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The top of the riser may be connected to the bottom of the tread by angle-blocks glued to the concealed (back) side of both surfaces with screws added to reinforce the joint. The bottom of the riser is attached to the back of the tread with screws (see Figure 142) or the top of the riser is tongued into the front of the tread and the back of the tread is tongued into the bottom of the next riser (see Figure 142). The wall stringer is screwed behind the treads and risers to the wall. If the outside stringer is an open stringer, it may be cut out to fit the risers and treads. The edges of the risers are mitred with the corresponding edges of the stringer, and the
leading edge of the tread may be returned on its outside edge along the face of the stringer (see Figure 142).
Basement Stairs Closed risers are safer but open risers may be used for basement stairs (see Figure 143).
Exterior Stairs Exterior stairs can be wood or concrete. Concrete stairs with more than two risers must be supported on piers or cantilevered from the foundation wall. The dimensions of risers and treads for exterior stairs are the same as for interior stairs.
143 Basement stairs
Ploughed stringer stair tread leading edge (nosing) slightly chamfered ploughed stringer Cut-out stringer stair tread (supported on cut-out) cut-out stringer Cut-out stringer with an attached finish member 25 mm (1 in.) thick finished member on outside of stringer stair tread (supported on cut-out) cut-out stringer