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Unread 11-01-2018, 10:37 AM   #131
ss3964spd
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Location: Fairfax, Va
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Shower floor and main floor build ups

Am not far from starting to prep for floor tile for my curbless shower and main bath floor. That prep includes setting the foam shower pan and the Ditra heat mat (only on main floor). The tile on both floors is 3/8"

I'd really appreciate a sanity check.

Shower Floor Build up from subfloor, cutting trowel thickness in half for actual mortar thickness:
Hardie wants 1/4X1/4 Sq notch trowel
USG wants 1/4X3/8 sq or U notched trowel for the pan to Hardie
USG wants 1/8X1/8 sq or U for the membrane to pan

It builds up like this:
1/8" mortar
1/4" Hardieboard
1/8" mortar
1" USG foam pan
1/16" mortar
USG membrane

Sooo, the shower floor comes out to about 1 9/16" thick, not including the membrane thickness.

Main Floor Build up from subfloor, cutting trowel thickness in half for actual mortar thickness:

It builds up like this:
3/4" plywood
1/8" mortar
1/4" Hardie Board
1/8" mortar
1/4" Ditra Heat Mat

So the main floor comes out to 1 1/2" thick, a difference of 1/16th between the two.

Where/how can I make up the difference? The shower floor tiles are 2X2's on a mesh backing. I've read that a smaller trowel notch size should be used for them to avoid mortar squeeze out (I'll probably use a 1/2X1/2 trowel for the 12X24 main floor tiles). Will using a smaller notch size for the shower floor tiles do the trick? If so, what size, 1/4X1/4?

Many thanks,
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