In stair design, what does the term 'nosing' refer to?

Nosing refers to the protruding edge of the tread in a stair design. This is an important feature because it serves several functions: it provides a surface for the foot to land on when ascending or descending the stairs, it adds to the visual appeal of the stair design, and it helps to enhance safety by making the edge of the tread more visible, thereby reducing the chances of missteps. The nosing can also be designed to be rounded or square, depending on aesthetic preferences and building codes. Understanding this term is essential for anyone involved in carpentry and stair construction, as it impacts both the functionality and safety of the staircase.