Asked by: Llara Dañobeitia
asked in category: General Last Updated: 4th February, 2020

Can you use modified thinset over Kerdi?

Modified thinset mortars aren't recommended for use with Kerdi because they must dry out to gain strength, whereas the membrane inhibits drying, which can lead to unpredictable results. For example, if a shower is used before the mortar has cured properly, leaks and polymer leaching can occur.

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Keeping this in consideration, should I use modified or unmodified thinset?

It's important to note that latex-modified thinset can still be used between the membrane and the subfloor because it is not impervious. However, unmodified thinset should be used between the membrane and the tile.

Subsequently, question is, can you mix modified and unmodified thinset? When it comes to thinset, choosing between modified or unmodified thinset can leave many tile installers scratching their heads. More than that, you don't have to mix some types of modified thinset with water before spreading it out on the subfloor.

Thereof, what Thinset do I use with Kerdi?

Unmodified thin-set mortar is recommended to set ceramic and stone tile, including large format tiles, over the KERDI membrane. Portland cement-based unmodified thin-set mortars are dependent on the presence of moisture for hydration in order to gain strength.

Is unmodified thinset waterproof?

All portland based cementious products will allow water to pass through. The latex modified is more resistant due to the latex that is mixed in with the adhesive but that doesn;t make it "waterproof". The latex also allows a bit more flex in the tile and substrate. As Jason described, thinset itself isn't waterproof.

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