Stabilization of the teetering Girard Warehouses, the historic complex of early 19th-century buildings on North Front Street, has encountered "unanticipated problems," slowing repair work, a partner in the development project said yesterday.

BRP Development Corp., a New York City developer and the public face of the partnership that owns the historically certified commercial buildings, was required by an October ruling in Philadelphia Common Pleas Court to complete extensive repairs and sealing by the end of last month.

BRP yesterday asked for an extension of the deadline to the end of January. The developer plans to convert the complex to luxury condominiums.

Some neighbors have complained about the pace of repairs. Richard Thom, an officer of the Old City Civic Association, said there had been "minimal [construction] activity" around the building.

"We're heading into the worst part of the year with the worst weather," Thom said. "Why hasn't [sealing] started? It's not right."

Geoff Flournoy, a BRP cofounder, said that workers discovered that a rear wall of one building was unstable and that no foundation existed behind at least a portion of a rear wall that had previously collapsed.

New footings must be in place before reconstruction and sealing of the rear walls commences.

City officials, who met at the site yesterday and have kept almost daily tabs on the construction, said work appeared to be progressing.

"They have been working continuously," said Andrew Ross, deputy city solicitor. "At this point it seems they are proceeding as quickly as they can."

A visit to the site yesterday found several workers taking the measure of still-unsealed windows. Most of the windows in the five buildings remain open and unsupported. Fencing has been installed, blocking access to the site, and piles of debris and loose bricks have been removed from building interiors and around the site.

The warehouses, at 20 to 30 N. Front St., represent virtually the final remnant of the city's commercial seafaring past.

Contact culture writer Stephan Salisbury at 215-854-5594 or ssalisbury@phillynews.com