concrete slabs [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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12-18-2011, 03:10 PM
Have an existing 4 in slab that was an outside porch. Client wants to enclose porch for living space. Will need to bring up height 2 in to match other floor.( inside). Can I drill into existing slab putting rebar plugs. Make a surry coat of laytex and portland cement lay down metal lath and pull a mud bed of sand and cement to the height that is needed. Putting expansion joints in every 12 feet. total area is 450 sq ft. Tearing out old slab really is not an option. Will be installing 18 x18 tile with epoxy grout on final product

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12-18-2011, 03:56 PM
Welcome, Matt. :)

In that situation I'd recommend you not bond your deck mud to the slab but rather use a cleavage membrane and install a reinforced mud bed over that. Provides a bit of isolation from the slab and gives you a good surface for your tiling. The reinforcement needs to be welded wire mesh of a minimum 2x2" 16ga. wire mesh and must be in the vertical center of the mud.

Be good if we could see some photos of the condition of the existing slab.

Do you know if there is any vapor barrier under this slab? Think I'd wanna check the moisture vapor emission rate after the new room was closed in and climate controlled.

Curious about the reason for using an epoxy thinset mortar over such a mud floor.

My opinion; worth price charged.

12-18-2011, 05:32 PM
Yep, perfect place for a mud floor. *IF* the concrete is in good shape structurally. :)