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. Concrete for exterior stairs must have a compressive strength of at least 32 MPa (4600 psi) and air entrainment of 5 to 8 per cent. Portions of wood stairs in contact with the ground must be treated with a wood preservative.

Source : Canada Mortgage and Housing Corporation (CMHC)