To Palo Alto Mayor Greg Scharff, a proposal to a build a roof deck on a prominent downtown building sounds like a "no-brainer."

The addition would create a useful amenity for employees at 285 Hamilton Ave., expand the city's stock of recreation space and turn bland, empty roofs into vibrant gathering spaces, he said Monday night.

"The touchstone should be, 'What makes things better in Palo Alto for residents first and then for employees?'" Scharff said. "I think the roof decks make it much better for everyone."

For Councilwoman Karen Holman, the decision was also easy. At 82 feet in height, the Hamilton Avenue building across the street from City Hall already exceeds the city's height limit by more than 30 feet and is about four times as dense as today's zoning code would allow (this is because it was built before these codes were adopted and is thus considered "nonconforming"). Allowing a 2,500-square-foot gathering area on the roof, from her perspective, would effectively make a project already too big for the area even bigger.

"If something already exceeds what our code says, it's a good policy that we do not increase the nonconformance," Holman said.

Thus, the request for a roof deck by Houzz -- the home-design company that is the main tenant at 285 Hamilton -- became the latest issue to split the council into familiar factions, which those more comfortable with development happily supporting it and those most anxious about growth opposing it.

The council didn't take any votes on the proposal, which is still in a conceptual phase and which has not yet been the subject of a formal application. The pre-screening session was a chance for the council to either nip the project in the bud and avoid unnecessary expenditures or signal its support and suggest ways to improve the project.

The council did both of these things and, in doing so, sent a mixed message to the prospective applicant, building owner Thoits Brothers Inc. But given that the more pro-growth faction enjoys a narrow council majority, the Monday discussion means the application is likely to move ahead.

Scharff, Vice Mayor Liz Kniss and Councilman Adrian Fine were particularly enthusiastic about letting Thoits Brothers and other building owners build roof decks. Fine suggested that these additions will enliven Palo Alto buildings and bring the city's "mojo" back. They will also create more pleasant work spaces and attract better companies, he said.

And when it comes to aesthetics and land use, the choice is between having a roof with air-conditioning and machine units on it or having one with people, Fine said.

"I think a roof with people on it is better, whether it's conforming or not," Fine said.

Not everyone agreed. Several council members raised concerns about possible noise and visual impacts from roof decks near residential areas. Councilman Eric Filseth and Councilwoman Lydia Kou both laughed off Scharff's assertion that a vote against roof decks is effectively a vote against having more park space.

"I don't think this is what most Palo Altans think about when they talk about parks and open space," Filseth said, noting that the city's new parks master plan makes no mention of rooftop spaces. "Given that the building is already 80 feet tall, it's hard to see the argument for expanding it further," he said.

Councilman Cory Wolbach didn't take a firm stance on the Houzz proposal but suggested that the council consider a broader framework for roof deck designs and regulations -- one that considers their potential impacts and mitigates them.

"If we do decide to go down this road, ... we should craft that ordinance to require design and regulations to address noise, privacy, safety and traffic and parking impacts," Wolbach said.

Based on the Monday discussion, such a framework is unlikely to be crafted any time soon. Councilman Tom DuBois specifically asking planning staff not to spend time on this issue, and Filseth said he was surprised that the proposal has already gotten as far as it did. And as city planners move ahead with a long work plan that includes (among many other things) a zoning-code update, a revamp of downtown's parking system, and a new concept area plan for north Ventura, a roof-deck ordinance is unlikely be a department priority any time soon.

Even so, planning staff recommended that if the council supported the roof deck for 285 Hamilton, it should also consider them for other zone-nonconforming buildings. They also acknowledged that different areas may require different regulations.

"Commercial corridors such as El Camino Real, which has stretches of commercial zoning abutting residential districts, may be more problematic than in Downtown or the Research Park," a report from the Department of Planning and Community Environment states. "Roof decks on nonconforming buildings near residential land uses, especially single-family zoned properties, are inappropriate."

Some neighborhood leaders argue that this position doesn't go far enough in protecting residents. Palo Alto Neighborhoods (PAN), an umbrella group with members from different parts of the city, submitted a letter contending that the same logic should apply to commercial areas -- particularly ones where the council is planning to add housing.

If planning staff agrees that roof decks don't belong near single-family neighborhoods, the group asked in the letter, why doesn't the same consideration hold for commercial areas like downtown, which also include residential uses like apartment buildings and condominiums?

The assertion, the letter states, implies "that single family residences are more deserving of protection than multi-family ones."

"The intrusive noise, light and loss of privacy from roof decks near multi-family residences will presumably harm even more people than those near single-family properties," wrote PAN Co-Chairs Sheri Furman and Becky Sanders, Zoning Committee Chair Jeff Levinsky and Zoning Committee member Neilson Buchanan.

But officials from Thoits Brothers and Houzz maintained that the addition will be respectful toward the neighborhood. The roof deck would not be a venue for parties or large meetings but rather a space for an employee to retreat and get a few minutes of fresh air, said Barbara Simmonds, who manages office operations at Houzz.

"I'm looking forward to watching the sun go down over the hills -- and that's it," Simmonds said.

John Shenk, representing Thoits Brothers, said the roof decks are particularly desirable given the city's limited park space.

"Allowing ugly and useless commercial roofs to be converted to attractive and productive things is something that we as a community and you as a council should support -- even encourage," Shenk said.