A rendering of the apartment complex proposed at the Merritt 8 Corporate Park in Stratford.

In the latest case of the sagging office market losing out to new housing, a developer has scrapped an approved-but-never-constructed office plaza plan in Stratford in favor of building 129 apartments.

Mountain Development Corp. of New Jersey wants to use part of its 34-acre Merritt 8 Corporate Park property for a four-story apartment complex.

A little more than 35 years ago, the development vision for that property was a series of mid-rise office buildings near the Trumbull border.

But with the market shifting dramatically since then, Mountain Development is telling Stratford that a big infusion of new housing would serve the town’s needs better.

The plan for apartments adds “needed multi-family residential supply in a commercial corridor already served by existing infrastructure, while preserving the entirety of the site’s significant natural resources,” according to a memo from Russo & Rizio, Mountain Development’s attorney.

“It creates a livable and walkable community with actual connections to abutting commercial properties,” the memo said.

By Stratford’s density rules, a developer theoretically could be allowed to build up to 423 units, according to the attorneys. It is instead offering to put more of the undeveloped section of its land into a conservation easement, and noted that its building would cover just 8% of the land area. With spaces for 330 cars, the overall impervious ground cover would be just under 20%.

Mountain Development is proposing a 2,550-square-foot community building to serve the complex with a fitness center, multipurpose room, restrooms and outdoor swimming pool.

The project would have a mix of studio, one-bedroom and two-bedroom apartments each with their own kitchen and bathroom. Size ranges would be 472 to 597 square feet for studios, 663 to 708 square feet for one-bedroom models and 886 to 1,036 square feet for two-bedroom units. There would be stairways and elevators at the east and west ends of the building, with a mail room and leasing office in the north wing.

Mountain Development emphasized that its project won’t harm nearby properties. The U-shaped building is in the center of the property, buffered by trees from any street frontage.

“A massive open space area, which will be protected by conservation easement, separates the development from residential areas,” according to the company.

“The development will provide growth to the grand list while protecting resources,” the attorneys’ memo said. “Rather than adversely affecting the tax valuation of neighboring properties, the proposed development will likely improve the tax valuation as the residents of the residential building will be a great source of patrons for the abutting commercial properties.”

Stratford’s zoning commission is scheduled to resume its public hearing on the proposal Sept. 23.

Office parks were in vogue when Merritt 8 was constructed in 1989, a time when towns were eager to host hundreds or thousands of white-collar workers while generating taxes from buildings that — unlike factories — didn’t crank out industrial pollution or generate noise complaints.

Developers at the time spoke of up to 440,000 square feet of space along with more than 1,700 parking spaces when the complex was fully built out. But only one structure was actually put up, a 160,000-square-foot office and professional building with a four-story parking garage.

In the years after that building debuted, large-scale employers around Connecticut reduced their appetite for leasing large spaces or even commissioning their own campuses.

Demand eroded enough that by 2016, the 1.3 million-square-foot Aetna complex in Middletown was demolished. The Hartford tore down its 600,000 square feet of space in Simsbury around the same time.

Nationally, the pandemic delivered a hit that the office market hasn’t recovered from.

Cushman and Wakefield reported this summer that Fairfield County’s office vacancy rate is dropping, a good sign for owners. Still, 16% of the office space in Stratford and Shelton remains empty, while new office construction is off historical averages by about 70%.