Ceramic Tile Underlayment on Slab

[imported_John Smith]

An aquaintance of mine indicated his 4 year old home was starting to have some of the ceramic floor tiles loosen up. The house has a post tensioned concrete slab. He indicated that there was some "black stuff" between the ceramic tile, thinset and slab. The way he described it, it sounded like tar paper.

I haven't personally seen it yet, but I haven't seen anything go between the slab and tile (other than thinset) on any houses I have looked at during new construction.

For what its worth, he indicated the house was built by Village Builders.

Is this something used as a vapor barrier?

I will try to get some photos of it.

[Michael Thomas]

CIM? (Crack Isolation Membrane):

FIELD REPORT 109 (http://www.ctioa.org/reports/fr109.html)

[James Duffin]

I've seen drainage mats under some tile jobs but that is normally found under a high end tile job.

[Dom D'Agostino]

Tar paper makes a poor crack isolation membrane, but some tile installers still use it.

[Jerry Peck]

Tar paper makes a poor crack isolation membrane, but some tile installers still use it.


Felt paper is a *worse than poor* crack isolation membrane and *SHOULD NOT BE USED for that purpose.

A crack isolation membrane should not be affected by water or moisture, and felt paper is. It will, *of course*, wrinkle when it gets wet, which will, *of course*, de-bond itself from the thin set.

The Tile Council of America and the Marble Institute of America have specific guidelines and requirements for the use of crack separation membranes, and one is (if I remember correctly) the forbidden use of thin set when a crack isolation membrane is used. When a crack isolation membrane is used, a mud set is required to be used on top of the crack isolation membrane - otherwise the tile will crack, come loose, or 'tent'.

[Scott Patterson]

For what its worth, he indicated the house was built by Village Builders.


Most homes are built by folks who come from the Village! :D

[imported_John Smith]

Scott,
I thought they were built by the Village People.
Seriously thanks for all of the replies guys.
I will try to get some photos and determine whats really going on.
A 4 year old house with these types of problems (oh yeah he has a water leak in a wall somewhere) is unfortunate for the homeowners, but makes it a lot easier to sell the public on the true value of home inspection!