These illegal units are often less expensive and enticing to low-income New Yorkers, struggling to find affordable units in the midst of the city's affordable housing crisis.
A recent NYC housing report estimated the city has more than twice as many low-income households as it does available affordable units.
Additionally, 7 On Your Side Investigates found most of the tenants who end up in these units have no idea the apartments they are renting are illegal and unsafe.
7 On Your Side Investigates went undercover and found illegally converted apartments in basements and attics with questionable plumbing, gas lines and electrical lines.
Those renting the units are at risk of unannounced, immediate evictions from the New York City Department of Buildings due to safety concerns.
Tenants in the illegally converted units have encountered shoddy plumbing that led to significant water damage and mold, cramped conditions and in the worst of cases, several tenants have died when their units caught fire and lacked mandatory fire escapes.
"I was sleeping here last night and all of a sudden I have to go," said Mohammed Islam one weekday evening in late January, while he was getting evicted from the attic apartment he and his family had been renting for about a $1,000 a month in Queens.
Inspectors with DOB discovered the illegal unit the Islams were renting, along with several illegally converted units in the home, after firefighters responded to the house on 72nd Street to correct a potentially dangerous gas leak.
GRAPHIC: Clues your apartment is illegal
Last year, 311 averaged more than two complaints an hour about illegal apartments, according to data obtained by 7 On Your Side Investigates.
According to DOB, inspectors issued 2,523 violations to property owners in 2017, a 13-percent increase over the prior year citywide, with the problem particularly bad in Queens. There, landlords received nearly as many violations as property owners in all of the other boroughs combined.
"It is kind of frustrating to know that you may be potentially telling someone that they cannot live anymore in the apartment they called home," said DOB Inspector Listoriel Vasquez. "At the same time, when you put safety first you can process all the other obstacles in that particular situation."
7 On Your Side investigates responded to questionable Craigslist ads and caught one landlord trying to rent two basement apartments that had already been the subject of two prior complaints about illegal units to DOB.
Residents caught living in these units are issued vacate orders due to safety concerns. The city offers to connect them to the Red Cross and housing counselors to assist them in finding a new place to live when they have nowhere else to go.
"If I at least assist them into a safer location, they have less potential of risk to their own safety and their family's safety," Vasquez said.
Landlords caught renting illegally converted units can face multiple violations with fines, at times, reaching $25,000 each.
In the past, property owners who repeatedly break the law have also faced criminal charges for endangering the lives of tenants.
Vasquez said the city is working to crack down on the increase in these problematic units.
"It's just been a major increase," Vasquez said.
The landlord in Islam's case declined comment despite repeated efforts by 7 On Your Side Investigates to discuss the violations.
DOB offers several tips to renters to help them avoid renting these dangerous units.
Vasquez said tenants should be wary of basement and attic apartments, as well as units with small windows or no windows at all.
Vasquez also said to avoid units without two separate exits out in case of a fire and cautioned renters from moving into units where all utilities are included. Vasquez said those buildings often include utilities because the buildings are not authorized for multiple tenants.
Prior to signing a lease, prospective renters can also view the building they are considering on the DOB website by entering the address in a grid that reads "Buildings Information" to check for any outstanding violations and view the certificate of occupancy to determine how many units the home or building is authorized to have.
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