In five months, Philadelphia’s controversial 10-year property tax abatement will be no more. So could a lot of fine old buildings from the 19th and early 20th centuries.

The lucrative incentive, which helped fuel a decade-long construction boom, is set to expire at the end of the year, when it will be replaced by the equivalent of a five-year tax break. Because developers must have an approved building permit by Dec. 31 to qualify for the 10-year abatement, preservationists worry that we could see a rash of tear-downs as they rush to clear their sites and ready their projects for construction.

In the last week alone, demolition notices have gone up on three noteworthy properties: the historically designated St. Laurentius Church in Fishtown, two early 20th-century banks in Kensington, and two rowhouses on a beautifully preserved, 19th-century block in Powelton Village. Those notices come after a season of heavy destruction that has taken a Romanesque-style Catholic church in West Philadelphia’s Haddington neighborhood, a severely damaged, but still magnificent synagogue in Strawberry Mansion, a handsome industrial building on Spring Garden Street, the historically designated home of a notable 19th-century painter in Germantown, and a slew of elegant 19th-century townhouses on the stretch of Christian Street known as “Black Doctor’s Row.”

As one of America’s oldest cities, Philadelphia has such an extensive collection of 18th-, 19th-, and early 20th-century structures that the disappearance of a rowhouse here, or an old church there, might not seem to meaningfully change the look of the city. Many of the tear-downs, like the former Downey’s restaurant on South Street, are simply well-crafted and well-loved masonry buildings that probably wouldn’t qualify for historic status.

But after more than a decade of intense development, it feels as if the losses are starting to add up. On streets where Philadelphia’s sturdy redbrick houses were once ubiquitous -- like Ridge Avenue in Francisville or Front Street in Fishtown -- flat metal panels are becoming the dominant vernacular. The demolition targets increasingly include designated buildings, which are supposed to be protected by the Historic Commission but are flagrantly neglected by owners who have little fear of official sanction. City Hall sets the tone with its willingness to destroy its significant modern designs like Fairmount Park’s Carousel House and the Columbus Square pavilion.

The 10-year tax abatement can’t be entirely blamed for the demolitions. Housing demand has remained consistently strong for more than a decade, even during the worst of the pandemic. Interest rates remain low and many buyers prefer new houses over older ones. But as Paul Steinke, who runs the Preservation Alliance, observes, the city’s “development policies are geared toward demolition and replacement. This is all happening in a city with an abundance of properties that could be restored.”

The coming changes to the tax abatement are meant to partially redress that imbalance. While new construction will be eligible for what adds up to five years’ worth of tax breaks, renovated properties will qualify for 10 once the new law goes into effect in January. That incentive is one of the few concrete measures to emerge from Mayor Jim Kenney’s preservation task force. Yet a variety of other zoning bonuses, which allow developers to construct taller buildings, could still tip the scale in favor of demolition.

While each of those bonuses was established to further a worthy goal, they have produced unintended consequences. The mixed-income height bonus was created to offset the impacts of gentrification and provide funds for affordable housing. The green-roof height bonus is designed to help manage the runoff from heavy rain and support the city’s sustainability goals. The problem is that they also drive tear-downs by allowing developers to build bigger structures with more units, thus enabling them to extract more rent from the same piece of land.

That’s exactly what’s happening on the 3700 block of Lancaster Avenue, a syncopated ensemble of 19th-century brick houses with small shop fronts on the ground floor and identical roof cornices. Although the row is in near-perfect condition, a developer intends to yank out two properties in the exact middle, cleaving the block in two. Using both the mixed-income and green-roof bonuses, the developer plans to build a 16-unit apartment complex. The midblock demolitions, similar to the ones on Christian Street, are becoming increasingly common around the city.

Many development advocates argue that such projects increase the city’s housing supply and keep rents from rising too fast. They are not entirely wrong in their economic analysis, but they grossly undervalue architecture’s contribution to Philadelphia’s soul. Those ensembles are what help give the city its identity, bind us together as citizens, and make our streets such an interesting place to walk and bike.

When City Council established the tax abatement in the late 1990s to encourage conversions of mothballed office buildings, it almost certainly did not intend for it to be used to destroy intact and inhabited buildings. Every time an inhabited building is demolished to make way for new construction, someone gets displaced and must hunt for new housing.

In the case of both Lancaster Avenue and Christian Street, an increased number of units could be achieved within the existing structures by adding several new floors. Even if the developer merely saved the facade and inserted a new structure behind the old walls -- known as a facadectomy -- it would be better than demolition.

Such a compromise could end up saving the two old banks on Front Street, according to David Neff, a public relations specialist who represents the owner. Neff would not reveal the developer’s identity but said the company has hired Canno Architecture to design a facadectomy or overbuild similar to the one they executed at Stable Lofts on North Broad Street. Neff said the developers sought the demolition permit “as a matter of preparedness” in case the project doesn’t work out.

It’s not clear whether the twin-spired St. Laurentius will be so lucky. The church has been neglected for years, yet it has always managed to evade the wrecking ball. But after its towers were deemed unsafe last year, the Historical Commission gave the owner, North Jersey’s Humberto Fernandini, permission to remove them. Nothing changed until the demolition notice was posted last week.

I reached out to Fernandini via LinkedIn and a lawyer who represents him in other matters, but he did not respond. I also sent a query to Jon Farnham, the executive director of the Historical Commission. Based on his lengthy and convoluted response, which referenced a long list of city procedures, it appears that Fernandini will take down the towers but not demolish the entire church. But it’s hard to know for sure.

Mayor Kenney came into office vowing to improve the treatment of the city’s old buildings, and his preservation task force spent 18 months exploring the issues. There have been several major saves, including the Metropolitan Opera House on North Broad and a gorgeous limestone bank in Kensington. “Mayor Kenney has consistently said that he prefers adaptive reuse to demolition,” a city spokesperson wrote in an email.

But a look at the city’s database on building demolitions shows that the number of tear-downs has remained remarkably consistent since the start of Kenney’s administration. The monthly totals topped out at 117 in January 2017, as he started his term. They hit a low of 29 demolitions in July 2020, during the depths of the pandemic.

This July, the number of demolitions was back up to 75. Unless officials start taking preservation seriously, it seems, Philadelphia will continue to lose its architectural heritage, bit by bit.