QUESTION

Ceramic Tile Hollow and Grout Cracking - Could you respond to the following case scenario?

PROBLEM:
We installed two ceramic tile floors. They have both developed the following problems:

1. THE GROUT IS CRACKING
2. THE TILES ARE NOT ADHERING TO THE MORTAR BED (POOR OR NO ADHERENCE TO MORTAR)

EXTENUATING CIRCUMSTANCES OF THE INSTALLATION :

1.WE HAVE LIMITED CERAMIC TILE INSTALLATION EXPERIENCE. (WE’RE NOT PROFESSIONALS)

2.WE DROPPED THE TILES INTO A BED OF MORTAR ON CONCRETE BACKBOARD.

3.WE LATER READ ON THE BAG THAT WE WERE SUPPOSED TO PUT A SKIM COAT OF MORTAR ON THE BACK OF THE TILES BEFORE DROPPING THEM IN THE BED OF MORTAR. . (WE DIDN’T DO THIS)

4.THE INSTALLATION TOOK PLACE DURING A VERY COLD STRETCH OF WEATHER. THE MORTAR AND GROUT WERE MIXED IN A 15-20 DEGREE GARAGE. WOULD IT MATTER IF THEY WERE IN THAT COLD BEFORE OR AFTER MIXING?

5.THE TILES THEMSELVES WERE STORED IN THE SAME 15-20 DEGREE GARAGE. THEY MAY OR MAY NOT HAVE BEEN ROOM TEMPERATURE WHEN INSTALLED.

6.THE ROOMS WHERE THE INSTALLATIONS TOOK PLACE WERE BOTH INTERIOR ROOMS.

Finally, how would we go about repairing the floors? Should we pop up and repair as many as possible or is something else required? We're not looking for any short cuts. We want the floors to be the best they can be. CAN YOU HELP?

ANSWER

ANSWER - Regarding your description of your tile problem I will give you some input. We do inspections around the country, so we can be hired to investigate your problem (click here for forensic failure investigations).

1. Cracking grout is an indication of excessive movement.

2. If the tiles were not well attached to the substrate then that is the likely cause.

3. You said that the tiles did not adhere to the mortar bed, which I assume was a cementitious backer board unit (CBU) per your description. So I then assume that the thin-set mortar adhesive did adhere to the back of the tile.

4. If the thin-set came up clean from the CBU that is an indication that there was a contaminate bond-breaker present. That could be dust, a sealer, or anything that would interfere with the bonding.

5. If the CBU was over a wood sub-floor and it had excessive deflection more than L/360 that could also contribute to the cracking grout. If the thin-set was poorly attached then the deflection might have caused the thin-set to lose bond.

6. Yes, you should skim coat or key in the thin-set into the substrate and the back of the tile to ensure a good bond.

8. The cold weather could retard the curing of the thin-set that then if it was walked on too soon it could cause loss of bond. The temperatures are below what the manufacturers of the installation products recommend, so there could be a problem with the thin-set not being mixed properly.

7. The only way to determine the problem, and there are likely compounding problems, would require doing an intrusive investigation. It normally costs anywhere from $1,500 to $2,500 or more depending on how many issues and how much time it takes.

8.  Unless we know the true cause of the problem we can't prescribe a remedy.  Grout joints should not crack and tiles should be well attached, so at least those need replacing, but depending on the actual problem, the tiles you don't replace may eventually have the same problem.