When we last met up with Jeffrey Tubbs, he was two years into his first building project and doing well, though it was 2010 and we were still mired in the real estate downturn.

Four years later, Tubbs is still small and successful but growing, combining youth - he's 37 - with enthusiasm.

Part of his success stems from building for-sale housing the next address up from "the hot neighborhood" - in this case, Northern Liberties.

We're seeing a lot of activity like that in Philadelphia these days, although much of it is rental as developers large and small retrench after squeezing through sales gates as they were closing shut.

In fact, as I reported a few weeks ago for "Town by Town" in the Sunday Business section, single-family rental development is hot in Northern Liberties, which has local leaders concerned about the long-term effects on the neighborhood as it emerges from the downturn.

Tubbs and his associates - including Robert Shaw, whose family was involved in the St. James and the Murano - are not eschewing the rental market. Just the opposite, since there are rental and commercial components to one project in the planning stages - "we're being flexible," he says.

In 2008, he started building the Flats at Girard Pointe at Third Street and Germantown Avenue in Olde Kensington, just above Northern Liberties.

That eco-friendly project of five townhouses and four condos, situated on an 8,000-square-foot lot bought from the city Redevelopment Authority, commanded prices of $300,000 to $450,000.

One townhouse was his, because Tubbs says that to be successful a developer has to prove his commitment to improving a neighborhood any way he can.

Today, at American and Thompson Streets, one block from the Flats at Girard Pointe, Tubbs and his JDT International are starting a five-unit, for-sale complex with one single-family house, three condominiums, three off-street parking spaces, and a new office for his real estate business and his nonprofit Urban Roots.

"We just received our zoning approvals for this, and close on our construction loan and begin in July," Tubbs said, adding that he'll be moving there.

He also is building three single-family houses at Amber and Abigail Streets in East Kensington.

Tubbs' buyers are the usual suspects: "Young professionals, first-time home buyers, creative people from Brooklyn looking for more space for their money," he said.

The neighborhood is right on the Market-Frankford Line, 15 minutes from Center City and 20 minutes from 30th Street Station, he said.

In the 2000 block of Frankford Avenue, across from the Rocket Cat Cafe, Tubbs owns two adjacent parcels that make up a 12,000-square-foot lot - 9,000 of which were purchased from the Redevelopment Authority - that "will be a combination of condos and rentals in phases and adaptable to market changes," he said.

Urban Roots is Tubbs and Shaw's effort to enhance their redevelopment projects with art, design and sustainable features while mentoring neighborhood youth.

A manifestation of that effort is the Urban Topiary - 100 digitally fabricated, galvanized-steel tubes that provide a spiraling armature on which flowering vines and ivy can grow. It more than fulfilled the Redevelopment Authority's 1 percent art requirement.

Urban Roots also participating in a "sculptural miniature golf course across the street from our project that will be an amazing artistic amenity," involving Little Baby's Ice Cream, the local community-development corporation and Tyler School of Art, he said.

"There is so much cool stuff going on in this neighborhood," Tubbs said.

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