lath or not? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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09-07-2010, 05:42 PM

New shower. 1/2 inch hardi backer board up on the walls. custom shower pan using pvc liner and deck mud.

1. since I'm using hardi board do I need to lath and float the walls ...can I go directly to thin set and tile? (Kerdi used on joints and corners)

2. do I set the first course of tile directly on the floor or up 1/2 inch?

3. If I don't set the tile directly on the floor do I slide the floor tile under the edge of the wall tile?

4. going to use nu-heat on floor.should I preset in thin set or can I put down thin set on wires and tile directly? all in one shot?

Many Thanks


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09-07-2010, 05:53 PM
Welcome, Paul. :)

1. You can float the walls if you want, but there is no need to do that over a fiber/cement board.

Kerdi on joints and corners might work OK to satisfy the Hardi requirement for taping and filling the joints, but is also unnecessary. You can do the same with alkali-resistant mesh tape and thinset mortar.

If you're doing the Kerdi Band as a waterproofing step, that won't work either unless you cover the entire wall structure.

If you didn't install a moisture barrier behind the Hardibacker, you'll need some sort of waterproofing membrane over the inside surface, anyway.

2. You can do the wall/floor sequence in any order you like. Some do the floor first, some do the walls first, some do the walls starting with the second row and then do the floor and bottom row, some don't ever tile a shower at all. :)

3. You can do that.

4. You might wanna check with Nu Heat about using their product in a wet area. In any case, you wanna follow their installation recommendations, which will call for filling over the wires prior to tiling, I do believe.

Wouldn't hurt to tell us how you did the shower pan before you get too far to be able to correct anything you might have overlooked, eh? :)

My opinion; worth price charged.

09-07-2010, 07:12 PM

The pan was verbatim from this site's howto. Didn't alter anything. feel pretty confident about the pan. Saw one thread where they waterproofed the cement board. wasn't sure if that was over kill or required. Any recommendations on what to use for the waterproofing?


09-07-2010, 08:03 PM
If you didnt install a vapor barrier behind your ceement board you will need a surface applied waterproofing, which in many peoples opinion is much better anyway because the ceement board never gets wet.

hydroban, redguard, there are many to choose from just follow the individual manufacturers instructions cause some may call for the use of a fabric and all should be installed according to maufaturers specs.