Floors, Interior - Ceramic or Porcelain Tile

24” (610 mm) o.c. joist spacing, double layer OSB or plywood subfloor

Areas of Application
  • over any even and structurally sound OSB or plywood subfloor with 24" (610 mm) o.c. joist spacing
  • interior dry or wet areas


  • minimum 2" x 2" (50 mm x 50 mm) tile



*** Essential
**   Significant
*     Helpful


  • maximum spacing of I-joists or floor trusses is 24" (610 mm) o.c.
  • double layer wood floor consisting of:
    - minimum subfloor thickness - 23/32", 3/4" nom. (19 mm) tongue-and-groove
    - minimum underlayment thickness - 11/32", 3/8" nom. (10 mm)

Substrate Preparation

  • verify that subfloor panels are properly fastened to framing members
  • underlayment – minimum 11/32", 3/8" nom. (10 mm)-thick eposure 1, plugged-face plywood or OSB with 1/8" (3 mm) gap between sheets 
  • any leveling of the assembly must be done prior to installing Schluter-DITRA and Schluter-DITRA-XL

Movement Joints

Setting and Grouting Materials

  • latex portland cement (p.c.) mortar - ANSI A118.11
  • 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

Other Considerations

  • tightly butted and/or tented plywood or OSB seams must be addressed prior to installing Schluter-DITRA and Schluter-DITRA-XL
  • vapor barrier on crawl space floors according to regional building codes
  • where a waterproof floor is required, all Schluter-DITRA and Schluter-DITRA-XL seams and floor/wall transitions must be sealed with Schluter-KERDI-BAND using unmodified thin-set mortar; see waterproofing requirements for more details