Thing's are a little different in Canada... What is the text of the legislation that calls for ASTM F 1637? I assume it defines the application of building codes by construction date, and may optionally apply to older buildings, depending on the extent of a renovation. Lets say a particular building code does apply. What is the text of the code? Does it call for walkways to meet ASTM for residential buildings? ...for other than principal entrances? All of the above notwithstanding, the Standard Practice for Safe Walking Surfaces calls for changes of level greater than 1/2 in. (12 mm) shall be transitioned by means of a ramp or stairway that complies with applicable building codes, regulations, standards, or ordinances, or all of these. The National Building Code of Canada specifies a minimum rise of 125 mm (~5") for residential stairs. However: The 3' area sounds like a landing which cannot be shorter than the width of the stairs, or 860 mm (~34"). If this stair is inside the porch, the minimum risers is 3 Perhaps your codes are similar. Your description sounds like a good application for a 1:12 ramp, about 5 degrees, to replace that first 6' section. Are Americans applying building codes to home inspections (not new construction inspections)? I would consider this informational only... at best, useful if a client were considering renovations.