Door Openings – What are the vertical faces called that receive the frame? In building terminology, the vertical faces of a door opening (in a wall) that support and receive the door frame members are known as what?

Introduction / Context:
Clear terminology avoids confusion between wall opening components and door shutter parts. The wall provides an opening with finished faces; the frame is fixed into that opening; and the shutter (leaf) is hung on the frame. Each has distinct names used in drawings, measurements, and site instructions.

Given Data / Assumptions:

• We are referring to the wall opening, not the door leaf.
• The door frame (jamb members) is fixed against these faces.
• Conventional masonry or concrete wall construction.

Concept / Approach:

The vertical faces of the wall opening are called jambs. The reveal is the finished side surface of an opening (often including head and jamb returns) but in many site usages, “jamb” specifically denotes the vertical side faces. “Stiles” belong to the shutter (leaf), not the wall opening. “Posts” and “mullions” are different structural or framing members and are not the correct terms for a door opening’s side faces.

Step-by-Step Solution:

Verification / Alternative check:

Architectural glossaries and IS terminology specify “jamb” for vertical sides of openings; frames are secured to jambs with holdfasts/anchors.

Why Other Options Are Wrong:

They refer to other components or are generic terms; “reveal” is sometimes used broadly but the precise term here is “jamb”.

Common Pitfalls:

Confusing jambs with stiles; assuming “post” describes any vertical member irrespective of context.

Final Answer:

Jambs