Single-unit (monolithic) roofing materials applied to flat roofs may seem “safer” to some roof installers, but the job is always at height and subject to many similar hazards and the same safety requirements applicable to work on sloped roofs. Good fall protection measures, personal protective equipment (PPE), and adherence to safe work practices can protect workers from fall hazards.



Roof installers who install, maintain, or repair flat roofs with heights greater than 20 feet or using machinery that must be pulled in reverse, such as felt applicators, need to use fall protection. Fall protection measures may include one or more of the following:


Personal Fall Protection Fall Protection Platforms Scaffold Platforms

Standard guardrails and skirting boards Eave barriers 24-inch high parapets

Where the above fall protection measures are not used, the edges of the flat roof should be marked with yarns of materials and warning lines to notify workers of potential fall hazards using the following guidelines:


Place rows of materials (sheets of roofing material or other materials) not less than 5 feet from the edges of the roof and parallel to the roof line.

Install warning lines no less than 5 feet from roof edges and up to a height of 34 to 45 inches.

Place warning lines and yarns of materials around the perimeter of the roof.

If warning lines and material yarns are used only in the work area, move them as the roof work progresses to provide a permanent warning to workers.

Connect material handling areas, storage areas, and roof access routes, leaving a clear path of two (2) warning lines.

When an access route is not in use, cross a rope, cable, or chain of equal strength to that of the warning line to block entry to the access route from the work area.

Warning lines have specific requirements that include:


Warning line material may be ropes, wires, or similar with a tensile strength of not less than 500 pounds.

Mark warning lines with flags of highly visible material, placed every 6 feet away.

To secure warning lines, use sturdy fixed or portable brackets designed to minimize rollovers or displacement.

Attach and temper warning lines to each support so that they do not slip or create play between supports when pulled.

The above fall protection measures are necessary for workers who operate felt installation machines (or other equipment that must be pulled in reverse) regardless of the possible fall height. An exception to these measures is that the parapet must be at least 36 inches high and perpendicular to the direction of travel. When these fall protection measures are not installed:


Place rows of materials not less than 10 feet, and warning lines not less than 5 feet from the edge of the roof on a route perpendicular to the direction of travel.

If conditions prohibit the use of material yarns, move the warning lines not less than 10 feet from the roof edges on a route perpendicular to the direction of travel.

Never operate equipment that must be pulled in reverse in areas located less than 3 feet from the edge of the roof.

Do not store motorized equipment with an operator’s seat between the warning line and the roof.

Train all workers on the use of the warning line and material yarn system. Instruct workers to work within protected areas. Warning lines and material yarns may not be practical for working on the edge of the roof, on narrow roofs, or on unusually shaped roofs. In these cases, a qualified person should closely supervise work on the roof.


Roofing is dangerous work; do not rely on or ignore the dangers of working on flat roofs even though they may seem safer to you. Follow the safety guidelines described in this document to avoid potentially dangerous or fatal falls when working on flat roofs.