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A. Gypsum cementitious underlayment:USG.LEVELROCK <br /> B. Mineral Aggregate: ASTM C 332,Group I. <br /> C. Sand Aggregate: ASTM C 33. <br /> D. Water: Clean,potable. <br /> E. Subfloor Primer or bonding agent:USG.LEVELROCK underlayment Primer <br /> 2.2 DESIGN 1VIIX <br /> A. General: Design lightweight Gyp insulating concrete mix shall be in strict accordance with <br /> Manufactures recommendations <br /> Mi�c design shall be proportioned to provide an average(three cube)compressive strength of 2,500 psi or <br /> greater with a density of 115 pounds per cubic ft. No cube sample taken for testing shall be less than <br /> 2,000 psi. <br /> PART 3-EXECUTION <br /> 3.1 PREPARATION <br /> 1. Condition and cleaning of subfloor: Subfloor shall be clean of mud,grease,and all other <br /> contaminating debris before installation begins. Sub strates must be clean and dry. Set <br /> temporary dams at max of 8' <br /> 2. Leak prevention: Fill Cracks and voids in subfloor with insulation. Caulk or patch to stop <br /> any potential leakage of material. <br /> 3. Priming of subfloor:Prime the subfloor using the LEVELROCK subfloor primer. <br /> Priming instructions vary according to the type of substrate. Multiple coats of primer may <br /> be necessary. Care should be taken to protect radiant heating coils during application of primer. <br /> 4. Building Joints: Allow joints to continue throughout the underlayment at the same width as the <br /> building joints. <br /> 3.2 PLACEMENT/APPLICATION <br /> A. Application:Place underlayment%s"min thickness over type of radiant tubes. This will require a <br /> total thickness of 1-1/2"of gypsum cementitious underlayment. It is recommended that the installation be <br /> made in two applications. The first application should be poured 1/8"minium over the top surface of the <br /> radiant heat tube. The second application should be made within 1 hr of the first. If more than one hour has <br /> expired between the first and second application,the use of LEVELROCK brand primer is recommended <br /> between applications to insure proper bonding. The thickness of the second application should be such that <br /> the gypsum cementitious underlayment shall be a minimum of'h"over the top of the radiant heat tubes. <br /> Concrete must be properly cured a minium of 28 days prior to the underlayment installation.Immediately <br /> spread and screed product to a smooth surface.Except at building joints,place product as continually as <br /> possible so that no slurry is placed against product that has obtained an initial set. Care must be taken to <br /> protect radiant heating tubing during the application of the gypsum underlayment <br /> Place lightweight g,ypsum concrete in accordance with manufactures instructions,using <br /> equipment and procedures to avoid segregation of mix and loss of air content. Deposit and screed in a <br /> continuous opera.tion until a continuous section is completed. Do not vibrate or work mix except for <br /> screeding or floating. Place material to depths shown.L:eave top surface in smooth condition to receive <br /> finish ed flooring application. Bedrooms shall a rough finish to receive the%2' layer of waterproof concrete. <br /> B. Begin curing operations immediately after placement,and air cure for not less than 3 days in <br /> accordance with manufacturer's recommendatioas. <br /> Page 2 of 3 <br />