Paul speaks of what builders usually do when constructing a building to describe what the teachers in Corinth are actually doing. Builders usually only use gold, silver, or precious stones as decorations on buildings.
The building materials used to build a new building are being compared to the spiritual values used to build a person's behavior and activities during his lifetime. AT: "Whether a person builds with valuable materials that will last or with cheap materials that burn easily" (See: [[rc://en/ta/man/translate/figs-metaphor]])