Frank Lovece in Building Operations on December 24, 2018
In addition to rappellers on ropes and bucket trucks on telescoping arms, there’s a third alternative to conventional scaffold drops when performing a mandatory building facade inspections: drones.
A drone inspection, like binocular views, can be used to pinpoint problems. They’re of particular use, says Eric Vonderhyde, a principal at Bertolini Architectural Works, on buildings that are ornate, with hard-to-reach, hard-to-see areas. But arranging a drone inspection might involve jumping through more bureaucratic hoops than your board can tolerate.
According to Jim Peters of the Federal Aviation Administration (FAA), “With the exception of lower Manhattan, the northern edge of the Bronx, and the western half of Brooklyn, most of these boroughs are within the LaGuardia or John F. Kennedy airports’ Class B airspace. There is also a sliver of Staten Island on the northwest side that is in Class B airspace of Newark airport. Anyone flying an unmanned aircraft system or drone in these areas must have clearance from the appropriate FAA facility, such as the airport’s control tower, prior to flying in the area, and they must notify any airports that are within five miles.” Boards that hire engineers who use drones for inspection purposes should ensure that the drone operator has received a waiver allowing him or her to fly in controlled airspace. This process can take up to 90 days.
“However,” says Peters, “even in the excluded areas, other airspace operating rules may apply,” such as a New York City regulation that “prohibits aircraft from taking off and landing in the five boroughs, except at public and private airports, heliports, seaplane bases, and in emergencies.”
Drones also do not fulfill the “hands-on” inspection required by the Department of Buildings, which means that any defects that are discovered by a drone must be physically examined by a certified human inspector to ascertain the type and extent of the damage. In addition to using drone video to pick a representative sample of a facade, an engineer or architect can use those images to help prepare highly accurate bid specifications for any repair work that might be needed.
And on the horizon? “It’s still cost-prohibitive, but we’re looking at laser scanning,” says Vonderhyde. “That generates a very accurate 3-D image of buildings, depending on the equipment, down to 1/64th of an inch. You can actively monitor cracks and defects by going back and scanning every so often.” The scan is accurate enough to recognize if a crack grows half an inch.
“We’ve used it on very ornate buildings – we’ve mapped where all the stones are, the terra-cotta units, joints,” adds Vonderhyde, who notes that it is not practical yet for most buildings because a scanner costs $75,000 to $100,000, and the images it takes aren’t 3-D. Rendering it in 3-D requires a trained user to translate that information into a drawing, which can cost around $15,000. “We’re a decade away from this being used more often,” says Vonderhyde. People said the same thing about costly solar panels a decade ago. And look where we are today.
In the meantime, facade inspections performed by rappellers or from bucket trucks can sometimes be more efficient and less expensive than inspections from conventional scaffolds. In the end, scaffolds still have their place. But thanks to the array of affordable alternatives, that place doesn’t have to be your building.
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