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JOB AT A GLANCE PROJECT: Rehab of 15 residential buildings with 10,000-square-foot (929 m²) basements damaged by severe flooding from Hurricane Sandy COATINGS CONTRACTOR: Manhattan Concrete Design LLC 385 1st Ave. New York, NY 10010 (646) 476-8376 www.mcdnyc.com SIZE OF CONTRACTOR: 12 employees For the floors, the crew is using a two-part epoxy from Land Science (a division of Regenesis) called Retro-Coat, which helps keep potentially hazardous vapors from coming up through the slab into the air. construction in the 1940s, did not require a vapor barrier. When Manhattan Concrete Design frst arrived on site, the concrete substrate was highly saturated with moisture, and it was cracked and riddled with contaminants. Terefore, Koerner's crew routinely utilized calcium chloride and moisture tests along with visual assessments (i.e., looking for "fsh eyes after pouring the frst layer of epoxy," in his words) while diamond grinding and shot blasting to determine the proper course of action. In some cases, slabs had to be replaced with a vapor barrier installed underneath. "To prepare," Koerner explained, "especially with a lot of corridors and tight areas, we used 7-inch [18 cm] Metabo diamond grinders, shot blasters in larger areas, and HTC planetary grinders to get best floor flatness. When the concrete is a little wavy, we use grinders to get optimum floor flatness and are sure to remove loose debris and prep to manufacturers' specs." On each of the 15 buildings, after prep work is completed, the team utilizes a relatively new product from Land Science (a division of Regenesis) called Retro-Coat. A "standard epoxy," Retro-Coat is applied in two coats at 16 mils (406 microns) per coat using squeegees and then backrolling the foor with 18-inch (46 cm) rollers. Te epoxy is blended in a two-part correct ratio in a slow speed mixer prior to application. Te Retro-Coat also has a rating as a vapor barrier, which is very important given the residential nature of the project. In addition to the fnished foor, the project also includes 12,000 linear feet (3,658 m) of 4-inch (10 cm) seamless cove base around exterior walls. And even more is done to some areas, which are then tiled, depending on their use to the residents. Constant Coordination In terms of safety on this ongoing project, the crew maintains a high level of vigilance given not only the conditions but also the crowded workspace that the Manhattan Concrete Design team has to share. Koerner's crew wears 3M respirators, safety glasses, and refective vests, and they use fagmen for SIZE OF CREW: 10 total crew members, broken up into groups of 3–4 people PRIME CLIENT: Peter Cooper Village 252 First Ave. New York, NY 10009 (888) 767-3175 www.pcvstliving.com SUBSTRATE: Concrete CONDITION OF SUBSTRATE: Severely damaged and warped by flood damage and contaminates SIZE OF JOB: 150,000 square feet (13,935 m²) total DURATION: 15 weeks UNUSUAL FACTORS/CHALLENGES: » Post flood conditions included contaminates from soil » Lack of initial vapor barrier in the building and flooded floors necessitated a new vapor barrier product » Busy work space with other trades and residents required coordination MATERIALS/PROCESSES: » Used 7-inch (18 cm) Metabo diamond grinders and HTC planetary grinders to prepare the floors to manufacturers' specs » Applied two 16-mil (406 microns) coats of Retro-Coat using squeegees and then backrolled the floor with 18-inch (46 cm) rollers » Applied 12,000 linear feet (3,658 m) of 4-inch (10 cm) seamless cove base around exterior walls » Tiled additional areas depending on their use to the residents SAFETY CONSIDERATIONS: » Wore 3M respirators, safety glasses, and reflective vests » Used flagmen for unloading equipment and material into occupied community » Ensured that noise and the off-gassing of materials were kept to a minimum due to residents COATINGSPRO JANUARY 2014 47