299 PARK AVENUE

Concrete Restoration

299 Park Avenue, New York, NY  10007

The 42-story skyscraper at 299 Park Avenue was designed with a ‘curtain wall system,” consisting of numerous windows framed by aluminum mullions. As a result, regular cleaning of the hundreds of windows and periodic façade maintenance is a necessity. The building’s concrete rooftop runway, designed to allow the window-washing apparatus to move on steel rails around the building’s perimeter, provides access to all parts of the exterior façade from a swing stage suspended from the machine. Approximately 30 percent of the runway is suspended above a series of heat-exchanger units with huge fans that cool the building and continuously blow warm and damp air at the underside of the runway.

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Over time, moisture penetrated the concrete fireproofing, causing the imbedded structural steel to rust, which resulted in severely cracked and delaminated concrete. This caused a safety hazard from falling pieces of concrete and diminished fireproofing of the I-beam steel structure. Seaboard Weatherproofing & Restoration was brought in to perform structural concrete repair, concrete restoration and coating of all concrete surfaces with a long-lasting waterproof membrane.

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On the top side of the track, the Seaboard crew removed the existing, failed weatherproofing coating and excavated defective areas. Crew members scraped and painted rusted steel rails, performed specialized repairs on the railing around the pitch pockets, restored the concrete surface, installed flashing and applied new, long-lasting weatherproof coatings. The underside required removal of defective concrete around the steel I-beams followed by the welding and repairing of deteriorated steel. For large section repairs, concrete was poured into a form; for smaller or difficult to access repairs, special repair mortar was hand-troweled in multiple layers to rebuild the concrete encasement. After curing, the concrete was finished with a long-life coating to help protect against moisture from the air conditioning condensers as well as from seasonal weather cycles.

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Concrete work can be performed only in temperate, dry weather, so the Seaboard crew was forced to undertake repairs as the building’s air conditioning system was running and blowing hot air into the work site. To protect its work from the continuously flow of humid condenser air, Seaboard erected enclosures to keep the concrete dry and allow it to cure properly.