By K. Schipper
HOUSTON – This is an industry that loves to talk about how durable natural stone is. And, it is — at least under normal conditions.
Throw in the record rainfall and resultant flooding of one of the major weather events of the summer, Hurricane Harvey, and a lot of building managers and homeowners are finding their travertine, granite, limestone and marble can be just one more problem to be dealt with in a long list of issues that has to be resolved before life returns to anything approaching normal.
Harvey caused damage in a huge curving path from Barbados in the Caribbean to North Carolina in late August and early September, but the major impact came along the Texas Gulf Coast. The storm loitered for more than 60 hours, dumping between 30” to 60.58” of rainfall. (The latter number, recorded 90 miles east of Houston in Nederland, Texas, is the greatest single-storm rainfall in U.S. history.)
The Houston metropolitan area bore the brunt of Harvey, with an estimated 25% to 30% submerged at some point during the storm. The water that came – and stayed – caused an estimated $150-billion-plus in damages, including plenty of natural stone floors and other surfacing.
Granted, it’s often not the stone’s fault. Whether it’s the lobby of a skyscraper or the custom shower in a master bath, the drywall behind the installation is a big part of the problem. As soon as the water receded, demolition crews were busy removing that soggy mess to keep mold from growing.
It might be easier to assume that stone floors would make a better showing, since most are installed over concrete with a mud bed. However, days, even weeks, of being covered by water make for serious issues.
Jacqueline Tabbah, vice president of International Stoneworks Inc., which specializes in natural-stone restoration and maintenance, says many of the problems she’s been called in on since Harvey have been underfoot.
“A lot of my job has been just consulting on whether or not the floor needs to be replaced,” she says.
As of late October, Tabbah estimates she’s been called to more than 50 different floors, and the problem she says looms largest is that it’s impossible to evaluate what’s going on under the stone floors based on what they look like from the surface,
Look closely at the left leg of this fireplace, and the coloration changes about a third of the way up … that’s the floodline in this Houston house. (Photos courtesy International Stoneworks) 
While this is Saltillo tile, it shows the effect of a topical sealer on the surface that inhibits moisture evaporation, and encourages efflorescence. 
A double-dose of problems with gray flamed granite: moisture discoloration and efflorescence. 
Residential terrazzo floor after water receded.
although there are other professionals who can properly evaluate levels of moisture.
The biggest issue for the entire area in the wake of the storm was — and remains — mold. Even after removing ruined drywall and furnishings, Tabbah says she can’t ascertain whether the floors are completely dried-out.
“I have a surface moisture meter, and all the floors I’ve seen, even weeks after the storm, are indicating there’s still moisture within the pores of the stone or tile,” she says.
Once Tabbah can get a good look at the floor, she says she’s finding a variety of issues. In one case, she says her initial inspection of a travertine floor suggested it was merely dirty.
“Then, the client said, ‘See the cracks in the floor? They weren’t there before the flood; they’re new,’” she says, adding it’s not a problem her company could address through stone refinishing.
In another case, she said the client had a grey granite floor with white marble strips running through it that had turned brown.
“We didn’t know if the marble was stained all the way through or if it was just gunk on the top,” Tabbah says. “We did some testing and it did lighten up significantly.”
She adds that the clients are planning to keep the granite, but at last report were still debating the fate of the marble. Often, as a floor completely dries, stains will lighten.
Where they don’t, Tabbah says one option is to apply a poultice to help draw out the stain.
However, as a floor is drying, it may also show patches of another problem: efflorescence.
Tabbah says she’s seen that primarily in slate, flagstone or Saltillo tile floors that have a coating of some sort on them – anywhere from wax to a polyurethane sealer – that keeps the moisture from completely evaporating. The first step, obviously, is to strip the sealer off the floor.
“It can be tricky to remove those calcium deposits,” she says. “If you have a marble or limestone or travertine surface, you can’t use acid cleaners because they’ll etch the stone. In those cases, we use several honing methods to remove the buildup.”
Over at Camarata Masonry Systems Ltd., the story has been similar, although the clients are frequently much bigger. Camarata specializes in large commercial installations, and was honored this year with both a Pinnacle Award and a Coverings Installation and Design Award for its work on Houston’s Energy Center III.
Ron LaRicci, Camarata vice president, says fortunately that particular building didn’t suffer beyond water damage beyond the parking garage and garage-elevator lobby. Some of the company’s other projects in the same area weren’t as lucky.
He explains Camarata has been called in to help resolve issues with stone in four separate buildings in the Houston Energy Corridor, all of which suffered flooding when the Addicks Reservoir had to be opened.
As of late October, the company assisted in removing the stone from lobby walls and, in some cases, floors. LaRicci will be heading to Europe for one owner to review replacement stone for damaged lobbies.
Before Hurricane Harvey, natural stone dominated the lobby at Houston’s Enclave Place, including a generous use of Texas limestone. (Photo courtesy Piedmont Office Realty Trust) 
In that same lobby post-Harvey, the lower-level stone came off to replace damaged drywall; the Texas limestone will be cleaned and reinstalled. (Photo courtesy Camerata Masonry Systems) 
In another building, the floor-to-ceiling stone cladding in this Houston lobby came out after flooding ruined the bottom 8′ of drywall. The owner opted to select all-new stone for replacement (Photo courtesy Camerata) 
This used to be very white marble; moisture underneath the surface now gives it a grey cast. (Photo courtesy Camerata)
While it’s possible some wall stone can be rehabilitated, he doesn’t hold out much hope. For instance, in one building, water rose more than 3’ on limestone lobby walls.
“The limestone is probably done, just because of the crud that was in the water,” he says. “It gets in the stone; now you can’t get it out, or it’s more-costly to attempt to clean the stone.
“We also elected to replace a bunch of marble floors. They had been submerged for over two weeks, and we had no idea what impact that would have on the integrity of the setting bed.”
Much of the granite could be salvaged because of its density, although it would require time to thoroughly dry and then any remaining stains will have to be cleaned individually. And, if it’s not salvageable, LaRicci says typically it’s easier to match existing granites than it is for marbles and limestones.
However, on one limestone project, Camarata Masonry has been asked to attempt to match what’s still standing.
“We can get a few pieces, but you can definitely pick out the new stones once they are installed adjacent to the existing ones,” he says. “However, it’s what’s available at this time, and we can only do the best we can.
“This is a case where the insurance company does not want to pay for replacement of all the stone.”
In general, both Tabbah and LaRicci say it’s going to be awhile before their hometown is back to normal. LaRicci, for instance, notes that the floor in one of the two buildings for which he’ll be traveling to Europe to select new stone is still in place and will stay put for the immediate future.
“It used to be a very white marble floor, but there’s moisture underneath that’s giving it a dark grey tint,” La Ricci explains. “I’ve recommend that they remove it now, but they don’t want it removed yet, and I think they’re going to try to open the building back up before the replacement stone arrives in early 2018.”
LaRicci says he also knows this stone can’t be reclaimed. Earlier in the building’s history, there was a leak of potable water and it took several months and a lot of work to get it back in acceptable condition. It will only be worse with the introduction of storm drainage water and all its contaminants.
“We also heard that there are now quite a few scratches and gouges on the floor from drywall screws and other objects that were dropped while performing moisture remediation,” he says. “They tried to protect it, but it’s a white marble, very soft and easily scratched up.”