Mortise Depth — Geometric specification
Category: Geometric specification
Depth at which treads are mortised into the stringer grooves.
The mortise depth is the distance by which treads of a mortised stringer staircase are embedded in the stringer grooves. It is usually between 15 and 20 mm and is crucial for the load transfer: too shallow a mortise weakens the connection; too deep a mortise reduces the remaining stringer cross-section. Together with the tread thickness, the stringer height and the position of the tie rods, the mortise depth forms the basis of structural sizing for a stringer staircase. The groove profile is now almost always machined on CNC processing centres.