The minimum height of a parapet above any wall anchor shall be 12 inches 305 mm.
Roof parapet height code.
The minimum height of a parapet wall above the roof surface is 30 inches.
If a reinforced concrete beam is provided at the top of the wall the minimum height above the wall anchor may be 6 inches 152 mm.
Unfortunately many buildings get close to this height without quite meeting the height required by osha to provide fall protection.
Parapet corrective work must be performed in conjunction with the installation of tension roof anchors.
Buildings greater than 22 feet 6706 mm in height with roof slopes less than 2 4 units vertical in 12 units horizontal 20 percent slope shall be provided with a parapet railing fence or combination thereof not less than 42 inches 1067 mm in height.
2015 ibc code commentary.
Parapets are a combination of wall and roof pressures.
1 every building constructed 3 stories or 36 feet or more in height shall have roof tie backs or other permanent devices installed at the roof level for the purpose of securing or tying back suspended scaffold hooks or clamps and safety lines.