The DOB's Quality of Life division follows up with complaints on illegal subdivisions, like this home in Corona which housed 27 people. View Full Caption DNAinfo/Katie Honan

CORONA — The number of vacate orders issued to homes with often-dangerous illegal conversions has dropped by more than half in the past three years, according to the Department of Buildings.

In 2012, inspectors from the DOB's Quality of Life Unit, who investigate illegal conversions, issued 1,032 vacate orders to owners of units that had been illegally subdivided into a warren of smaller apartments, according to the department — shutting down life-threatening partitions like the one that led to the deaths of two firefighters during the "Black Friday" blaze of 2005.

The number of vacate orders dropped to 1,012 the following year. By 2014, that number dipped to 911. And in 2015, inspectors sent out only 630 vacate orders, although DOB officials said the number could change as more complaints are processed.

A DOB spokesman blamed the drop in orders to vacate — which were accompanied by a drop in the overall number of inspections — on a number of veteran inspectors retiring, as well as a change in approach.

“The Quality of Life Unit, which is primarily responsible for investigating illegal conversions, went through a staff shift last year resulting in a number of long-time inspectors moving into different roles or retiring,” the spokesman said in an email.

“Additionally, where possible, we are encouraging owners to correct illegal conversions without evicting people from their homes — issuing vacate orders only as a last resort when conditions pose a danger to the life of a tenant.”

The number of inspectors has actually risen since 2012, from 364 that year to 412 in 2015, according to the DOB. But some of those new hires are still in the process of getting trained, the DOB spokesman said.

The agency hopes to hire 100 more inspectors in 2016 with an “unprecedented investment of $120 million” in the DOB by Mayor Bill de Blasio, the spokesman said.

Illegal conversions of apartments and homes are monitored throughout the five boroughs, but most of the enforcement has happened in Queens, records show.

In 2012, there were 8,889 complaints filed in Queens. By contrast, Manhattan had 1,023, Brooklyn had 5,127, The Bronx had 2,079 and Staten Island had just under 1,000.

The percentage remained steady throughout 2015, when there were 8,382 complaints files in Queens compared with only 870 on Staten Island.

The majority of vacate orders issued across the city — which dropped from 71 percent in 2012 to 66 percent in 2015 — also came from Queens, according to data.

Inspectors take a more "aggressive" approach in Queens to fight the problem, an inspector said in 2014.

In extreme cases, the DOB needs a warrant to fully inspect and shut down a home. Nearly all of those warrants come from Queens, the inspector said at the time.

Last September, the DOB emptied an illegally subdivided house in Corona after a 15-year struggle.

Officials said 27 people from eight families, including 13 children, were living in subdivided apartments inside the two-story home.