Flexy Mud Bed [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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02-18-2010, 01:35 PM
Have a project going in. Exterior residential entry decks. Bottom-up is:
wood framing,
self-adhered sheet waterproofing,

"cement lath" (expanded metal lath and waterproofing-resin-modified cementicious coating),

Enkasonic sound mat,

loose-laid diamond lath,

deck mud (1:4 field mix by machine mixer),


12x12 ceramic floor tile.

Before the sound mat was laid, the substrate was very stiff. But after the mat lath and deck mud went in, there were some flexy areas at edges (like at thresholds, drains, against walls, etc.) where foot pressure created a slight but noticeable deflection of the sound mat and mortar bed.

Of course the Enkasonic is cusiony, and the datasheet has a deflection chart listing various pressures (like .075"--about a 1/16-inch under 400-lb/SF). But they also show an approved detail with tile on a reinforced 1-1/4" mortar bed over the sound mat.

Should I be wary of setting the tile on this flexy bed, following the manufacture's detail?

Anyone experience this? Tile over a sound mat?

Brad in SoCal

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Rd Tile
02-18-2010, 04:45 PM
Should I be wary of setting the tile on this flexy bed

I would be.:)

02-18-2010, 05:16 PM
Any experience with mortar bed over sound mat, Richie?

Rd Tile
02-19-2010, 07:57 AM