FLEX R20 UNMODIFIED MORTAR, APPROVED BY SCHLUTER® SYSTEMS®
As the name suggests, an unmodified mortar is a mortar that contains no polymers, which limits its use - it can only be installed on concrete, indoors. However, SCHLUTER® Systems® recommend its use with DITRA® and KERDI® membranes. But why an unmodified mortar? According to data provided by SCHLUTER ® Systems®, modified thin-set mortars are not recommended to set tile over DITRA® or KERDI® because these mortars must air dry to cure properly. When sandwiched between two impervious layers such as DITRA® or KERDI® and porcelain tile, drying takes place very slowly through the open grout lines, and extended cure times would be required before grouting. If extended cure times were not observed, the results could be unpredictable. On the other hand, unmodified mortars have a chemical cure which is not affected by moisture level. An unmodified mortar is therefore the best choice for this type of application.
Mixture: SCHLUTER ® recommends preparing a mixture with higher water content for the installation of its membranes, and respecting the recommended ratios for installing tile.
SCHLUTER® Systems® have now acquired a worldwide reputation. PROFIX has developed a mortar based on their recommendations for the installation of KERDI® and DITRA® membranes. We have created a particularly creamy mortar that will help you in your work. We also have more control over the initial drying period, which is crucial during an installation, especially for a waterproofing system.