Diners in downtown Palo Alto rarely have a chance to dine alfresco while enjoying a bird's-eye view of the streets beneath them.

A tenant of 285 Hamilton Ave., a five-story building that stands across the street from City Hall and that houses the city's Development Services Center, is hoping to change that. That tenant is Houzz, a home-design company that leases space in the prominent building and that hopes to spruce up the design in its own workplace by building a roof-deck patio.

For city planners, the desire for a roof deck is easy to understand. A new report from the Department of Planning and Community Environment notes that rooftop decks "can offer a nice amenity to building occupants and take advantage of outdoor space that may be underutilized."

"Roof decks provide an opportunity for outdoor breakout space, employee break areas, outdoor lunch space, and employee events," the report states. "Roof decks may result in building upgrades that make older buildings more attractive and increase value."

At the same time, city planners warn that in some cases, roof decks may also affect neighboring properties, creating excessive noise, light and glare, compromising privacy and making parking more challenging.

Unfortunately for Houzz, the roof deck in this case would also run afoul of the city's zoning code. The modernist building was constructed in 1971, before Palo Alto adopted its 50-foot height limit, and it exceeds that limit by more than 30 feet. It also houses nearly 50,000 square feet of office space, a significant amount at a time when the city's entire annual allotment for new office space in downtown, California Avenue and El Camino Real is 50,000 square feet.

The city's zoning code doesn't have any specific provisions encouraging or banning roof decks. Rather, they are evaluated for zoning compliance and compatibility on a project-by-project basis, with the understanding that any roof deck would keep the development within allowed design standards.

This process would be trickier for projects like 285 Hamilton Ave., which already fail to conform to code because of their heights and density.

The proposed 2,650-square-foot roof deck, according to staff, would result in a "slightly raised roof surface" and require an installation of guard railings, elevator enclosures, trellises and furniture. As a result, city planners concluded that the "any increase in the nonconforming height or floor area could not be accomplished based on current codes."

One way to get around this challenge is changing the code -- an idea that the council is scheduled to consider on Monday. This could mean creating regulations on what roof decks can be used for and who they can be used by; adopting time restrictions; and requiring developers to set up landscaping and shields to ameliorate lighting and privacy impacts, according to staff.

The council may also consider establishing a review process that would allow the Architectural Review Board to vet a propose design, with public feedback.

A somewhat different option is allowing the building at 285 Hamilton Ave. to build a roof deck as a "test case" for an ordinance that could then be extended to other downtown buildings.

If there is interest on the council for exploring the topic of roof decks, Planning staff recommends exploring the subject of roof decks on a district-wide basis. On commercial corridors such as El Camino Real, which have stretches that abut residential neighborhoods, such additions could be more problematic than in areas like downtown and Stanford Research Park, the staff report states. Roof decks, on nonconforming buildings near single-family neighborhoods are "inappropriate," the report states.

Project applicant James Walgren, a consultant with the lobbying firm Lighthouse Public Affairs, is hoping that the council makes changes that will extend beyond the Houzz project and apply to the broader downtown. The project, he wrote in a letter to Assistant Planning Director Jonathan Lait, "could become a model for other Silicon Valley communities to use for their own downtowns."

"Given the weather climate of the Peninsula area and the culture and innovation of Palo Alto, allowing roof deck patios with land use and traffic impact and parking controls, zoning and building code restrictions and with design review criteria, would seem to be a very positive amendment," Walgren wrote. "And if one or two of these get built during this trial period and the City Council is not happy with the outcome, the ordinance could be rescinded."