On the newer framing squares there are degree conversions for different roof framing plan pdf and fractional equivalents. Likewise, mortises and tenons were traditionally one and a half inches wide when working in hardwoods, explaining the width of the tongue. This allowed for quick layouts of mortise and tenon joints when working both hard and softwoods.
Stairs usually consist of three components. The stringer is the structural member that carries the load of the staircase, the tread is the horizontal part that is stepped on, and the riser board is the vertical part which runs the width of the structure. There are many types of stairs: open, closed, fully housed, winding, and so on, to mention a few of them. Laying out a staircase requires rudimentary math. There are numerous building codes to which staircases must conform. In an open area the designer can incorporate a more desirable staircase.
In a confined area this becomes more challenging. In most staircases there is one more rise than there are treads. Note that the stringer will rest partially on the horizontal surface. A framing square is placed on the lumber so that the desired rise and tread marks meet the edge of the board.