What is the name of the unit placed over an opening in a wall?

The unit placed over an opening in a wall is known as a lintel. A lintel is a horizontal structural element that spans the opening, such as a door or window, and is crucial for distributing the weight of the structure above it. By transferring loads away from the opening, the lintel plays a vital role in maintaining the stability and integrity of the wall. It is typically made from materials strong enough to support the weight, such as wood, steel, or reinforced concrete.

In masonry construction, ensuring that the lintel is appropriately sized and installed is essential to prevent structural problems, such as cracking or sagging of the wall. Other units like beams and headers also serve structural purposes, but they are used differently and may not specifically refer to the unit that spans openings like a lintel does. Arches, while capable of spanning openings as well, function differently by distributing loads in a curved shape rather than as a straight horizontal element.