A decade after Palo Alto approved a modernist four-story building on Waverley Street over objections of neighbors, a similar project is advancing at the property next door.

The city is now reviewing a proposal at 640 Waverley St. for a four-story building with offices on the ground floor and four residential units on the upper three stories.

The new mixed-use building would occupy a prime downtown site between Hamilton and Forest avenues in the block behind the post office. It would replace two single-family homes that have been around for more than a century, according to a commissioned historical analysis performed by the architecture firm Evans & De Shazo, Inc.

The application submitted in April on behalf of the property owners, James Lin and Clarissa Shen, states that the new mixed-use building would share "material, form and spatial relationships" with the one that was approved in 2014 and completed in 2018 at 636 Waverley St., according to architect Ken Hayes of the firm Hayes Group Architects, who designed both projects.

The new 10,392-square-foot building represents a slight change from Hayes' prior proposal for the site. In 2017, he applied for a three-story mixed-use building with a basement. That project included two floors of commercial space (ground floor and basement) and a residential unit on each of the two upper floors.

The project is located in the "commercial downtown" district and, as such, will not require a zone change to win the city's approval. Last month, Hayes submitted a preliminary application for the new development, which the Architectural Review Board discussed at its June 1 hearing. Hayes is now expected to submit a formal application.

In its first look at the project, the board gave the project a mixed review. While they had no issues with the size of the project or the proposed uses, several board members were put off by the building's concrete facades and urged Hayes to use more eco-friendly materials.

Board members also suggested that Hayes improve accessibility to the building's trash room and consider ways to add more parking to the project (the proposed underground garage would have space for just seven parking spaces).

Board member Osma Thompson also suggested that the new building develop its own identity and not be as closely linked to the adjacent one at 646 Waverley.

"I do think the building shows too much deference to 636," Thompson said. "It almost feels like a sister project to that building, and I think it wants to be different. I think it wants to stand on its own two feet."

Her colleagues agreed and suggested that Hayes consider new materials that would make the exterior less cold and imposing. Chair Peter Baltay criticized the proposed concrete façade at the rear of the property, which includes a staircase tower. The façade would face the Gilman Street farmer's market, Baltay noted, and the large size of the concrete wall "won't fly."

"People see that every day. It's too tall, too black, too much of a piece of concrete," Baltay said.

While Baltay also urged Hayes to add parking spaces to the building, Hayes suggested that providing more spaces on the property would be impossible given the size at the site. Enlarging the garage, he said, would require the construction of a 12- or 16-foot driveway, well wider than the 7-foot driveway that the project is proposing. Given that the project site is just 50 feet in width, a wider driveway would be a "nonstarter."

Hayes also noted that the parking for the building residents would be provided on a voluntary basis. Thanks to Assembly Bill 2097, which became law last year, cities are no longer allowed to impose minimum parking requirements on new developments within a half mile of a major transit station. (In this case, the downtown intermodal transit hub at University Avenue and Alma Street.) That law, Hayes said, allowed the project to advance on a site that the property owner has been eying for redevelopment since 2012.

Prior to AB 2097, the development would have been required to provide 15 spots.

"We elected to provide residential parking -- that means we can get a driveway that's 7 feet narrower and still provides landscaping and give that floor area back to the building," Hayes told the board. "That's what enabled us to move forward in the last six months."