SAN RAFAEL -- A prominent Terra Linda hilltop feature for four decades could become home to seniors rather than office workers under a plan to convert the 131,000-square-foot building to housing.

If brought to fruition, One Thorndale would be a novel move for some of the older North Bay commercial space that has been vacant for years and amounting to as much as a quarter of rentable office space in certain submakets. Conversions of offices to residences happened in San Francisco after the dot-com bust emptied buildings. More recently, there have been notable office conversions in the Boston area and northern New Jersey.

[caption id="attachment_82119" align="alignleft" width="350"] The One Thorndale vacant office building on a San Rafael hilltop is being remarketed for 77 senior apartments. (image credit: Cornish & Carey Commercial Newmark Knight Frank)[/caption]

Sausalito-based Berg Holdings Corp. (415-289-4924, bergholdings.com), which owns the vacant One Thorndale Drive building, wants to create 77 age-restricted flats on all three floors, rather than the current configuration of offices on the top floor and part of the second plus parking in the remainder, according to Tennis "JT" Wick, a principal with the firm. The conceptual floorplan calls for a cafe on the first floor, fitness center on the second floor and meeting rooms on the top floor. The existing outside parking lot on the 5.36-acre property would be expanded to move cars out of the building and mostly off the street.

"The building has been vacant for five years," Mr. Wick said. "I think we finally found a use that's going to work there."

Berg Holdings and an unnamed prospective senior-housing developer-operator met with city of San Rafael planning officials several months ago about the possibility of such a conversion.

Berg submitted a preapplication primer on the proposal to Planning Manager Raffi Boloyan on Thursday and plans to turn in a formal application early next year.[poll id="92"]

"When the city of San Rafael adopted the General Plan in 2004, to meet housing needs and mandates one of the things that was encouraged and zoned for was more residential uses in more commercial-use areas," said city Planning Manager Raffi Boloyan. The Association of Bay Area Governments in its 2014--2022 Regional Housing Needs Assessment said San Rafael needed to create 1,003 home dwellings for various income levels in that period.

That would allow multifamily-unit creation by right in an office-zoned area such as One Thorndale's. Depending on what Berg Holdings seeks in its formal application as far as external building modifications and other factors, a basic conversion could proceed to the building permit stage quickly, Mr. Boloyan said.

The three-story building at One Thorndale Drive has been vacant since Take-Two Interactive, formerly Sega Visual Concepts, and then Disney’s ImageMovers Digital animation studio moved to Hamilton Landing in Novato.

There had been interest from large tenants -- particularly, Kaiser Permanente and Marin General Hospital -- for much of the 70,000 to 80,000 square feet of available office space in the building in recent years, but those deals either fizzled or have stalled, according to Brian Eisberg, a longtime agent in the San Rafael office of Cornish & Carey Commercial Newmark Knight Frank. He and David Walwyn of the same brokerage have been marketing the property as office space and more recently as housing.

"It has been challenging to market as office," he said. "It's not as convenient an office location as competitors across the freeway, because they are right off the freeway and this one requires getting off the freeway and going behind the shopping center."

Yet the building's 360-degree views, proximity to shopping and health care, and its large atrium with retractable skylight make it a good choice for conversion to housing, particularly for older residents, according to Mssrs. Wick and Eisberg as well as project architect Tony Battaglia of Santa Rosa-based Archumana. The building overlooks Northgate shopping centers to the east and north, Kaiser Permanente San Rafael Medical Center to the west and Villa Marin, a 224-condominium assisted-living facility directly to the south.Housing conversion quandary

That sizable atrium is important and helps solve what is a common problem with potential conversions of commercial buildings to residential, according to Mr. Battaglia. Because of state building code requirements for daylight and fresh air in residential units, a home created from a commercial building often can only be 40 to 60 feet long from the window line of the building, he noted. A double-loaded corridor design, common in hotels and apartment buildings, allows a building to roughly 110 feet deep while providing windows to dwellings on both sides of the corridor.

Yet a "deep" commercial building that accommodates a sea of cubicles wouldn't accommodate daylit units in the middle without an atrium plus skylight or clerestory. Building design may not structurally or economically accommodate such an addition, according to Mr. Battaglia.

One Thorndale wouldn't be the first commercial property in the North Bay envisioned for housing. The two-building office complex in north San Rafael called Marin Commons had been considered by previous owners for housing conversion, depth limitations of housing units would have been too expensive to accommodate without demolition and new construction. That's what Monahan Pacific did at 33 San Pablo Ave. in San Rafael with an four-story office building, turning it into 82 rental units.Solving the parking problem

At One Thorndale the idea is to create 1,000-square-foot, one-bedroom and 1,300- to 2,000-square-foot two-bedroom units. Seventy-five would be created within existing office or garage space, and two more would be created within the building. A trend in senior housing toward combining smaller units into larger units, as has been done with some condos at Villa Marin, would be an option for One Thorndale, according to Mr. Wick.

Parking has been a constraint at One Thorndale since it was completed in 1971 as the headquarters for tax and business information publisher Commerce Clearing House. To get more housing while avoiding the ventilation issues of vehicles in the same building as dwellings, the plan is to excavate below the existing parking lot south of One Thorndale to accommodate a platform that would create two levels of parking while not disrupting the view from Villa Marin.

The city parking requirement is for 58 spaces, and the current site plan would create 65 spaces. Any other parking could be accommodated on Thorndale Drive, according to Mr. Wick.

There's a plan for an agreement with Villa Marin to accommodate staff parking in the One Thorndale lot, a need that has grown as that facility has added medical and other assistance services over its 27-year history, according to Mr. Wick. And having those medical services next door is a bonus, because medical care isn't planned for One Thorndale, as that would require more space than is available and more scrutiny at City Hall.

However, any residents at One Thorndale may be able to take advantage of the medical staff and facilities next door, according to Thomas Bucci, Esq., chief executive officer of Villa Marin Homeowners Association.

"Should One Thorndale’s future occupants have the need for exceptional inpatient medical services and should we have excess available capacity, we would gladly entertain the possibility of paid use of our 30 bed skilled-nursing center for eligible Medicare posthospital stays," Mr. Bucci wrote in a letter that's part of the senior-housing marketing materials.

Pricing for the planned units at One Thorndale is being explored with potential operators of the community over the next two months, according to Mr. Wick.

He is set to leave Berg Holdings on Oct. 31 for his new role as director of the county of Sonoma Permit & Resource Management Department. Assisting founder Skip Berg in the development role will be Vincent Smith.