Better act fast: brownstones in Brooklyn are being snatched up like hot cakes.

Christabel Gough, the secretary for the Society for the Architecture of the City and a resident of the Greenwich Village Historic District, has a simple, to the point message for New Yorkers: Beware. Manhattanization, she warns, is growing, encroaching on historical neighborhoods throughout the five boroughs. It is the real estate equivalent of kudzu and Brooklyn, Ms. Gough says, is the next victim. Yet unlike it’s leafy cousin, Manhattanization cannot be eradicated with sheep.

But first, a word on Manhattanization, as explained by Ms. Gough in her keynote speech, “Can Cobble Hill Avoid Manhattanization” at the Cobble Hill Association General Meeting on May 29th, and helpfully reprinted at Brownstoner.

“How do you Manhattanize an old town house? First, you pay a seven or eight figure price to buy it. Then you destroy it—except, of course, for the street front, if it is in an historic district. You gut it. Your toss any Federal or Greek Revival woodwork into the convenient garbage scow outside the front door. You cut in new windows. You tear out the lower back wall. You change the floor levels. You remove some floors altogether to create double height rooms. That, your architect triumphantly explains, reduces your Floor Area Ratio! You expand the back with a rear yard addition; you expand the top with a rooftop addition; you expand underneath with new underground levels, which may include a swimming pool, a dog-grooming-room and other such essentials. If the swimming pool is of Olympic dimensions, you may ask to excavate the entire rear yard as well, turning the existing garden into a roof terrace. Your landscape architect and his arborist will testify that this will have no impact on the neighbors, because the roof of an Olympic-style swimming pool can be incredibly verdant and beautiful, when planted with trees with shallow root systems, such as crab apples! Or bamboo, perhaps. And your engineer will explain that of course there is no danger; excavation will be painstakingly monitored and the shoring will be state of the art!”

Ms. Gough is not the only Manhattanite concerned about this growing penchant for historical facelifts. “Many buyers re-entering the real estate market after years on the sidelines are discovering what they’re after in brownstone Brooklyn,” The New York Times’ Marc Santora recently wrote. The article, entitled “Brooklyn’s Gold Rush,” lists Brooklyn’s Fort Greene, Park Slope, Boerum Hill, and Red Hook as the most endangered neighborhoods. 

“Brownstones signify stability,” Jill Seligson Braver, an associate broker at Brown Harris Stevens, told the Times. “Putting roots down in a neighborhood for the long haul.”

But they also signify space.

“The current frenzy in the brownstone market is more a reflection of the continuing demand for large spaces,” Mr. Santora writes, and developers are increasingly snatching up two- and three-family homes and converting them into larger single-family residences.

As a result, the median sales prices of Brooklyn homes, once a much-welcome alternative to their pricier counterparts across the East River, have increased considerably. In Park Slope, median sales prices have jumped from $1.2 million to $1.45 million in the last year (a roughly 20 percent increase); in Boerum Hill, they’re up from $1.1 million to $1.7 million (a 60 percent increase); and in Red Hook, from $475,000 to $825,000 (a 73 percent increase).

Not since On the Waterfront has Red Hook been so popular.

jschiewe@observer.com