Honolulu’s housing problem — well within the bounds of a crisis situation for years — could be on the road to a significant improvement, if the latest policy change is managed well by the city administration.

That change is the allowance for accessory dwelling units, or ADUs, what used to be known as “ohana” units except not limited to family rentals. In that sense, the enactment of Bill 20 this week represents a loosening of the rules, but in others there’s been a tightening of the regulations, controls that need to be maintained rigorously.

Recent sewage spills, though some the result of exceptional rainfall, serve as reminders of Honolulu’s history with overburdening its wastewater system, and ADUs can’t be allowed to make such episodes routine. On-site parking stalls should be assured in neighborhoods, many of them with already crowded streets.

And city inspectors, hired with $300,000 in appropriated funds, must persistently monitor for vacation-rental advertisements of these units to keep that abuse from mushrooming.

But if ADUs are to help the city whittle Oahu’s affordable-rentals deficit, the city also will need to whittle the bureaucracy that home builders often face. Many homeowners may feel motivated to create revenue-producing property, but a halting and confusing regulatory process could overcome that incentive.

The city has provided a checklist for applicants to make at least the initial pathway straightforward. The sewer capacity database needs updating and staff will need time before signing off there, but meanwhile the applicant can make the rounds of other agencies to clear or rule out their property for an ADU, before investing time and money pointlessly.

But the lesson learned in other cities where the accessory dwellings have been encouraged is that homeowners need more guidance than that. The requirements spelled out in Bill 20 may seem clear enough, but they don’t address every question.

What apartment model might work best on this lot, and with the current layout of the existing house? How should the lease be written? And how should this project be financed?

Other cities have created manuals and, fortunately, Honolulu is following that example. The Hawaii Appleseed Center for Law and Economic Justice, a nonprofit advocate for affordable housing and other social needs, has been hired to work on a manual, due out early next year. There will be a website and online calculator to help homeowners do the math and figure out if this enterprise will pencil out for them.

The Caldwell administration also plans to press for new regulations incentivizing developers to enlarge the housing inventory that remains in the “affordable” column for a longer period. And there’s the anticipation of dense development around the rail line yielding more rentals for lower-income households, too.

But ADUs, while not the silver bullet, represent a part of the solution. And it’s one that can begin unfolding now, powered by homeowners themselves — as long as the city smooths the pathway for them.