Don’t Get Floored By Mistakes

While that’s the obvious error of a novice, it’s not uncommon for these same experts to be called to assess jobs done by people with 10, 20, and even 30 years of experience that also failed – costing installers a bundle in the process.
Why can a good-looking floor go bad? Obvious suspects include poor surface preparation, use of the wrong grout or mortar, too much doctoring of commercial products or just plain bad technique.
Nothing is 100-percent foolproof, but following procedures and standards set by industry organizations, coupled with finding a family of products that you feel comfortable with, can go a long way toward eliminating those five-, six- and even seven-figure mistakes.

A LITTLE DAMP
At first glance, it’s easy to assume natural stone can handle just about anything. After all, it’s been sitting in the ground for billions of years. However, by the time it’s been removed from its natural setting, sawn into slabs and then further processed it’s not quite the same.
Add a little moisture to the mix, and you can end up with efflorescence or problems keeping a good bond from forming between the tile and the underlying concrete.
Don Halvorson of Thousand Oaks, Calif.-based Forensic Tile Consultants, says moisture content, rather than curing (or its lack) of concrete is the problem.
“One of the first things you should do when you go to a job is to check the moisture in the concrete,” he says. “You want to find out how much moisture is in the concrete and if it’s ready for tile.”
Lindell Lummer of Forensic Stone and Tile Consultants in Agoura Hills, Calif., agrees. He relates the story of a project he was called to after a granite-tile floor developed blistering.
“This was a large commercial project where they had compacted the soil, then put down 2” of sand and a 60-mil vapor barrier,” Lummer explains. “Then, they put another 2” of sand on top of it. They topped it with 5” of concrete, but the barrier turned up the sides of the stem wall, so they literally made a bathtub of concrete.”
He adds that while the concrete would probably have taken at least a year to cure on its own, it was tiled two months after the pour, thanks to a curing compound. However, the problem might have been avoided had the company installing the tile performed moisture testing.
Unfortunately, there’s no requirement to do moisture testing, although, “especially when they start using anti-fracture and waterproof membranes under the stone, they have to be set the same as resilient flooring, and in resilient flooring you’re required to do moisture testing,” Lummer says.
While this was a large commercial project, it’s a problem that isn’t exclusive to that venue. Halvorson says with developers putting up homes in as little as 60 days, it can certainly pop up in the residential market, as it did for him on a jobsite he was called out to where tiles developed a haze, even before the buyers moved in.
“It was efflorescing on a Crema Marfil tile,” he explains. “You could wipe it off, but it kept coming back because there was that much moisture coming in.”
His recommendation: Use one of the common methods for checking for moisture in the slab. And, if you don’t want to do either the calcium-chloride dome test or the concrete relative-humidity test, use a moisture meter – but understand the limitations and what the readings are telling you.
“In that problem with the efflorescing, the flooring contractor told me he’d checked the moisture in the slab and it was reporting two percent to three percent on 45- to 60-days-old concrete slab,” says Halvorson. “They were using a non-intrusive meter, but I don’t think they understood how to use it.”

BABY FACE?
Unfortunately, moisture isn’t the only problem that can keep a tile job from developing a good bond with its underlying concrete. There are any number of other things that can be contaminating that substrate surface.
Certainly one big concern is the use of curing compounds. Greg Mowat of Forensic Tile Consultants in San Diego (unafilliated with the Thousand Oaks firm) says not only is it used heavily (one estimate says on more than 95 percent of all jobs), but contractors often don’t pass along that information to subs.
“To start, I’d just pour a little water on the concrete to confirm it will absorb water,” he says. “If water won’t readily absorb into the slab, the mortar won’t bond to the slab or any adhesive.”
The problem is that the compound forms a film over the concrete, leaving a job that should either have a fine-broom finish, or be mechanically scarified. The same holds true for any concrete with a smooth steel-trowel finish.
“You want to know what the surface looks like – do a visual inspection,” says Halvorson. “If you don’t come in and grind and scarify the floor, you aren’t going to get a good bond. You really need to look at what you’re going to be working with.”
Scarifying has an additional benefit. It can clean up the debris left by the trades that have been there ahead of the tile setters.
“Quite often you’ll find the painters have gone in and sprayed the paint and varnish, and there’s overspray for 2’-3’ on the floor,” says Lummer. “We’ll go in, when there’s a problem, and find it’s well-bonded in the center for the room, but for those 2’-3’ around the perimeter, and in little rooms like bathrooms, there are problems.”
Admittedly, scarifying isn’t an inexpensive proposition. Lummer says he paid more than $10,000 for his machine and the necessary vacuums to eliminate the dust that goes with it, and hiring a contractor to do the work can cost more than $1 a square foot. However, having a job fail won’t be inexpensive, either.
“The MIA (Marble Institute of America) manual says you have to have a fine broom finish, no curing compounds or paint or residue, or the floor has to be mechanically scarified,” says Lummer. “If there’s a problem, and the tile contractor hasn’t scarified the slab, he’s in trouble.”

NOT-SO-SOLID
Just as moisture can seep through billion-year-old stone, it’s a material that’s not as stable as the uneducated might assume. Problems of expansion and contraction, and of deflection, can also contribute to tile floor failures.
Tile and stone are dynamic materials. Lummer says, for example, that 100 lineal feet of the quarry tile used in the kitchen area of a McDonald’s restaurant can grow to 100’ 1-1/2” in the sun. Wetted down in the sun, it will expand an additional half-inch.
“The biggest problem I see when I go out on inspections is that there are no expansion joints,” he says.
“The biggest thing I get calls on is tenting of tile on the floor because of lack of expansion joints and an understanding of perimeter isolation,” echoes Halvorson.
And, there really isn’t any excuse for it, says Mowat.
“Both the MIA and the Tile Council of North America (TCNA) spell out the requirements for expansion joints,” Mowat says. “Anything thinner than dimensional stone is installed as tile, and tile has to have expansion joints.”
“You don’t see many residential failures because they didn’t have expansion joints going through the floors,” says Lummer. “However, at the perimeters of the room you need at the very minimum a quarter-inch space where you keep the thinset and the grout out.”
He adds that architects and designers don’t like the spaces, nor do homeowners, although a properly installed baseboard –one that’s mounted after the floor goes down – should cover the space.
While Lummer says most of the floor failures he sees can be chalked up to either a lack of expansion joints or improper preparation of a cement substrate, he’s seeing more and more instances where stone-tile floors are failing after being installed over wood – such as for second-floor master bathrooms.
The problem, hard as it is to believe, is that natural stone, unless it’s at least 1 1/4” thick, lacks the structural integrity of a ceramic tile.
Lummer says this typically happens because the tile installer goes in and does the job without properly evaluating the subfloor that’s been previously installed. That’s a critical error because the TCNA calls for 19/32” plywood to be installed, and the American Plywood Association spells out how it’s supposed to be put down.
“The guy will go in and put 1/4” backerboard in there, or he’ll put in wire and float it,” he says. “With stone less than 1 1/4” in thickness, the sub-floor will need to be beefed up to what is called for in the TCNA Handbook. Deflection of ceramic tile is L/360 under a 300 lbs concentrated load; for stone it is double that—L/720.”
Mowat says he was called out to inspect such a failure just recently.
“The backerboard installed was not proper, and now they have 2,000 ft² of Durango travertine where you can walk in and see the indent fractures throughout the entire floor,” he explains. “You have to follow the proper installation instructions.”
While that’s sound advice on any job, Mowat adds that not all jobs install the same. He cites another recent problem he analyzed where it cost $165,000 to remove and replace a floor in a Los Angeles condo because the sound-rated flooring wasn’t installed to the manufacturer’s specifications.
While it might be possible to avoid doing it for a small bathroom or foyer, for larger jobs where stone tile will be installed over wood, Lummer recommends bringing in a structural engineer to calibrate the floor’s deflection.
It’s something he always does in his own business, he adds.
“At the end, he’ll tell me to add another thickness of plywood or add some piers every so many feet,” Lummer says. “He charges me $175-$225, and I won’t install a floor until he’s done the inspection.”

THE GOODS ON GROUT
While natural-stone tiles may lack enough structural integrity to create indent fractures on a poorly prepared floor, on many jobs the weakest link is the grout between the tiles. However, there’s weak – and then there’s weakest.
Halvorson relates one job where he was called out when the grout in a commercial installation came out in the bristles of the equipment used to clean the floor.
“It’s a little tough to explain that to the customer,” he says, adding that many failures of that type occur because the installer has over-watered the grout to speed up production and aid in clean-up.
“We have people who take a product and then modify it themselves,” Halvorson says. “We have all these creative contractors out there with their own hybrid methods and their own hybrid systems that don’t work.”
The MIA is adamant about that. In its Dimensional Stone Design Manual, it states, “Do not improvise on MIA and TCNA installation standards. There are as many homemade formulas for setting stone tiles as there are dimensional stones.”
Along with the chemically adventurous, both Halvorson and Lummer say many contractors don’t understand the importance of cover-curing their grout, so it doesn’t reach full hardness. Lummer, in fact, estimates he finds soft grout on nine of 10 jobs he inspects.
“It should be cover-cured for 72 hours, as required by both the American National Standards Institute (ANSI) and TCNA and referenced by MIA,” Lummer says.
Both men admit that most contractors are loath to go to the work of putting down craft paper and leaving it for three days, both because of scheduling and because the installers don’t get paid until the job is totally done.
However, even if the end result is just soft grout, Lummer says it can ultimately lead to unhappy customers because of what happens over time.
“If you look at it under a microscope, you’d see that it’s full of holes and pores that fill up with dirt,” he says. “It gets dirty because it’s porous. By comparison, if you look at grout that’s been cured for 72 hours, it’s so dense you almost never have to seal it.”
It’s also a problem not limited to floor tiles; Lummer contends poorly cured grout is why so few tile countertops are installed today.
However, grout problems are also often the most visible symptom that something else is wrong with the installation. For instance, Lummer says when grout joints turn white, it’s often a case of an improperly used latex thinset over a waterproof membrane, where water has gotten under the tiles and the latex re-emulsified.
“If you have plastic on the bottom so no moisture can go down and you put an impervious stone or tile above it, no moisture can get through it, except through the grout joints,” he says. “If there’s a little flood or something, you can lose the whole floor.”
When grout cracks or fails, Mowat says other reasons may be more-common. For instance, in one recent job he analyzed, pulling the tiles showed the slab underneath had cracked. In another, the baseboards had been installed before the tile went in, leaving the job with inadequate expansion and perimeter isolation.
“A cracked grout joint is a symptom of expansion or contraction underneath the tile or of the tile itself,” he says. “It’s also a sign you have a progressive loss of bond.”
One of the easiest ways to reduce these problems is to choose one source for mortar, thinset and grout, and then use them as the manufacturer recommends, says Halvorson.
“Know the system you’re using, know the methods you’re using and research the manufacturer’s data,” he says. “If you have all your eggs in one basket and something goes south, you’ll have somebody to work with you. You’ll have a better warranty and better control.”
Of course, knowing a system is only one small aspect of what a tile contractor should know to avoid costly mistakes. Lummer says studies have shown very few people in the trowel trades have formal training. Those who don’t can pay for their mistakes the hard way, or they can do something to decrease their chances of needing a lawyer and a forensic specialist.
“Contractors need to have continuing education,” says Lummer. “They need to be familiar with the TCNA and MIA standards and with ANSI, and they need to be reading and taking seminars. Materials change, products change, and they need to learn what the trends are and what’s going on.”
Mowat agrees. He says he belongs to more than 50 different associations, and organizations such as the National Tile Contractors Association have excellent materials available to members.
It sounds like a lot of work, but if you’re doing these jobs, it can be the best investment you make because so much has the potential to go wrong, says Lummer.
“Remember, it only takes one failure,” he says, “to wipe you out.”

This article first appeared in the March 2007 print edition of Stone Business. ©2007 Western Business Media Inc.