Foundation and Walls
Start with the floor tool when it comes to designing your Sim's home. The tool allows you to lay down a large area of floor covering, which you can use to plan out the shape and size of your entire home. Once the floor plan is to your liking, switch over to the wall tool and set the tool to create an entire room. Erect the walls of your home, making sure that there are distinctions between the different rooms in your house. Without interior walls, Sims have no privacy and game play will be difficult.
Windows and Doors
Once you have the general shape of your house intact you can start adding doors and windows. Switch to the doors tool and select a door within your budget. Place it on an unobstructed wall to create a door between the two sides. When placing doors, be aware of the amount of space you have. The main doorway of your Sim's home should have plenty of space for Sims to enter and exit. Use the window tool to add light into your Sim's home by placing windows on exterior walls.
Designing Your Home
The building tools have several features that let you customize the look of your home. Use the wallpaper tool to add color to your interior and exterior walls. Roofing in "The Sims 2" is free, so select whichever roof style you like from the roofing menu. The landscaping and water tools allow you to add outdoor items to your lot, while the flooring tool can be used to create backyard patios or walkways. Use the fireplace tool to add a fireplace to any exterior wall.
Multi-Leveled Homes
Your Sim home can have multiple levels as long as the upper levels are supported. Use the stairs tool to add a staircase to begin working on a second level. You can add floor tiles and walls to a second-level room in any space that is supported by the structure below. Purchase columns using the column tool to build on areas that are not supported by the ground-floor structure. The foundation tool is used to create homes that are raised above the ground. Create a foundation area and then place floor and wall tiles on top.