How do I prevent efflorescence in a tile installation?


How do I prevent efflorescence in a tile installation? - I am currently working on an outdoor deck (not over living space) for a residential, coastal, home. I am installing a 18"x 18", 1-1/2" thick, pre-cast concrete paver over typical reinforced mortar bed. My question: do you know of a "low salt" thin set / mortar bed product(s) that I could use to help decrease any efflourescence? Any other tips?


ANSWER - If you use a latex in a dry set thin-set mortar rather than adding water to a modified thin-set mortar you will reduce the mineral content in the thin-set, but probably not significantly.  You could use epoxy grout to minimize efflorescence through the grout, but with a concrete paver you could potentially get efflorescence and spalling on the porous tile.
The source of the minerals that drive efflorescence and spalling from the migration of moisture is normally primarily within the concrete or mortar bed substrate, and the best way to control efflorescence is by controlling the moisture.  The best solution is to put a tile ANSI A118.10/12 waterproof/crack isolation membrane over the mortar bed and bond the tile to it.  Make sure the slope of the primary waterproof membrane on the deck and the mortar bed are sloped to drain at least 1/4" per foot and that the moisture has a good path of escape at both membrane levels.

When there are serious efflorescence and spalling conditions it is because the substrate and tile are being subjected excessive moisture due to poor design or improper tile installation.  Good Luck.

Leave a Reply

Your email address will not be published. Required fields are marked *