| Value | Category |
|---|---|
| 1 | Wood |
| 2 | Sheet metal |
| 3 | Adobe or clay |
| 4 | Semi-permanent (earthen bricks with joints, cement, or cement-covered adobe) |
| 5 | Geopolymer concrete (earthen brick, mixed with cement, made by a machine) |
| 6 | Hard (stone, cement bricks, concrete, or similar) |
| 7 | Other |
| 8 | Unknown |
| 9 | NIU (not in universe) |