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• <br /> • <br /> Backstop NT For Use Beneath Claddings Other Than Dryvit EIFS Specifications DS200 <br /> 1.04 DESCRIPTION <br /> A. General: Dryvit Backstop NT is available in Texture, Smooth and Spray and is a flexible polymer based, <br /> noncementitious, protective coating used as an air/water-resistive barrier when applied over acceptable <br /> exterior substrates. <br /> B. Design Requirements <br /> 1. Acceptable surfaces for Backstop NT include: (Refer to DS300, Backstop NT Application Instructions For <br /> Use Beneath Claddings Other Than Dryvit EIFS for more specific requirements) <br /> a. Exterior grade gypsum sheathing meeting ASTM C 1396 (formerly C 79) requirements for water <br /> resistant core or Type X core at the time of application. <br /> b. Exterior sheathing having a water-resistant core with fiberglass mat facers meeting ASTM C 1177. <br /> c. Exterior fiber reinforced cement or calcium silicate boards. <br /> d.APA Exterior or Exposure 1 Rated Plywood, Grade C-D or better, nominal 1/2 in (12.7 mm) minimum, <br /> installed with the C face out. <br /> e. APA Exterior or Exposure 1 Fire Retardant Treated(FRT)Plywood, Grade C-D or better, nominal <br /> 1/2 in (12.7 mm) minimum, installed with the C face out. <br /> f. APA Exposure 1 Rated Oriented Strand Board(OSB) nominal 1/2 in (12.7 mm), minimum. Note: <br /> Applications over OSB sheathing requires a minimum of 2 coats of Backstop NT—Smooth or <br /> Spray. Backstop NT—Texture is not recommended for the field of wall application over OSB. <br /> g. Unpainted, unsealed concrete and CMU. <br /> 2. Backstop NT is not intended to be used as waterproofing for exterior horizontal surfaces or below grade <br /> applications. <br /> 3. Backstop NT can be exposed to weather up to 180 days to provide sufficient time for installation of the <br /> cladding. Inspect the surface of the Backstop NT for any damage, cracks,voids or other detrimental <br /> conditions and repair prior to installation of the cladding. <br /> 4. Deflections of the substrate systems shall not exceed 1/240 times the span. <br /> 4- <br /> 3 <br />