Openings — what do we call the exposed vertical surfaces at right angles to a door/window frame? In door and window detailing, the portions of the wall surface that lie perpendicular (at right angles) to the frame and become exposed when an opening is formed are known as what?

Introduction / Context:
Clear terminology helps in specifying finishes, trims, and measurements around openings. Different faces around a door or window have specific names that inform plastering, painting, or cladding instructions as well as hardware placement and airtightness details.

Given Data / Assumptions:

• Wall opening with a door or window frame fitted.
• Surfaces considered are the exposed wall returns at 90 degrees to the plane of the frame.
• Conventional building terminology is used.

Concept / Approach:

The vertical members of the frame itself are called jambs, while the structural horizontal over the opening is a lintel. The horizontal underside of an element is a soffit (e.g., soffit of a lintel). The exposed return surfaces of the wall that are perpendicular to the frame are called reveals. Reveals often receive plaster beads, damp-proofing details, or window tapes to ensure a neat and sealed edge.

Step-by-Step Solution:

Verification / Alternative check:

Trade specifications for plastering and window installation list “reveal plaster”, “reveal beads”, confirming standard usage of the term.

Why Other Options Are Wrong:

• (a) Jambs are part of the frame, not the wall returns.
• (b) Lintel is a horizontal support, unrelated to vertical returns.
• (d) Soffit is the underside of an element, not the vertical return surface.

Common Pitfalls:

• Calling the frame jamb surface a “reveal”; keep frame vs. wall distinct.
• Ignoring airtightness detailing at reveals leading to drafts and moisture issues.

Final Answer:

Reveals.