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recognized industry practices. Fabricate for waterproof and weather-resistant performance,with <br /> expansion provisions for running work, su�cient to permanently prevent leakage,damage,or deterioration <br /> of the work. Form work to fit substrates. Comply with material manufacturer instructions and <br /> recommendations for forming material. Form exposed sheet metal work without excessive oil-canning, <br /> buckling,and tool marks,true to line and levels indicated,with exposed edges folded back to form hetns. <br /> B. Seams: Fabricate nonmoving seams in sheet metal with flat-lock seams. For metal other <br /> than aluminum,tin edges to be seamed,form seams,and solder. Form aluminum seams with epoary seam <br /> sealer. <br /> C. Expansion Provisions: Where lapped or bayonet-type expansion provisions in work <br /> cannot be used or would not be sufficiently water/weatherproof,form expansion joints of intermeshing <br /> hooked flanges,not less than 1 inch deep,filled with mastic sealant(concealed within joints). <br /> D. Sealant Joints: Where movable,non-expansion type joints are indicated or required for <br /> proper performance of work,form metal to provide for proper installation of elastomeric sealant, in <br /> compliance with SMACNA standazds. <br /> E. Separations: Provide for separation of ineta.l from non-compatible metal or corrosive <br /> substrates by coating concealed surfaces at locations of contact,with bituminous coating or other permanent <br /> separation as recommended by manufacturer/fabricator. <br /> F. Aluminum Extrusion Units: Fabricate extruded aluminum running units with formed or <br /> extruded aluminum joint covers for installation behind main members where possible. Fabricate mitered and <br /> welded corner units. <br /> G. Shop Finish,Rain Dra.inage: Provide mauufacturer's standard baked-0n white acrylic <br /> shop finish on sheet metal rain drainage units(gutters,downspouts,and similaz exposed units); 1.0-mil dry <br /> film thickness. <br /> H. Manufacturers: Subject to compliance with requirements <br /> PART 3-EXECUTION <br /> 3.1 INSTALLATION REQUIREMENTS <br /> A. General: Except as otherwise indicated,comply with manufacturer's installation <br /> instructions and recommendations and with SMACNA"Architectur�tl Sheet Metal Manual."Anchor units of <br /> work securely in place by methods indicated,providing for thermal expansion of inetal units;conceal <br /> fasteners where possible,and set units true to line and level as indicated Install work with laps,joints,and <br /> seams that will be permanently watertight and weatherproof. <br /> B. Underlayment: Where stainless steel or aluminum is to be installed directly on cementitious or wood <br /> substrates, install a slip sheet of red rosin paper and a course of polyethylene underlayment <br /> C. Bed flanges of work in a thick coat of bituminous roofing cement where required for <br /> waterproof performance. <br /> 3.2 CLEANING AND PROTECTION <br /> A. Clean exposed metal surfaces,removing substances that might cause corrosion of inetal <br /> or deterioration of finishes. <br /> Page 3 of 4 <br />