Covering the Washington Monument
In the late 1990s, the Washington Monument was surrounded by 37 linear miles of aluminum-tubing scaffolding so that workers could restore the stone structure. Today, scaffolding is in place again as part of a $15 million project to repair damage sustained during the 2011 earthquake. Decorative lighting and fabric will also be installed. The restoration will take 12 to 18 months, with the monument scheduled to reopen in spring 2014. See how damage will be repaired or read related article.
The scaffolding design is identical to the one architect Michael Graves designed for the monument’s restoration that was completed thirteen years ago.
Weight distribution — Covering an area of
3.2 acres, the 500-ton scaffolding system is able to sustain 450,000 pounds. Special trusses above the east security entrance and the west bunkers redirect the scaffolding weight over the open spaces. Concrete foundation pads distribute weight evenly.
Tapering — To mirror the tapered shape of
the monument, engineers had to adjust the dimensions of the two outer sections of scaffolding on each face every 6 feet.
The scaffolding does not touch the stones
in the pyramidion portion of the monument.
Four motorized work decks on each face will hang from the inside of the scaffold-
ing in the 3-foot space between the scaffold-
ing and monument. The pyramidion will have adjustable, non-
motorized work decks. As many as 20 people
may be working on the decks at one time.
Motorized work decks can extend down the height of the monument but must be posi-
tioned with at least one platform level between them for safety.
Elevator and stairs
The elevator was built outside the scaffolding on the south face. Stairs are located inside
Engineers used corner and center braces placed every 26 vertical feet. The braces, together with a steel cable, help “cinch” the scaffolding in place around the monument. Brace pads are made of wood, one side of which is coated with a type of plastic foam that will not mar the stone. The pressure exerted
on the monument face by each pad is
100 pounds per square inch.
Each scaffolding leg is embedded in a concrete pad, pitched at a 1 degree angle, bolted in place and sealed with grout. More than a dozen concrete foundation pads were installed to distribute the scaffolding weight evenly, and some are designed to bear more weight in the front than in the back to accommodate the tapered design. Part of the plaza was removed to install concrete pads.
SOURCES: National Park Service, Universal Builders Supply Inc. PHOTO by The Washington Post