| Name | Description | Constraint |
| Foundation | The base of all buildings | Inside terrain |
| Wall | Vertical walls | with foundation or level in their cell |
| Wall opened | Vertical walls with a hole in them for doors, windows, etc | with foundation or level in their cell |
| Level | Floors above ground | on walls, or snapped to other levels if not too far from |
| Roof | Topmost part of buildings | On walls, with a maximum width and length |