Thread: Ditra install
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Unread 06-11-2019, 11:19 AM   #11
Veteran DIYer- Schluterville Graduate

STAR Senior Contributor

Join Date: Jul 2004
Location: Nashua, NH
Posts: 14,230
IF you're using chalk lines on Ditra, the magic solution is hair spray. After snapping the line, give it a spritz of hair spray. It will stay in place then. As said, the thinset doesn't stick to it, so it doesn't produce a bond breaker situation. The dovetail holes in the mat are what holds the thinset and therefore the tile in's not a cement bond to the mat (but is to the tile).

The holes in Ditra will be solid if you prefill, but any thinset that is above them tends to crack and flake off if you walk on it, and that should be removed prior to later applying the setting bed and tile. So, in some ways, it's more work, but you will save some money rather than throwing away excess, it's a tradeoff of time versus money. Unless you contaminate the prefill, new thinset will bond to the old. You will find it works best, similar to most things, to wipe the surface with a damp sponge prior to spreading the thinset, as what's already there will tend to suck moisture out of the fresh stuff unless you add some first, making it get stiff sooner.
Jim DeBruycker
Not a pro, multiple Schluter Workshops (Schluterville and 2013 and 2014 at Schluter Headquarters), Mapei Training 2014, Laticrete Workshop 2014, Custom Building Products Workshop 2015, and Longtime Forum Participant.
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