Efficient Use of Warning Line Systems - Quicksilver Engineering

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          WARNING LINE SYSTEMS for METAL ROOFS
                                                                                              by Nick Kerber, P.E.
                                                                     Quicksilver Engineering

    Warning line systems offer an easy and economical way to protect workers from falls on low sloped roofs. They set up quickly, cover large areas, and meet OSHA requirements for fall protection. Warning line systems can be used by erectors, metal roofers, and roof restorers for roofing, remodeling, repairs, and as a control line during decking operations.

                         Metal Roof Systems

                  Typical warning line system on a metal roof   Figure 1

The Basics

    Fall Protection is required for workers on decked roofs over 6' high (the trigger height varies in some states). Workers must be protected from falls at roof edges and holes. Federal safety codes allow warning line systems in CFR 1926.502. Low slope roofs and sections with widths less than 50' may be worked with only a safety monitor as fall protection.
    Warning line systems protect workers by roping off a work area with a flagged line at about waist level, and operate on the principle that the line will warn workers when they are dangerously near the edges. They provide a visible warning and a minor physical resistance to constrain workers. Warning lines do not arrest a fall like safety lines or restrain workers like a guardrail. They instead confine workers to an area at least 6' from the fall danger, giving a margin of safety for tripping or stumbling workers.   Workers are allowed to work unrestricted within the work area, avoiding the inefficiency and frustration of fall arrest lifelines. These systems may be used on low sloped roofs (roofs with slopes up to a 4:12 pitch) which includes most structural metal roofs. Warning line systems can protect workers from open holes and skylights and can rope off an access area at an edge. A warning line may serve as a control line to separate a controlled decking zone from decked areas during sheeting operations. Training is easy and they can be used in conjunction with other safety systems.
    A warning line system consists of flagged rope supported by portable stands in a closed perimeter (see fig.1). The line is flagged every 6 feet for high visibility. Work at the roof edge is performed under the supervision of a safety monitor who controls the safety of the work.

Using Warning Line Systems

    Set up of a warning line system is straightforward. A worker sets up stands 6' from the edge of the building with approximately 40' spacing between stands. Where mechanical equipment is to be worked toward an edge, the warning line must be at least 10' from that edge. A flagged warning line is then fastened from stand to stand so that it hangs between 34" and 39"(1 meter) above the roof surface, forming a closed perimeter and securing the area for use (flagline heights for California and Washington state codes presently differ from federal codes). One man can set up a large area in a matter of minutes. At the end of the job, the line is reeled up, and the stands are transported off the deck.

Typical Warning Line Layout

                                                                                            Figure 2

    When loading a roof, the roof spotter can direct loading without being tied off so long as he stays within the work perimeter.
     Where access to the roof edge is necessary, as when loading or unloading exposes an edge, the requirements allow warning lines that properly contain the area and tie it off when not in use. An access area edge is boxed in with four stands; one each on the two sides of the access area at the edge, and one each out from the edge stands on the 6' perimeter (see fig.2). A flagline is tied from the edge to the perimeter for each side, and a removable line is tied between the 2 perimeter stands that is untied during access. During access, workers near the edge are supervised by a safety monitor.   Warning lines are used to provide access walkways from ladders to the work area in the same way.
    If a lift bed truck is used to load a roof, warning lines can be tied from the sides of the truck to the 6' perimeter.

    Warning line systems are used to rope off deck openings by encircling the holes with a warning line 6 feet from their edges.

    Work at the roof edge is done with the system pulled back from the edge and the workers supervised by a safety monitor.   The safety monitor controls the safety of the work. He must be capable of recognizing fall and safety hazards, be close by, be able to get workers attention verbally, and have no other duties that distract his safety function. He wears a safety vest.   Because a safety monitor contributes little to the actual production of the roof, it is common practice to limit the area of the roof edge work to be as small as possible.

    Warning line systems can be used on multistory buildings but do not relieve the responsibility to install perimeter safety cables after the deck is complete.

    In high winds and in inclement weather extra precautions are taken with warning line systems as with other roof equipment and materials. In these conditions, the stands should be secured by weighting them down with sandbags or other dead weight during the day. At the end of the workday, the stands can be knocked down and laid down in place with the line still attached for a quick set up in the morning.

Control Lines

    During the installation of steel decking, warning line systems can be used as a control line to separate unsecured decking areas from the secured areas.

    When workers install roof and deck panels in steel erection, they are exposed to fall hazards at the leading edge and through loose sheets. Federal safety codes allow management of these fall hazards by training panel installers, equipping them with fall protection, and by using control lines to fence off the paneling area from other workers.

    The use of control lines creates a controlled decking zone (CDZ) where panels are installed with special requirements.

   The Codes

     Fall protection for steel roofs and decks is controlled by the steel erection rules (CFR 1926.760-.761) where steel erection occurs (key phrase), and by general fall protection rules (CFR 1926.500-.503) where it does not.
    Fall protection requirements for steel erection varies with deck height and are listed in table 1.
    General fall protection requirements on decks with slopes up to a 4:12 pitch are listed in table 2.

                                                            Table 1

Height	Fall Protection for Steel Erection Outside a CDZ	Fall Protection for Steel Erection Inside a CDZ
0-15'	none	none
15-30'	guardrail systems, safety net systems, fall arrest systems, positioning device systems, or fall restraint systems	none
30'+ or over 2 stories	guardrail systems, safety net systems, fall arrest systems, positioning device systems, or fall restraint systems	guardrail systems, safety net systems, fall arrest systems, positioning device systems, or fall restraint systems

Table 2

Height	Fall Protection
0-6'	none
6'+	guardrail systems, safety net systems, fall arrest systems, positioning device systems, warning line systems, or safety monitors when minimum deck dimension is 50' or less

    The requirements of each of these fall protection systems are lengthy and are found in CFR 1926.502. Briefly:

    Guardrail systems include a complete railing system with a top rail 42" high that can withstand a 200# outward force and a middle rail that can withstand a 150# outward force.

    Safety net systems must be tested by dropping a 400# sandbag 42 inches and when used for edge protection must extend at least 8' out from edges.

    Personal fall arrest systems include body harnesses, a shock absorbing lanyard or retractor that safety limits free falls to 6', and a 5000# anchorage for each man.

    Positioning device systems include body harnesses or body belts, a shock absorbing lanyard or retractor that safely limits free falls to 2', and a 3000# anchorage for each man.

    Warning line systems rope off edges with stands and flaglines 6' from edges and use a safety monitor for work within 6' of the edge.

    Safety monitors are competent, active safety supervisors.

    Controlled decking zones on decks up to 30 feet in height give panel installers the freedom to work unencumbered and without the tripping and tangling hazards of fall arrest lifelines. The rules for the use of a CDZ are outlined in the following insert:

1926.760(c) Controlled Decking Zone (CDZ)

     A controlled decking zone may be established in an area of the structure over 15 and up to 30 feet above a lower level where decking is initially being installed and forms the leading edge of a work area. In each CDZ, the following shall apply:

    (1) Each employee working at the leading edge in a CDZ shall be protected from fall hazards of more than two stories or 30 feet, whichever is less.

    (2) Access to the CDZ shall be limited to only those employees engaged in the leading edge work.

    (3) The boundaries of a CDZ shall be designated and clearly marked. The CDZ shall not be more than 90 feet wide and 90 feet deep from any leading edge. The CDZ shall be marked by the use of control lines or the equivalent. Examples of acceptable procedures for demarcating CDZ's can be found in Appendix D to this subpart.

    (4) Each employee working in a CDZ shall have completed CDZ training in accordance with 1926.761.

    (5) Unsecured decking in a CDZ shall not exceed 3000 square feet.

    (6) Safety deck attachments shall be performed in the CDZ from the leading edge back to the control line and shall have at least two attachments for each metal decking panel.

    (7) Final deck attachments and installation of shear connectors shall not be performed in the CDZ.

Appendix D- Illustration of the Use of Control Lines to Demarcate Controlled Decking Zones (CDZ's): Non mandatory Guidelines for Complying with 1926.760(c)(3)

    (1) When used to control access to areas where leading edge and initial attachment of metal deck and other operations connected with the leading edge work are taking place, the controlled decking zone (CDZ) is defined by a control line or by any other means that restricts access.
          (i) A control line for a CDZ is erected not less than 6 feet nor more than 90 feet from the leading edge.
        (ii) Control lines extend along the entire length of the unprotected or leading edge and are approximately parallel to the unprotected leading edge.
          (iii) Control lines are connected on each side to a guardrail system, wall, stanchion or other suitable anchorage.

    (2) Control lines consist of ropes, wires, tapes, or equivalent materials, and supporting stanchions as follows:
          (i) Each line is rigged and supported in such a way that its lowest point (including sag ) is not less than 39* inches from the walking/working surface and it highest point is not more than 45* inches from the walking/working surface.
         (ii) Each line has a minimum breaking strength of 200 pounds.

* Author's Note: This is a non-mandatory example. Line height may be 39" sagging down to 34" as with warning line systems.

     Several fastening methods are used with the different kinds of panels. Some common panel systems are exposed fastener panels, snap-lock standing seam panels, and field-seamed panels. Field-seamed panels are mechanically seamed in place with either single pass or double pass folders. Roof dimensions and geometry often suggest a best installation sequence.

               Panel Installation 1

Tips

   Flaglines can be easily handled on a reel. The reel eliminates hand coiling the line and the inevitable tangles and knots that comes with hand coiling. If you don't have reels, electrical reels will work well and can be purchased cheaply at your local hardware store. When laying out flaglines, after the line is tied to each stand, kick the stand slightly, to inch it in one direction or another to fine tune the height of the flagline at midspan to near 34" above the roof deck.
    To begin knockdown of the system, reel the flagline up, walking from stand to stand, and use the stands to keep force on the line, which makes reeling quick and easy. Avoid unfastening the flagline from all the stands and reeling loose line.

The Equipment

    Warning line systems that meet the special needs of metal roofs are available. One-piece collapsible stands open quickly from a compact unit, use little space in a truck, and provide easy set up. Rubber pads on the legs of the stands provide skid resistance to the stand on the metal deck, and raise the stands so they bridge standing seams and ribs. The stands set on the flat parts of metal panels and fit the large spectrum of panel contours. The stands knock down swiftly, are light, and durable.

Metal Roof Stand 1

                              Straightforward set up of 1-piece stands.

    Flaglines are generally made from 3/16" rope with flags fastened every 6'. They are required to have a tensile strength of at least 500 pounds. Various kinds of rope are used. An inexpensive polyethylene banner is sold by one manufacturer with a short life of 1 month. Polypropylene lines are fairly cheap, tend to kink and tangle, and last about a year before they lose their strength in the sunlight, weather, and heat. Polyester lines cost a little more, but are kink proof, with excellent sun and weather resistance, and can be expected to last several years.

    Warning line systems provide an efficient, flexible, and economical method of fall protection on metal roofs with the added benefit of giving workers free movement in protected work areas. They reduce the workers' burden. Compliance is easier and OSHA visits are less likely to be confrontational. Warning line systems avoid costly OSHA fines that run in the neighborhood of $2500.

    Nick Kerber has 20 years roofing experience, is a professional engineer, and is president of Quicksilver Engineering, a manufacturer of warning line systems. For questions, or to share safety tips and OSHA experiences, Mr. Kerber can be reached at (541)459-5571.