Making a 509-unit apartment building out of the former Middlesex County Courthouse was imagined Tuesday as a result of changing Cambridge’s zoning code. (Photo: Jimmy Wayne)

The specter of a 22-story, 509-unit apartment building in East Cambridge was only the biggest item casting a shadow over a Planning Board hearing Tuesday about a proposed citywide zoning change.

The board said it would not be acting on the proposal for at least six weeks, or mid-February.

The change would allow developers to make housing out of buildings that had served other purposes — such as the former school on Norris Street imagined only recently to hold 88 bedrooms — in areas not zoned for such multifamily residences. Although it’s the Norris Street property that prompted the proposed zoning change being shepherded by Mayor David Maher, the results would apply throughout the city.

“I would like to point out a couple of the possibly unforeseen consequences,” development watchdog Mark Jaquith told the board during a public comment period. “Take Matignon High School: They could come request 60 apartments in an already very congested area. The Armenian Church at 141 Brattle St.: Ten condos in their back building in an area of expensive, exclusive single-family homes may not go over all that well. And in my own area, we have the high-rise courthouse: Five hundred and nine units.”

Although there was appreciative laughter as Jaquith left the lectern, the notion of the mostly empty Middlesex District Court building becoming apartments for more than 1,000 people was one returned to by board chairman Hugh Russell as he wrapped up the hearing. His summation noted how the board’s schedule coincided with that of the mayor and City Council, which returns to the proposal in an Ordinance Committee hearing Jan. 19, and that changes in it will be sweeping enough that it will have to be refiled anyway.

Points from the public

Russell and others acknowledged a Dec. 28 letter from attorney and former city councillor Kevin P. Crane about the changes, identified as 5.28 for its location in city zoning code, probing their ramifications and making alternate suggestions. The board members also heard lengthy public comment before going around the table for their own reactions.

The gist was that Crane and other commenters had made some good, solid points about the ramifications of the zoning changes.

“This is a case of a building coming forward where the consequences of following the ordinance are different” than what’s desired, and applying the zoning change elsewhere might be equally unwanted, Russell said. “Five hundred units in the courthouse is an amazing thought.”

Member Thomas Anninger acknowledged that 5.28 wasn’t up to dealing with the unforeseen reuse of buildings that could change the nature of a residential block. It was written a decade ago when the city seemed united in simply wanting more housing, he said.

The sale of 22 Cottage Park Ave. is caught up in the zoning problem as well. Neighbors fear the building, owned by the Emerson family and used as manufacturing for medical equipment such as iron lungs, will be sold, torn down and used to build 36 units and an underground garage, hurting the quality of life on a tiny street of single- and two-family homes. They’ve filed a petition to block such a project.

The Emersons’ representative, Ruth Silman of Nixon Peabody, asked that the Cottage Park issue be delayed until the board knew how the amended 5.28 would apply.

Population density

Crane’s letter sums up many of the issues to be grappled with by the Ordinance Committee and board, which will make recommendations back to the full City Council. It addresses whether multifamily dwellings should be allowed at all in certain areas not now zoned for them and how best to calculate the number of allowable units and cars.

Population density is at the heart of the issues, though, and Crane catches a flaw in the amendment’s reasoning on the matter.

“At first glance this amendment would decrease the number of permitted units in Residence B and Residence A [zoning] districts,” Crane wrote, but “a developer of a structure under 5.28 would simply increase the size of the dwelling units by adding additional bedrooms.”

In the Norris Street project, the developer at one point had two units that had eight bedrooms each, for a total of 16 bedrooms and potentially 32 people.

There was one part of the zoning change in which speakers told the board they saw class-based injustice:

The current calculation for number of allowable units is to count up the gross floor area in square feet and divide by 900, but the council petition would have a different divisor in  Residence A and B districts — 2,500 and 1,600, respectively — and leave the 900 figure in place only for so-called Residence C areas.

The result would cram more people into parts of the city with the most density, while lowering the number of people that could move into parts of the city already light on density.

“What we have here is pitting already dense parts of the city against parts that will essentially be upzoned without being told,” Heather Hoffman said. “This is absolutely the wrong way to go about this. We need to stop, sit down and think about what we want this city to be, instead of reacting” to individual developers.