In commercial construction projects in Australia, the term "door head" refers to the uppermost horizontal component of a door frame. It is the structural element that spans the top of the door opening and supports the weight above the door. The door head is an essential part of the door assembly, providing stability and ensuring that the door functions correctly.

In more detail:

1. Structural Support: The door head helps to distribute the load from the wall or structure above the door opening, preventing any sagging or deformation of the door frame.

2. Alignment: It ensures that the door frame remains square and true, which is crucial for the proper operation of the door. Misalignment can lead to issues with the door closing and latching properly.

3. Aesthetic Integration: The door head often integrates with the surrounding architectural elements, contributing to the overall aesthetic of the space. In commercial settings, this can include various finishes and materials to match the design intent.

4. Fire and Safety Compliance: In many commercial buildings, door heads, along with the rest of the door assembly, must comply with fire safety regulations. This can include the use of fire-rated materials and construction techniques to prevent the spread of fire and smoke.