Schluter®-DITRA is a polyethylene membrane with a grid structure of square cavities, each cut back in a dovetail configuration, and an anchoring fleece laminated to the underside. The anchoring fleece is embedded in thin-set mortar to provide a mechanical bond to the substrate. Tile is installed over DITRA using the thin-bed method in such a way that the mortar becomes mechanically anchored in the square, cutback cavities of the matting. Designed specifically for ceramic tile and dimension stone installations, DITRA serves as an uncoupling layer, waterproofing membrane, and vapor management layer that accommodates moisture from beneath the tile covering. Further, DITRA performs all these functions while still providing adequate support/load distribution for the tile covering. The combination of these four essential functions allows for the successful installation of tile over a wide range of substrates, including plywood/ OSB, concrete, gypsum, heated floors, etc. DITRA is 1/8" (3 mm) thick, which minimizes tile assembly thickness and reduces transitions to lower surface coverings (e.g., carpet, engineered wood, and vinyl). DITRA allows for ceramic tile application over single-layer plywood or OSB subfloors on joists spaced up to 19.2" (488 mm) o.c.
Tile has been successfully installed for thousands of years by incorporating an uncoupling layer, or forgiving shear interface, within the tile assembly. DITRA provides uncoupling through its open rib structure, which allows for in-plane movement that effectively neutralizes the differential movement stresses between the substrate and the tile, thus eliminating the major cause of cracking and delaminating of the tiled surface.
DITRA provides reliable waterproofing in interior and exterior applications. Its polyethylene composition protects the substrate from moisture penetration, which is particularly important in today’s building environment where most substrates are moisture-sensitive. Vapor management The distinguishing feature of DITRA is the existence of free space created by the configured channels on the underside of the matting. The free space provides a route for excess moisture and vapor to escape from the substrate that could otherwise cause damage to the tile layer above. Thus, DITRA effectively manages moisture beneath the tile covering.
When placed on a solid foundation, columns or pillars can support tremendous loads. The same physical principle applies to DITRA installations. Column-like mortar structures are formed in the cutback cavities of the matting. Loads are transferred from the tile covering through these column-like mortar structures to the substrate. Since the matting is virtually incompressible within the tile assembly, the advantages of uncoupling are achieved without sacrificing point load distribution capabilities. The ability of DITRA installations to support and distribute heavy loads while preserving the integrity of the tiled surface has been verified through extensive laboratory and field testing, including applications exposed to vehicular traffic.