How to tell if your apartment has mold (and how much it will cost to eliminate)

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New York City prewars are renowned for their old-school charm, and new construction apartments for their modern flourishes and amenities, but neither are immune to the problem of mold. 

Steve Wagner, an attorney with Wagner Berkow (FYI, a Brick Underground sponsor), tells us he’s seen an uptick in lawsuits involving mold recently, with lacking remediation usually the cause for contention.

"The age of buildings is increasing, and water seepage is more prominent," he says. Plus, "people are far more aware now of what’s needed to remediate, and the danger of living in a building where mold isn’t properly remediated."

[This article was originally published in 2010, and was updated with new information in November 2016 and September 2017.]

Meanwhile, Jeffrey Gross, a water damage and mold remediator at Maxon's Restorations, a Manhattan restoration company, reports that his company deals with newer buildings with mold problems more than older ones.

"We respond to plenty of leaks and occurrences in old and new buildings," he says, "but I think we do more mold remediation in newer buildings."

The reason: "Newer buildings don't breathe as much, and if there is some kind of leak or water damage, mold can grow." Older buildings have fewer materials that mold can grow on, whereas engineered flooring, sheetrock, and processed materials are "junk food for mold," he says.

If you're buying in a new building with mold, chances are you won't have much recourse, with the developer, anyway.

"It is unlikely unless the mold is there and either (a) the sponsor knew or should have known and didn't disclose—in which case the [attorney general's] office" could get involved—"or (b) the sponsor actively and fraudulently concealed it or contracted with the purchaser to get rid of it, in which case the purchaser would have" the basis for a lawsuit, Wagner says. 

Gross adds, "If you clogged your toilet, you have no recourse with the developer, but if the mold was a result of a poorly designed building system or a construction shortcut then you would."

If you're renting, you shouldn't have to pay for maintenance, experts say.

"A renter can force his/her landlord to remediate through housing court," Wagner says. A case "can be brought, or the tenant can withhold rent and ask the court for an abatement of rent, and to compel the landlord to remediate."

Top 3 sources of mold

Gross says there are three main scenarios for the proliferation of mold in new and old NYC apartments:

1) Leaks from another apartment

Broken pipes and water overflows can soak your ceiling and walls from above, or seep into your floors and walls from the side. The most common offender: Plastic water supply lines to sinks and toilets, which newer buildings tend to use more. (Tip: Copper, which older buildings tend to use, almost never leaks, Gross says. Galvanized steel is another sturdy material in this regard.)

Treatment: If, for example, your upstairs neighbor's toilet or shower overflows into one room of your apartment, your ceiling and walls would be affected. Professional water remediation—which involves drying out the area behind the wall to prevent mold—costs about $1,200-$4,000. That process takes about 3 to 10 days and includes sucking up the standing water, making holes in the wall to ventilate the wall cavities, possibly pulling down a light fixture to get air into the ceiling, cleaning and treating all surfaces with an antimicrobial agent, and setting up drying equipment.

If mold is present and the affected area exceeds 10 square feet, the New York City Health Department guidelines require a full-scale mold remediation by a trained and qualified professional like Gross. Since 2016, New York state has required mold remediation companies to be licensed. The new law also makes it illegal for companies to do both testing and remediation (Gross says his company will recommend two or three companies for testing mold when clients call about this).

Expect the fee to run $8,000-$15,000 for a full mold remediation. And since many insurance policies exclude mold these days (more on that below), you may wind up paying for all of this yourself if you're the owner.

2) Clogged PTAC units 

These all-in-one heating-and-cooling units, located radiator-style against the wall, are a huge blind spot for NYC apartment owners in newer buildings, who tend not to realize that PTAC units require twice-yearly maintenance, and that as the owner of the apartment, it’s their responsibility, says Gross.

"If you rent in a condo, your landlord (the unit owner) is responsible for maintenance," he explains. "If you are in a rental building then the landlord is responsible for it, but in those cases there is usually a building-wide maintenance contract. The blind spot is the 'amateur landlord,' a person who buys a condo for investment and then rents it out." 

"If the 'amateur' landlord is not responsive to a complaint and if the apartment was purchased for investment, or the purchaser is a holder of unsold shares or of unsold units, the apartment owner is required to have the same managing agent as the building so the tenant knows who to  call for a repair or to lodge a complaint," Wagner says. "That doesn't mean the building's manager will arrange to fix it, but at least there is a place to lodge the complaint and the tenant knows it will be passed along."

"The most common occurrence with the PTAC units is that the filter is not replaced often enough," Gross says. "Dust collects on the filter and on the coils, and through condensation it drips into the condensate pan and clogs the drain. Then the condensate pan overflows and leaks under the floor. And also people forget to clean them after doing renovation where there’s a lot of dust.”

Unfortunately, dripping PTAC  units tend to cause mold more often than other types of leaks, says Gross, because they leak so slowly into the floor that it’s not noticed until a large section of flooring shows damage. Nearby sheetrock can also be impacted, as it wicks up the moisture from the floor.

Treatment: If you are lucky enough to catch the leak soon after it begins, cleanup may just involve removing a few floor tiles, removing the base molding and drilling a hole to dry the wall cavity. This can run between $800 and $1,500 and require minimal repairs.

When mold is present, situations like these nearly always require a full-scale mold remediation as they tend to exceed the Department of Health’s 10 square feet rule. Remediation typically involves ripping out a few square feet of floor, sheetrock, and base molding to get rid of mold. Average cost is around $6,000, plus the cost for a contractor to come in and repair the area afterward.

3) Broken washing machine hose 

"We get a lot of these," Gross says. "When you buy a washing machine, even the fancy ones, they install them with inexpensive rubber hoses. Those are the ones that break, as opposed to the less-than-$30 stainless-steel-wrapped hoses you can buy at Home Depot that almost never leak."

Treatment: “If we come in right away after the leak is caught, we’ll vent the wall cavities, pull the base moldings off, drill holes, and get air movement into the wall cavities to dry them," he continues. "If there’s a wood floor, we may try to dry that too, unless it’s already showing evidence of buckling and cupping."  

For one room, he says, the cost is around $1,200-$5,000. If mold has already set in, a full-scale remediation would entail removing the flooring and base moldings, cutting the sheetrock walls up two feet around the perimeter of the room, then treating as described below. Price: $8,000-$12,000.

How to tell whether you have mold in your apartment

How do you know if you have a problem? It’s not always obvious, says Gross.

  • Water damage: You'll probably notice water damage and staining before you notice any signs of mold, because mold tends to grow faster inside the wall than on the surface. That’s why it’s important to address any moisture problems quickly.

  • Odor: One of the first signs that mold might be present is a wet, musty smell or the smell of moldy, wet building materials. These indicate a moisture problem that can lead to mold; it doesn't necessarily mean you have mold.

  • Spots: Black, gray, green or brown spotting. Only testing can prove whether or not it’s mold, but if you see spotting on a surface like sheetrock that is or was wet, it’s worth testing, Gross says.

  • Health problems: Respiratory reactions including asthma are most common, though mold sensitivity can also cause headaches and skin rashes. Some people have symptoms immediately. For others, it develops over time. Note that not all types of mold cause health problems. To identify which type of mold you have, an industrial hygienist will need to collect a sample for testing.

Anatomy of a full-scale mold remediation

Full-scale mold remediations in New York City apartments typically cost around $8,000-$15,000, according to Gross. Unless your insurance excludes mold—many policies do—it will be covered if caused by a "covered event" like a pipe break or overflow from upstairs.

"Mold is usually limited or excluded" from insurance policies, explains Jeff Schneider of Gotham Brokerage (also a Brick Underground sponsor). "Immediately after a covered water-damage claim—like a burst pipe or an overflow of a sink or toilet—the polices will generally include coverage for clean-up, drying, and steps to prevent the growth of mold. But if water is not cleaned up or if an area is missed, a resulting mold situation in the future will typically not be covered, or if covered, will be subject to strict limits. And a mold situation that occurs from just general damp conditions would typically not be covered at all.”

So, if you have a water damage situation, search for all the wet areas.  

“Water can travel to unexpected places,” he says.

And when you have found it all, he adds, "Do a good cleanup."

(For more information on insurance coverage of mold claims, check out our guide here.)

To understand why your handyman probably isn't the best person for the job of removing mold, here’s Gross’s rundown of what goes into a full-scale mold remediation:

  1. Containment of the work area: "Mold is a living organism, and when you disturb it kicks off spores into the air, so we seal off the work area by building a tent of [plastic] sheeting around it to prevent cross contamination."

  2. Negative pressure of the work area: "We exhaust the work area through HEPA filtration, usually to the outdoors. That basically puts the area in a vacuum—the negative pressure prevents mold spores from migrating out of the work area into the rest of the apartment while we’re working."

  3. Removal of contaminated materials: "It’s more of a surgical removal than a demolition. We don’t use sledgehammers—we use knives and spray bottles to wet down the material. The debris we create is bagged in [plastic] bags taped shut, and the exterior has to be vacuumed to prevent cross-contamination. Surfaces that can’t be removed, like a concrete slab, have to be cleaned and if there is evidence of contamination, have to be encapsulated in an antimicrobial sealant, like a primer."

  4. Cleaning: "We assume the entire work area is now contaminated.  All surfaces must be cleaned in a three-step process—HEPA vacuuming, damp wipe, and HEPA vacuuming—sometimes called the HEPA sandwich.  We also scrub the air—air is filtered over and over again through HEPA filtration, at least four air exchanges per hour for 12-24 hours."

  5. Post-remediation verification: "An industrial hygienist will come in and take air samples of the work area, the area beside the work area, and the outdoors to compare them to each other and to pre-remediation tests, if any, to determine that the mold levels in the work are have returned to normal."

If you are think you have mold, you may want to contact a certified industrial hygienist to take air samples, perform a survey, and devise a clean-up plan. Beware of remediation companies that offer "mold fogging" or filling wall cavities with spray foam, rather than full removal of the contaminants.

And again, "Remember that it’s illegal for a company to do both remediation and testing," says Gross. "You always want an independent third party, preferably an industrial hygienist, to perform air testing."