A Brooklyn apartment building has become the most expensive slum in New York, residents claim.

Several residents of the battered Bushwick location on Starr Street say they pay nearly $4,000 a month to live with rat droppings on the countertops, moldy ceilings and leaky ceilings in the trendy neighborhood — prompting them to form a tenants’ association to fight the alleged slumlord who owns the place.

Hunter Boone, 34, started Starr St. Union a month ago after repeatedly calling 311 because of the dilapidated and sometimes “unlivable” building conditions in her $3,500-a-month two-bedroom apartment.

Boone said he and his dog even both contracted a parasitic infection from the nasty conditions. In May, the two suffered long-term digestive problems and were unable to keep food down due to exposure to rat feces, Boone medical records show.

“After that, that’s when I thought, OK, I really need to get the city involved in this rat problem. … If somebody’s charging that much, why does the building look like this? Wouldn’t that mean they’re quote-unquote a slumlord ? he said.

During a tour of the eight-unit building with The Post, Boone showed the shocking conditions — including rats dropping on his countertops, a condemned backyard, water-damaged ceilings and visible holes in his bathroom floor.

“This is a fire hazard here, these doors can’t close properly by themselves at the entrance. I actually printed my own ‘fire hazard’ signs for this,” Boone said, pointing to one of the building’s emergency violations.

Starr St. Union is taking organized tenants and legal action against the owner of Cayuga Capital Management Ventures, Jacob Sacks, who owns at least 21 buildings in the area.

His properties average two open city violations per housing unit, worse than the city average of 0.8 per unit, according to information from JustFix.

Only the Starr Street building has 49 open building violations.

When reached by The Post, Sacks defended his stewardship of the property, claiming there are only “four current tenants . . . who like to complain and deny access,” initiating the spate of complaints.

“The reality is that this is an activist tenant who you’ve seen is intentionally trying to inflate the problem and in the meantime prevent real repair work from happening,” Sacks said.

Boone says his nightmare began as soon as he rented out the two-bedroom apartment in April 2023.

The building is located across from a park and a few blocks from the L train line in the trendy North Brooklyn neighborhood.

And although online rental ads there show freshly painted rooms with stainless steel kitchen appliances, Boone said he soon realized the reality was far from idyllic when he heard rats scurrying in the ceiling that first night.

“When I mentioned this rat problem to the previous tenant, he said, ‘Oh, isn’t that just New York City?’ But you shouldn’t have rats in your roof, that’s crazy,” Boone said.

When Boone reported the problem to 311, Sacks tried to force him out of the building, even though records from Boone show he lived there legally, the resident claimed.

In December, Sacks told Boone he would only offer him a six-month lease for $600 more, bringing the total space to a whopping $3,500.

“At this point, all signs point to fraud,” Boone argued.

Boone couldn’t afford the move and paid the rent until he claimed it the heat stopped working and he was forced to live in 45 degree temperature. He also claims he had other problems, such as a backyard where the fence was in such poor condition that it was falling over.

“I thought this is totally crazy, I haven’t had heat in a month. … The city came and confirmed the apartment was 45 degrees, and the landlord immediately said, ‘Stop calling 311,'” Boone said

“But I told him this is crazy. I stopped paying the rent because I said, ‘I don’t have heat. I get to do this.'”

Sacks is now suing Boone in housing court for $12,300 for his unpaid rent and is seeking permission to evict him if he can’t pay, court records show.

But Boone says he’s using the case to expose Sacks to the city for the alleged neglect of his properties and win rent stabilization for the units in the building.

After a month of processing, the union has full participation from all eight units in the building.

With no resident superintendent, residents have resorted to going to the city’s Department of Housing Preservation and Development for their complaints.

A union member in the building paying $3,250 for a two-bedroom apartment described chaos when a pipe burst in his home, displacing his family for six days and forcing them to throw out all their groceries.

Although the leak was eventually repaired, and the man eventually received compensation from Sacks, mold spores are now visible on his roof, the resident claimed.

He also said the unit is overrun by vermin.

“I left a bag of groceries on the ground, and when I came back later, there was a hole chewed right through them,” said the tenant, who asked not to be identified.

One person has been seen on security cameras Boone installed in the building tearing down the Starr Street Union posters, photos showed.

Sacks denied tearing down posters, but Boone believes someone from building management was responsible, although there is no specific evidence that either was involved.

An HPD representative praised the Starr Street tenants for forming a union.

“The tenants at 147 Starr St have taken important steps to hold their landlord accountable by agreeing to address building conditions and filing complaints with 311,” the representative told The Post in a statement.

“HPD records show that the landlord has begun to make corrections, and tenants can object if they feel the problems remain unresolved, prompting another inspection by HPD to confirm.”

Despite the construction conditions, Boone said he has no plans to leave the apartment until he can resolve his case with Sacks.

“A lot of people in New York don’t think they can fight this kind of thing because it takes up so much of your f-king time,” Boone said

“I will now enforce my rights as a tenant, and I will fight this.”

Boone will go to Housing Court on October 30.