Fall Protection

Safety gear is only as safe as your setup

I’ve heard stories of construction workers who were seriously injured while wearing a harness and hooked up to an anchor, and the reason was a lack of proper setup. To be safe in case of a fall, you have to set up your fall-protection system based on the specifics of the job, including the area being worked on, number of anchors, distance to the ground, and any potential for swinging.

Mapping out anchor points

When setting up for fall restraint or arrest, many builders either use too few anchors, or, not wanting to take the time to calculate anchor positions, space them every 8 ft. along the ridge and often end up with far more than necessary.

The best way to determine how many anchors are required and where they need to be placed is to grab a compass and the scaled building plans.

Place the pivot point of the compass on the ridge (A) and extend the pencil point so the widest part of its arc is about 2 ft. beyond the eave edge, and it also contacts the lower corner of the roof.

Then, without changing the setting on the compass, place the two points so the pencil is on the spot where the first arc crosses the eave (B) and the pivot point is on the ridge (C), then scribe a second arc. Repeat across the entire roof.

Knowing when to switch anchors

Planning the overlap of different anchor points on paper is one thing, but deciding when to switch anchors while on the actual roof is another. Here’s the trick: Take your height, say 6 ft. (or 72 in.), and subtract the distance from the working surface to the D-ring on your harness, which we’ll say is 52 in.

72 in. – 52 in. = 20 in.

Now, hook your lifeline to the first anchor and walk from the ridge down to the eave, keeping the line taut. From this taut position, measure 20 in. beyond the rope grab and tie a knot in the lifeline.

While working, when the rope grab hits the limiting knot, you have found the limit of your safe working angle and it’s time to unclip from the first anchor point and clip into the second anchor point. Without that limiting knot, you could just keep feeding out more line and put yourself at risk of exceeding the free-fall distance if you go over the edge.

Factoring your fall distance

We prefer to stay in fall restraint whenever possible, but anytime you are relying on fall-protection equipment for fall arrest you have to factor in the length of the fall. We’re always mindful of the truism, “You want more air than rope.” Here’s how to calculate the potential fall distance.

Typically the below calculations will come out to about 18-1⁄2 ft., which is a good rule of thumb. But even when working on buildings where you have more than 18-1⁄2 ft. of distance from roof edge to the ground, you will be limited by the allowable free-fall distance, which is 6 ft.

Safety check

Each time a harness is donned, it needs to be inspected for wear. Many harnesses have red thread woven into the webbing—if you can see it, remember, “Red is dead,” and take the harness out of service. Many manufacturers also have expiration dates on the tag. If the harness looks good but is past the expiration date, take it out of service and destroy it.

Make sure that in addition to inspecting your harness, you store it properly. Moisture and mold can damage the webbing. Dirt should be wiped off with a damp sponge and warm soapy water, and it should be stored out of direct sunlight. I like to hang mine by the rear D-ring to let it dry.