Heated Floors, Interior - Ceramic/Porcelain Tile

• where radiant heat tubes are laid over the subfloor, gypsum or concrete fill poured to a height that is 3/4” (19 mm) above the tops of the tubes is required before installing Schluter-DITRA matting
• residual moisture in gypsum concrete, 2.0% (percentage by volume) or less before installing Schluter-DITRA

Substrate Preparation

• for wood substrates, subfloor/underlayment configuration according to detail16" (406 mm) o.c. joist spacing 19.2" (488 mm) o.c. joist spacing 24" (610 mm) o.c. joist spacing
• gypsum or concrete – follow manufacturer’s directions and/or design specifications
• additional substrate preparation according to heating system manufacturer’s directions

Movement Joints

• Schluter-DITRA does not eliminate the need for movement joints, including perimeter joints, within the tiled surface. Movement joints should be installed in accordance with industry standards and norms; see guidelines for the placement of movement joints for more details

Setting and Grouting Materials

• unmodified thin-set mortar – ANSI A118.1
• grout – ANSI A118.3, A118.6, A118.7, A118.8

Setting and Grouting Specifications

• tile - ANSI A108.5
• grout – ANSI A108.6, A108.9, A108.10
• heating system – follow manufacturer’s directions

Other Considerations

• if gypsum concrete is used, follow gypsum manufacturer’s recommendations regarding primers and/or special surface preparation before installing Schluter-DITRA
  
• vapor barrier on crawl space floors according to regional building codes
  
• where a waterproof floor is required, all Schluter-DITRA seams and floor/wall transitions must be sealed with Schluter-KERDI-BAND using unmodified thin-set mortar; see waterproofing requirements for more details
  
• certain moisture-sensitive stones, e.g., green marble, or resin-backed tiles may require special setting materials. Consult stone supplier and Schluter-Systems for more information