Which component is NOT part of a vegetated roof assembly?

A vegetated roof assembly typically includes several essential components that work together to create a sustainable roofing solution. The retention layer is crucial as it helps hold moisture in place for the plants, providing necessary water while preventing excess runoff. The waterproofing membrane is fundamental to protecting the underlying structure from water infiltration, ensuring that the roof remains leak-free. Insulation is also a key component, as it helps regulate temperature and improve the energy efficiency of the building.

Crown molding, on the other hand, is a decorative element used in interior design, primarily for finishing the edges where walls meet ceilings. It does not serve any functional purpose in the context of a vegetated roof assembly. Thus, it is appropriately identified as the component that is not part of a vegetated roof system, as it does not contribute to the roof's ecological or structural performance.