Crack in Slab [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Tile Rookie
06-18-2001, 03:31 PM
He's back! Need more info on cracks in concrete slabs. While scraping adhesive off the slab I noticed a small crack. It's less than a sixteenth of an inch wide and runs perpendicular to the hallway, about 3 feet long. One end is a little wider, but still less than a sixteenth of an inch. It's stops on one end, but the other end dies into a tile job from previous owners. That tile does not show any cracks. The house was built in 1979. I have looked through previous entries and still need to know more about fixing the crack before I start to tile. I'm putting down 15 x 15 inch porcelain tiles. This is the only crack in the slab. You guys have written about using isolation membranes - I think they are called - but I have never used one of these. Any ideas on where to start? Thanks for all your help

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06-18-2001, 04:15 PM
Schluter is one of,if not THE,top manufacturers of this type of underlayment.Their product is called DITRA.It comes in rolls and is very easy to work with.It is set on a bed of thinset then tile is installed on top of that.

It is also known as an "uncoupling" underlayment.This means that it isolates the tile from slab movement and stops cracks from transferring to the tile.

There are other companies that make similar products.Some of these other guys can give more info on those.

Installing 15" tile you may find it necessary to use an SLC(Self Leveling Cement) to flatten the floor.Or possibly use a medium bed mortar to avoid "voids" under the tile.

John Bridge
06-18-2001, 05:10 PM
I use a product that is thinner than Ditra. I use it just in the area of the crack, not over the entire floor. You can order a kit for about $90 that'll take care of just about any situation, save an utter disaster.

Semco is another product I'm familiar with. It is a trowel-on membrane.

A bucket of Semco costs about the same as the Protecto Wrap kit. There are, of course oodles of other products out there. Some of them are hard to acquire in small quantities, though.

Derek & Jacqui
06-18-2001, 05:21 PM
Flex Guard
Crack Isolation Protection for Ceramic Tile.
1-800 279 7600.
Haven't used this one, but something similar and it works.

06-18-2001, 07:27 PM
Welcome back!!

How about if you contact some of the local tile distributors to include the Big Orange Box, and let us know what they are recomending?

We will help you from there and it will give us a little perspective on how things are done in your market. It may also help us make a determination on who to recomend your friends and neighbors to in the future.

As John said, there are a multitude of products out there that are suitable for this application.

Art Phenis

Bud Cline
06-18-2001, 07:36 PM
"Blue 92" by Laticrete.
Crack isolation product using fabric and paintable/ trowelable liquid. Paint an area three times the tile size in all directions from the crack, apply fabric over the crack and paint the area again. Drys fast, bonds to thinset.

Rob Z
06-18-2001, 07:50 PM
Hi T.R.

The fact that you are trying to deal with the crack makes you more professional than some of the "pros"!
You wouldn't believe some of the stuff I've seen the "pros" set tile over. (How about drywall compound as a feather patch?)

Let us know which products are available to you, especially those in small, affordable quantities. Between this band of merry men, we probably have used many of the products you'll encounter.


06-18-2001, 08:32 PM
How much is Blue 92 selling for in the corn husker state.

Just getting some info for comparitive prices to the competition.

Of course the thin set you reffered to in your post is in fact, multi purpose?


Bud Cline
06-19-2001, 09:21 AM

Most of these products are acquired by me through the retailers I work for, I haven't bought any of this stuff direct in a long time. The retailers like to keep their costs a secret as well as their markup to the customer. In fact everything is a big secret around here with these guys. Most of my work is "high-end" thru these guys and they charge (for example) $25 for a 3 x 5 sheet of 1/2" CBU (they buy by the pallet) that I can buy for $9 at the local big box. They get away with it routinely.

More power to them, I guess. This is how they can afford to use some of the hacks they use and some of the jobs they eat.