Between which two layers should the structural layer(s) be defined when creating a new wall type?

In Revit, the structural layers of a wall are defined to provide the building with necessary support and stability. The core boundary layers are specifically designated for the wall's primary structural (load-bearing) elements. When creating a new wall type, the correct placement of these structural layers is crucial for accurately representing the wall's properties and performance.

Defining the structural layers between the core boundaries ensures that the walls are properly recognized as load-bearing elements within the software. The core is considered the critical structural component, and by placing the structural layers between the two core boundaries, you indicate that they are essential for the wall's intended structural function. This setup allows Revit to analyze and understand the wall's load-bearing capabilities accurately, which is vital for both design and documentation purposes.

The other choices refer to layers that do not typically encapsulate the structural integrity of the wall. For instance, layers like finishes and membranes are oriented more towards aesthetic and environmental factors rather than the structural properties that are relevant when defining a wall's core. Therefore, the placement of structural elements is critical between core boundaries to maintain proper wall function and structural analysis within the Revit environment.