950 Marlborough StUnder construction

A five-story, 26-unit building is under construction at 950 Marlborough Street in Fishtown, cleared to build late last year on a roughly 6,100-square-foot lot. The project will employ a split construction approach—heavier Type IA for the basement and first floor, lighter Type VA wood framing above—connected through horizontal separations that technically create two buildings under one roof. Amenities include a common roof deck, accessory parking, and full sprinkler and standpipe systems, with an amendment approved in May 2026 updating the foundation design.

The site sits in an RSA5 zone, which permits multifamily construction by right at this density, and was acquired in 2024 by 1212 North Delaware Avenue Qoz LLC. The ownership entity signals a likely link to the opportunity-zone-fueled development wave reshaping this stretch of Fishtown, where developers have tapped federal tax incentives to assemble infill parcels and push five-over-one construction into formerly industrial blocks.

The Marlborough project lands amid one of the neighborhood's densest development corridors, with nearly 800 units either delivered or in the pipeline within a half-mile radius. That cluster includes the 182-unit tower at 1130 North Delaware, a 107-unit building at 1122 Frankford, and several other mid-rise projects along Delaware Avenue and Frankford Avenue. The scale here is more modest, but the parcel size and zoning fit a pattern: small lots along secondary streets getting penciled into rowhouse-replacement multifamily as larger assemblages take the arterials.

What's notable is how quickly RSA5 has become the default tool for filling in the edges of Fishtown's grid. As Delaware Avenue and Frankford continue absorbing hundred-plus-unit projects, side streets like Marlborough are seeing 20- to 30-unit buildings slot into lots that once held single garages or shallow industrial sheds. The economics clearly work at this scale, and every similar parcel within walking distance of the riverfront is now a candidate for the same treatment.