Schluter-DITRA and Schluter-DITRA-XL
Specifically designed as an underlayment for ceramic and stone tile
Ceramic and stone tiles are durable, easy to maintain, and hygienic, representing the ideal surface coverings.
However, today’s lightweight construction methods can make the installation of hard surface coverings particularly challenging. In order to protect the integrity of the tile assembly, an underlayment that performs multiple functions is required.Schluter-DITRA and Schluter-DITRA-XL are specifically designed to allow the installation of ceramic and stone tile over any even and load-bearing substrate. The integration of four functions—uncoupling, waterproofing, load-distribution, and vapor management—makes consistent results viable through the use of Schluter-DITRA or DITRA-XL.
Every substrate presents unique challenges
Wood Substrate
All wood materials, including OSB, plywood, and framing members, are subject to expansion, contraction, bending, and deflection as a result of changes in moisture content and loading. Further, these deformations fluctuate over the life of the building structure.
Concrete Substrate
There are various challenges associated with the installation of hard surface coverings on concrete substrates. To begin, the coefficient of thermal expansion of concrete is close to twice that of ceramic tile. Additionally, tile contractors are often expected to install tile over young concrete (concrete cured less than 28 days). However, rigid surface coverings installed over young concrete are susceptible to damage as a result of shrinkage during curing.
Pre-stressed/ post-tensioned concrete slabs are also commonplace in today’s construction environment. Although pre-stressing is used to help control deflections in concrete structures, these slabs are still subject to deformations caused by changes in moisture, temperature, and loading. Many concrete slabs on or below grade are subject to moisture migration, which can be problematic. Furthermore, these structures experience the same deformations as stated above.
Gypsum Substrate
Bonding ceramic or stone tiles directly to gypsum concrete substrates is generally considered questionable or not recommended. The challenges associated with gypsum-based underlayments include the requirement of an extended drying period before installing tile and continued sensitivity to the reintroduction of moisture throughout the life of the installation.
In addition, since the coefficient of thermal expansion of gypsum concrete is substantially greater than that of ceramic tile, shear stresses caused by temperature fluctuations can result in delamination or cracking of the tile covering. This is particularly important when gypsum concrete is used as a thermal mass for radiant heated floors. With the increasing popularity of radiant heated floors, which typically utilize gypsum concrete, tile installers need a reliable installation system to address these issues.
Heated Floors
Radiant heating is one of the fastest growing market segments in the construction industry. Unlike other surface coverings, the low thermal resistivity of ceramic and stone tiles allows them to be used in radiant heat applications without sacrificing the energy efficiency of the system. However, there are inherent challenges in combining rigid surface coverings with radiant panel heating systems.
A viable installation system must address the magnified fluctuations in temperature that contribute to increased shear stresses between the heated assembly and the tile covering. The system must also limit thermal striping by promoting even heat distribution and protect the assembly from moisture, which is particularly important when gypsum concrete is used as the thermal mass.
Exterior Application
Ceramic and stone tiles are ideal surface coverings for the exterior and have been used successfully for thousands of years. Exterior balconies and terraces are ideal opportunities for the installation of tiled surfaces. However, these installations have typically presented significant challenges to tile setters. Since hard surface coverings are rigid by nature and have different physical properties compared to virtually every substrate, they cannot be bonded directly to the substrate, particularly in exterior applications where they are exposed to potentially severe climatic changes and the recurring introduction of moisture.
Uncoupling
Schluter-DITRA/ Schluter-DITRA-XL’s uncoupling function protects the ceramic or stone tile covering by neutralizing the differential movement stresses between the substrate and the tile, thus eliminating the major cause of cracking and delaminating of the tiled surface. This is particularly important since these stresses are magnified by the significant temperature gradients common to exterior applications.
Waterproofing
Schluter-DITRA and Schluter-DITRA-XL provide effective waterproofing that will protect the tile assembly from the recurring introduction of water, which is common in exterior applications.
Vapor Management
The free space beneath the Schluter-DITRA/ Schluter-DITRA-XL matting provides a route for any residual moisture in the substrate to escape. This is especially important when installing tile over a young slab, concrete slabs subject to moisture migration, or a fresh mortar bed.
Support/ Load Distribution
Since Schluter-DITRA and Schluter-DITRA-XL are virtually incompressible within the tile assembly, the advantages of uncoupling are achieved without sacrificing point load distribution capabilities.