Articles February 28, 2016

Up on the Roof and Beneath a New Tower’s Safety Net

Source: San Francisco Chronicle

By John King, Chronicle Architecture Critic

Large construction projects often are accompanied by scaffolds and cranes. Now here’s a local first: two layers of massive netting draped across metal claws 90 feet in the air, above a three-story brick building from 1907.

A historic structure that, oh yes, has a child care center’s playground on the roof.

The “glove” and its elaborate support system were designed by Level 10 Construction, the general contractor for 181 Fremont St. — a fast-climbing structure that is about one-third of its eventual height of 745 feet. The newcomer begins just 24 feet away from its diminutive masonry neighbor, home to Town Hall restaurant as well as, on the third floor, the Fremont Street campus of Marin Day Schools.

The interwoven fabric net is strong enough to catch anything that might fly off the rising structure, from tape measures and cell phones to wrenches and more.

As for the six angled “claws,” they’re assembled from aluminum beams reinforced with structural plywood. They then are attached to girders perched on a five-story scaffold and tied back to 181 Fremont for lateral support.

Before the net was raised into place, Level 10 dropped 400-pound bags of concrete into it from high altitudes with no problem. A steel beam would be another story, but Chris Wilcox, Level 10’s superintendent, says they never pass above the neighbor’s roof while being hauled aloft.

“Parents have been nervous, but Level 10 has been fantastic — very proactive,” says Elizabeth Chrisman, director of the child care facility. And the 32 preschoolers? Guess. “The children love it, every part of it. They wave at the construction workers and things like that.”

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