Math Safety for Roofing

When assessing proper fall protection in relation to the roof you are working on how do you ensure that you will be safeguarded from injury?

Some mechanisms to consider prior to suiting up in your harness would be:

  • Is the roof sloped or flat?
  • Where is the best anchorage point- what type of anchorage will you use or install?
  • Will you be utilizing a gravity line with a 3-foot lanyard?
  • Will you be using a retractable lifeline?
  • Does the roof have a parapet?

Once these questions are answered and you have done a thorough inspection to ensure that the harness is in good working order calculate the height of the potential fall by starting at your feet, measure the length of the lanyard and add 3.5 feet.
Falls are the number 2 cause of death on the job according to the Bureau of Labor Statistics. OSHA indicates that fall protection is required at elevations over four feet in general industry, five feet in shipyards, six feet in construction and eight feet in longshoring operations. Fall exposure is calculated from the distance of where you are standing at elevation to the level below. Your fall protection calculation is based upon where your anchorage is located.

How can you calculate the fall arrest distance?

  1. Total fall distance = Length of the lanyard + Height of back D-ring – Height of the anchor
  2. Total fall distance =free fall distance + deceleration distance (shock absorber) + D-ring slide
  3. Minimal required fall clearance = total fall distance + safety distance factory + height of suspended worker (between he feet and D-ring)
  4. Add the safety factor before the nearest obstruction

See the diagram for further instructions.

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