IRC Building Residential Inspector Practice Exam

The rule focuses on safe clearance around a fireplace opening by tying how far a combustible material can protrude to how far it is from the opening. Combustible material within a specified distance must not project more than 1/8 inch for each inch of distance from the opening. That distance is 12 inches, so at 12 inches away the material may project up to 12 × 1/8 = 1.5 inches. This setup allows a little more protrusion as you move farther away, while keeping items near the opening from overheating or igniting. For context, closer distances have smaller allowable projections, and farther distances allow a bit more, all to maintain safety around the heat source.