Anchor Points

Anchor Points


A Monolithic Anchor Point Provides Safety

Working atop a Monolithic Dome

Tasks such as cleaning, repairing, painting or covering the outside of a Monolithic Dome often means workers must climb to the dome’s top and move along its curved roof. How do you do that safely?

Over the years, various methods have been developed. For example, some dome tops have air vents or other projections to which workers can tie themselves. For a dome with a smooth surface, a bridle of ropes can be spread over the dome’s top; workers attach themselves to the center of the bridle.

A Better Way

But for working atop any Monolithic Dome, a correctly installed, permanently set Monolithic Anchor Point is the simplest and most secure.

The Monolithic Anchor Point includes a steel plate that is 3/16" thick and 12" square. Each of the plate’s corners has a 7/16" hole. At its center, the plate has a steel pipe with a 2" diameter. That pipe is topped by a steel disk with a 4" diameter. Four 3/8" steel wedge foot anchors complete the package.

The anchor point’s steel plate is permanently bolted to the concrete at the dome’s summit. Workers use it by harnessing themselves with tie ropes that stretch between the workers and the anchor point. Ropes must be snug, so they cannot be pulled over the disk topping the anchor point’s pipe.

Note: The Monolithic Anchor Point must be installed properly and used only with safety equipment.

Installing the Monolithic Anchor Point

  1. Set the Anchor Point’s steel plate on top of the dome.
  2. Through each of the plate’s corner hole, drill a 3/8" hole through the Airform and polyurethane foam, down to the level of the concrete.
  3. Remove the plate and measure that drilled distance.
  4. Using a concrete drill, extend the holes by drilling into the concrete for approximately another 2 inches. Generally, domes have 3 inches of foam and 2 inches of concrete. Do not drill deeper than 2" into concrete.
  5. Put caulking, preferably NP1, around and into each hole.
  6. Fit the anchor point properly over the holes and carefully set and drive in the anchor bolts. Tighten nuts and washers in place. After the anchor point sets, tie ropes can be attached.

The Monolithic Anchor Point comes with four, 3/8" wedge foot anchors. Depending on the foam’s thickness, they will generally be all that’s needed. If the foam is too thick or too thin, longer or shorter bolts may be used. Excess length of the anchor bolt can be trimmed either before or after setting.

Owners can spray an anchor point with a dull silver paint or a color that blends with their dome. It would be good to protect the nuts and tops of the anchor bolts by paint or caulking.

Note: We first presented this article in November 2007.

Diagram

Diagram <cite class='credit'>(Kasey Montgomery)</cite>