Spot-bonding to cure an uneven substrate is a no-no that even a customer can recognize
Unacceptable methods and unskilled installation set the stage for future problems
By Lesley Goddin
Sometimes the correct and incorrect ways to install tile are so clear and intuitive that even a non-tile- professional, new homeowner, realizes something is amiss, even if “reputable” builders or less-informed tile installers do not.
Such is the case of a soon-to-be- homeowner, Sean Hobbs of Oviedo, Fla., and his wife Kimberly, who elected to inform themselves about materials and installation techniques as their home was being built. Some techniques seemed questionable, and Hobbs contacted NTCA for guidance in the matter.
Hobbs wrote, “The tile on the vertical walls of the showers are being applied using a ‘patty’ technique. We wouldn’t have been aware of this except that the water proofi ng Hydro Guard 1 was left unfi nished on one of the showers and the tilers needed to remove the tile to correct this. Not a single one broke. Mike Holmes of Holmes on Holmes and Holmes Makes it Right on HGTV described tile coming off easily and without breaking as a sign of poor work, so from this I felt the work wasn’t being
“It seems that the voids left by the patty technique would be undesirable and potentially weak areas should they get knocked,” Hobbs astutely observed. “I thought the only technique was to apply the thinset to the walls, use the notched trowel to comb the thinset, place the tiles, and try to get as close to total surface contact with the back of the tile. Some even recommend taking off every fifth tile to confirm this by inspecting the back. Others recommend a very thin ‘back buttering’ of the tiles to be sure of this total contact.”
Hobbs is speaking the language of the skilled tile installer here! He scoured the internet for proper tech- niques, which he shared – to no avail – with his builder. He revealed, “My wife and I were told by the builder that the directions on the bag of thinset were merely ‘recommendations.’”
The builder insisted that he is following best practices and lets “’building science’ guide his build- ing materials and their installation,” Hobbs said. “As it stands now, he is accepting the tiler’s reasoning that the DUROCK® and PermaBase® walls – which the same tilers themselves installed just a few weeks ago – are a bit off and they need to use this patty technique to perfect the tile so that the look is right.” The builder main- tained that using the aforementioned proper method would not allow the installers to fine-tune their placement to achieve a good look due to the “suction” of the tiles.
Shoddy work on display
Hobbs observed that “such a small amount of thin-set patties were utilized, that tape and even screws (piercing the waterproof membrane) were used to hold the tiles up and prevent them from sliding. It is my opinion that one of the reasons the builder allowed this inferior work to be performed was to get the home ‘Parade Home-ready’ since our home – with the builder’s sign prominently displayed – was to be featured for a local annual public display of new and renovated homes.”
Hobbs sought recommendations from TCNA and received information from industry consultant Dave Gobis which included ANSI tile setting standards, and two articles – one of which, “Dots, Spots, Dollops and Whatever,” appeared in the April 2013 TileLetter.
“While the patty work continued, the builder was searching around to find some other ‘expert’ to refute Mr. Gobis’ perspective because the builder was sure it was simply a different technique,” Hobbs added. “Most of the remediation (certainly not my first choice) was to grout all but the top tiles, remove the top tiles, pour a slurry to fill the voids while gently tapping with a rubber mallet to help the slurry settle, and call it done.
“The builder states that he has filed paperwork with his insurance company just in case there are any future problems with this tile install for our home,” Hobbs said.
In addition to the wall tile fiasco, Hobbs specified and paid extra for Ditra uncoupling membrane he’d seen recommended by Mike Holmes. Floors in his former home had cracking tiles and he wanted to eliminate this in the new place.
“What we found by dragging a long thin metal rod lightly across our floors is that there are numerous and large areas of tile floor with 12”x12”, 12”x24” and 24”x24” in a Versailles pattern that are hollow underneath,” Hobbs said. “Our builder’s response when shown and allowed to hear this was ‘it’s hard to lay tile and get it just right.’ We have ongoing issues after moving in June of 2013.”
Bringing his concerns to the NTCA, he asked, “Am I being overly concerned here? Are these appropriate issues to bring up? Should I consult a local tile professional, possibly one in good standing with the National Tile Contractors Association organization, to get a second opinion?”
Well, dear reader, I can imagine that you are thinking, “You SHOULD be concerned, Sean!” and “Good eye!” Here’s how Gerald Sloan, NTCA presenter and technical con- sultant, responded:
“I highly recommend choosing a tile contractor that is a member of the National Tile Contractors Association,” Sloan said. “Please visit our website www.tile-assn.com, then go to member locator to find a member contractor close to you.
“As a member, the tile contractor is privy to yearly updates on industry- recognized installation standards and cautions, in addition to product limitations,” Sloan said. “Another great member benefi t is technical sup- port that comes from our Technical
Committee where issues that concern tile contractors are discussed with efforts to avoid actions that have caused tile installation-related failures. A member who is active in our association is well-armed to avoid potential failures due to inappropriate installation practices. We wish all tile contractors would be a part of the NTCA, so we could eliminate all installation related failures.”
Sloan addressed the folly of incorrect spot bonding especially to correct uneven substrate conditions.
“As for your question related to spot bonding the tile to correct out- of-plane or out-of-plumb wall substrate conditions, this is high risk for a failure due to several factors,” Sloan said. “One is, as you men- tioned, impact loads. Those areas behind the tile that do not have coverage are much more likely to break if an impact condition should occur.
“Another potential problem is in a wet environment such as a shower; open pockets can harbor dampness much longer, and the body oils and dirt from your body can penetrate through the tile and grout joint – even if it has a quality sealer on it,” Sloan said. “Over time, this mate- rial may accumulate and become food for B.O.G (biological organic growth) or mold.
“The other reason we should not spot bond with common multipurpose thin-set setting materials is because they have a high rate of failure due to product shrinkage,” Sloan added. “The multipurpose thin-set products we work with most often are not designed to be built up to more than 1/4” thickness as measured after the tile has been installed – remember it’s called thinset. If it exceeds maximum allowable finished thickness, it has been proven to fail due to shrinking as it cures.”
The Tile Council of North America Handbook for Ceramic, Glass and Stone Tile Installation has a generic caution given in the note section (p. 17 in the 2013 edition) about not using medium bed mortars to true-up underlying substrates, Sloan said. Additional recommendations for mortar use are listed on page 35 of the Handbook.
The ANSI Standards, on page 88, in section 22.214.171.124 in the Definitions of Latex-Portland Cement Mortar, state: “Modified dry-set mortars are designed as direct bond adhesives and are not intended to be used in truing or leveling underlying substrates or the work of others.”
Bart Bettiga, NTCA executive director, jumped in on the discussion. “We don’t specifically have a section that addresses spot-bonding or pattycaking because, until recently, we were not aware that this practice was gaining steam,” he said. “We intend to alert our ANSI and Handbook committees that we may need to go even further to address this.
“There is a reason why patching and leveling products are made; because they are designed for these purposes,” Bettiga added. “The mortars that are manufactured to be used to direct-bond tile and stone are formulated to be spread to a certain thickness. When you deviate from this intention, you defeat the intended purpose of the products. We are not aware of any thin-set manufacturer that would recommend or warranty their products to be used in this fashion.”
Instead of using mortar to even up the substrate, Sloan said, “If the framing is out of plumb, framing should be corrected by shimming, sistering, scabbing, or total removal and replacement. Do not true up with thinset because the thicker places shrink more than the thinner places, thereby creating stresses that often cause the loss of bond to the tiles in random areas. The American National Standard Institute has a thin-set coverage requirement under A-108 which mandates wet area tile installation thin-set setting coverage to be 95% – 80% coverage for dry areas – with all edges and corners covered.”
This game of “patty-cake” played by the builder is setting the ground- work for future problems, ones that he has opted to cover by insuring the work instead of doing it right from the beginning.