commences. Before starting, substrates are to be cleaned to remove concrete curing compounds, sealers, soil, mortar, dirt, dust, paint, etc. Curing compounds and sealers must be removed by bead-blasting, grit / sand blasting, hydro blasting, diamond wheel grinder with dustless vacuum attachment, or equivalent methods of mechanical scarifying. For tiles with edges shorter than 15” (375mm), maximum allowable substrate variation is ¼” in 10’ (6mm in 3m) from the required plane, with no more than 1/16” variation in 12” (1.5mm variation in 300mm), when measured from the high points in the surface. For tiles with at least one edge 15” (375mm) in length, maximum allowable substrate variation is 1/8” in 10’ (3mm in 3m) from the required plane, with no more than 1/16” variation in 24” (1.5mm variation in 600mm), when measured from the high points in the surface. Use either LATICRETE ® 3701 Fortified Mortar Bed, or LATICRETE ® NXT Level Plus (interior only), and related LATICRETE ® NXT Primer, as a self leveling underlayment. Dry and dusty concrete and masonry surfaces are to be water washed, with excess water removed, just prior to the application of LATICRETE ® Systems Materials. EXPANSION AND CONTROL JOINTS Provide control or expansion joints as located in contract drawings and in full conformity, especially in width and depth, with architectural details. Substrate joints must carry through, full width, to surface of tiles. Install expansion joints in tile work over construction/cold joints or control joints in substrates. Install expansion joints where tiles abut restraining surfaces (such as perimeter walls, curbs, columns), changes in plane and corners. Joint width and spacing depends on application - follow TCNA “Handbook for Ceramic, Glass, and Stone Tile Installation” Detail "EJ-171 Expansion Joints" or consult sealant manufacturer for recommendation based on project parameters. Joint width: ≥ ⅛ ” (3mm) and ≤ 1” (25mm). Joint width: depth ~2:1 but joint depth must be ≥ ⅛ ” (3mm) and ≤ ½” (12mm). Layout (field defined by joints): 1:1 length: width is optimum but must be ≤ 2:1. Remove all contaminants and foreign material from joint spaces/surfaces, such as dirt, dust, oil, water, frost, setting/grouting materials, sealers and old sealant/backer. Use LATICRETE ® LATASIL ™ 9118 Primer for all porous tile installations to increase sealant adhesion. Install appropriate backing material (e.g. closed cell backer rod) based on expansion joint design and as specified in section 07 92 00. Apply masking tape to face of tile, brick or stone veneer. Use caulking gun, or other applicator, to completely fill joints with sealant. Within 5-10 minutes of filling joint, ‘tool’ sealant surface to a smooth finish. Remove masking tape immediately after tooling joint. Wipe excess sealant off all surfaces immediately. SELF-LEVELING UNDERLAYMENT INSTALLATION If replacing an existing floor, all original finish and installation materials must be removed down to fresh substrate BEFORE Surface Prep stage can begin. Use LATICRETE ® NXT Level Plus, and related LATICRETE ® NXT Primer, as a self leveling underlayment to attain proper floor flatness, on interior applications only. Surface Preparation - Concrete slabs must have a minimum ICRI concrete surface profile (CSP) of 3. For more detailed ICRI CSP information refer to ICRI Guideline No. 03732. Use of chemicals to remove contaminants or to create a surface profile is not recommended. Use of a sweeping compound is not recommended as they may contain oil which will act as a bond breaker. Additionally, concrete slabs must readily absorb water, be clean, free of oil, wax, grease, sealers, curing compounds, asphalt, paint, deicing agents, dust, dirt, loose surface material and any other contaminant that will act as a bond breaker. In addition, tensile strength testing of the concrete substrate, per ASTM C1583 or ICRI Guideline No. 03739, must show a minimum of 72 psi (0.5 MPa) tensile strength prior to installation of LATICRETE self-leveling underlayment. Any areas that do not meet 72 psi (0.5 MPa) tensile strength must be removed and repaired.
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