What is the purpose of bed or crown molding in a box cornice?

The purpose of bed or crown molding in a box cornice is to provide a decorative finish at the intersection of the soffit and the house wall. This molding not only adds an aesthetic appeal by giving a polished look to the transition between two surfaces, but it also serves to neatly cover any gaps or irregularities where the soffit meets the wall. This transition can be visually sensitive, and using molding helps to create a clean appearance that enhances the overall design of the exterior of the building.

Festooning this area with crown molding can also serve practical purposes, such as shielding any joints from direct exposure to moisture and aiding in the prevention of potential damage over time. However, the primary function remains decorative, making the connection more visually pleasing and refined.