * Simple Exterior (§4)