Build mode is the main interface for constructing and furnishing houses and lots in The Sims 4. Buy mode, the interface for purchasing house furnishings in previous games, is merged into Build mode. In Build mode, players purchase furniture and appliances for Sims such as televisions, showers, beds, and fridges, with each of them having a set function, ranging from fulfilling a need or raising a skill or simply being decorative. Some locked or hidden items may be unlocked through the progression of career levels or cheats. Players can also construct buildings and design interior layouts from scratch, then save their custom buildings and lots into the in-game library. Entire rooms and buildings can be resized, moved, and duplicated, along with all objects placed within the room. Alternatively, selections of pre-made furnished rooms and buildings are available. Players can build on and customize every lot on the world map, and can only build within the boundaries of each lot. Bodies of water can be constructed, such as decorative fountains, swimming pools, and ponds. Interior construction options include doors, archways, half-walls, wall coverings, and floors.