See photos of tread thicknesses here.
Cove is an important part of the structure of the stairs. Like a glue block, the cove supports the tread and riser joinery. If no cove is selected, this requires additional measures underneath the stair to ensure proper strength and stability. Below are some of the most common tread nose and cove combinations.
Upgrade to a waterfall stair — a term that refers to the tread nose being flush with the riser. This labor-intensive style requires the talents of highly skilled craftsmen.