Trim used in an interior (re-entrant) corner application can be vulnerable. Vegetation is typically planted in this location, and debris can also accumulate there. If a fire starts in this location, flame spread on combustible trim can be greater because of the proximity of the two adjacent surfaces ("re-radiating surfaces"). Particularly if you install noncombustible or ignition-resistant siding, you should install trim with a comparable fire-performance rating. Consider installing noncombustible rock or gravel mulch at interior corners.