November 21/28, 2016: Volume 31, Number 12
By Donato Pampo
Editor’s note: The following Q&As were reprinted with permission from the Ceramic Tile and Stone Consultants, CTaSC, which provides expert witness and forensic failure investigation services. In addition, CTaSC provides quality control services for products and installation methods, testing services, online and classroom training, market research and outsourcing services.
Excessive lippage on wood plank tiles
I recently had porcelain tile installed on a concrete slab by my GC. I am concerned with how the job came out. The installer did not do anything to level the floor. He told me he would use more or less thin set to make sure all the tiles were level, but I feel there is a lot of lippage.
Your floor tile appears to be a porcelain wood plank floor tile. With the ink-jet technology being used today in the production of ceramic tiles they can produce very realistic wood floor looks and natural stone looks. Installing the long, narrow-width tile planks is a difficult installation because these tiles do tend to have warpage and the shapes of the tiles being offset from each other with narrow grout joints is challenging. You have to properly prepare the substrate and be a good and patient tile installer to avoid excessive lippage.
There are industry standards on what is acceptable warpage in a porcelain tile as stated in ANSI A137.1. Approximately they are allowed to have up to about 1/16 warpage. How that warpage is distributed on the tile can be problematic if it is concentrated at any one portion of the tile. Acceptable lippage per ANSI A108.02 says that the tile lippage can’t be more than the inherent lippage of the tile being installed, assuming it isn’t more than the allowable lippage in ANSI A137.1, plus 1/32 for grout joints less than 1/4 wide, or plus 1/16 for grout joints 1/4 wide or wider. So potentially you could have 3/32 lippage or up to an 1/8 lippage, respectively, if the tile has the maximum allowable warpage.
From a standard of care point of view for professional tile installers, assuming this particular type of tile meets the standards, I would expect the lippage should not exceed 1/16. There are always exceptions depending on the type of tile being used.
Although, if the tile installer did not properly prepare the substrate so it did not vary out of plane more than 1/8 in 10 feet or 1/16 in 24, or if he did not properly adjust the tiles during the installation—or if the grout joint is too narrow—then you can get excessive lippage beyond what is acceptable.
Mold damage on Saltillo tiles
We have had two slab leaks and continue to be told there is no damage to the floor. Can concrete slab leaks cause mold damage on Saltillo tiles?
Assuming the Saltillo tiles are properly installed over the concrete slab that had the two leaks, and it was clean category 1 water and not unsanitary water, the tiles should not be harmed.
Mold is a microbial growth that is ubiquitous, and as long as there isn’t a food source or an environment that promotes mold growth then it will not perpetuate. Concrete has a high pH which does not allow mold to grow unless there is some other superficial organic food source. Sometimes if the tile is not installed correctly with the correct type of installation products, a water leak could result in some damages.
Cleaning a sealed tile floor
I have a ceramic tile that someone sealed with dirt on the tile. It may have been done over five years ago. I used a generic stripper, but it only improved the floor by 10%. What should I do to get this tile clean?
If the tile floor was sealed when it was dirty, then the only way to clean it is to remove the sealer.
To determine which stripper to use to remove a sealer you need to know what sealer was used.
If you don’t know which sealer was used then you have to experiment with different strippers. Aqua Mix and Miracle Sealants have strippers as well as other manufacturers of cleaners and strippers.
There are generic strippers like Goof-Off and some paint strippers that will remove some sealers. If it were practical you could have a testing laboratory test the coating that was scrapped from the tile to determine what it is and what solvent will remove it.
Porcelain tile debonding issues
We’re having a problem with porcelain tile debonding. (We have polished porcelain tile, 300 x 600 mm and 600 x 600 mm bent, four corner sides concave.) We have done testing on water absorption, moisture expansion and thermal shock—all passed ISO 10545 standard. What’s causing the shrinkage?
Considering it is a porcelain tile, I would think that the warped corners were that way when they were installed. Porcelain tiles are not moisture sensitive and they would not be expected to warp after they are installed. Having all four corners of the tile concave would be considered excessive warpage by U.S. standards.
A 2-3 mm grout joint is normally reasonable for a rectified porcelain tile installed in a soldier course pattern. (Tiles are not off-set from each other.)
The debonding of the tile should not be due to the tile unless the tile had some sort of contaminant on its back side that prevented the tile from achieving an adequate attachment to its substrate. Generally speaking, the reason tiles debond is because they are not bonded as well as they should be to their substrates and due to the tiles being subjected to some stress that is greater than they can resist. If the tile had a contaminant on its back side that acts as a bond breaker, or if the substrate to which it is attached has a contaminate that acts as a bond breaker, or if the adhesive is not suitable for bonding the tile can all be a possibility of why the tile was not better bonded to the substrate.
Tiles inherently are subjected to movement and resultant stresses caused by moisture or temperature or dynamic structural movement within the floor assembly. That is why it is required to have movement joints filled with a resilient sealant at all perimeters and transitions. Per Canadian standards, movement joints should be installed within the field of tile every 4800 mm to 6100 mm in each direction for interior applications; and every 2440 mm to 3600 mm for exterior applications and interior applications exposed to moisture and direct sunlight.
If there was new concrete installed that hadn’t cured for at least 28 days at reasonable temperatures, then it can have shrinkage that could subject the tile to more stress than it can resist. If the cementitious adhesive was excessively thick it can have excessive shrinkage that can contribute to the problem.
Fixing a terrazzo floor after a flood
My house flooded twice in less than 12 months. I have travertine tile on top of vapor barrier and below that terrazzo subfloor followed by another vapor barrier and then slab on grade throughout the foyer, family room and kitchen. Should the terrazzo be removed?
If the terrazzo floor was originally installed correctly, it should not have been harmed by the flood. If you had a vapor barrier on top of the terrazzo then it may not have been saturated with water during the flooding. But even if it had, it should be able to dry out and it should not be necessary to replace it.
When you replace the travertine floor, remove the vapor barrier under it and let the terrazzo floor dry for a few days with fans and dehumidifiers. You then can put down another vapor barrier over the terrazzo. Use a grade “D” breathable vapor barrier cleavage membrane if you are going to install a wire reinforced mortar bed over it. If you are going to bond directly to the terrazzo, I would first scarify it to open up the pores and then apply a liquid applied waterproof membrane that meets ANSI A118.10 and A118.12. This type of membrane is breathable and it is both a waterproof membrane and a crack isolation membrane. Make sure you run the membrane up the walls at least as high as the water gets. This way you can contain the water from future floods and limit the collateral damages.
If you are going to install a mortar bed over the terrazzo, then apply the waterproof membrane on top of the mortar bed and up the walls fto prevent future damage from flooding.
Donato Pampo, CTC, CMR, CSI, CDT MBA, is the founder and CTaSC and a leading tile and stone forensic expert and consultant in North America.