It’s taken six weeks since the blaze that killed six young people for the city of Portland to determine that a nearby apartment building owned by the same person has a lot of problems.

Why? Because the city doesn’t require routine inspection of two-unit buildings, like both of these places – 20-24 Noyes St., which burned Nov. 1, and 186-188 Dartmouth St., which was checked out this week. Inspectors go out only in response to complaints. Hence, the fatal fire wasn’t reason enough for the city to immediately check out landlord Gregory Nisbet’s other properties.

Unlike one- and two-unit rental properties, bigger buildings are supposed to be inspected yearly, but statistics show that the city gets around to only 60 percent of these properties. So there are undoubtedly hundreds of other rental units in Portland where similar safety issues are prevalent. The information that’s come to light since the Noyes Street tragedy demonstrates the dire need for the city to change its approach to housing safety and become proactive in identifying its most dangerous rental properties.

Monday’s inspection of 186-188 Dartmouth St., spurred by tenants’ reports last week, confirmed obviously sketchy safety practices. One tenant said Nisbet told him to use the boarded-up doorway to the next apartment as an emergency exit from his third-floor bedroom. The landlord was cited not only for the illegally locked exit doors but also for electrical issues, improperly stored flammable materials and an old, substandard furnace.

In fact, the building – home to seven people – is actually a boarding house, concluded an inspector, and Nisbet should install an alarm system there as well as addressing the other concerns.

Will the residents of Dartmouth Street see any immediate improvements now that their landlord has been cited for fire hazards? Nisbet has about a month to address the violations, but the chance of any substantive change seems unlikely.

Tenants said they’ve been complaining for months to no avail, and the building is in foreclosure, indicating the landlord has little, if any, cash on hand to make fixes. And if no renovations are made, firefighters could declare the building unsafe for occupancy – putting Nisbet’s tenants out on the street at the time of year when Maine sees its worst weather.

Conditions at Dartmouth Street should never have been allowed to get this bad. But the city may be able to keep similar debacles from recurring – if a special panel winds up pressing for the adoption of some of the more promising best practices out there.

One of these – a mandatory landlord registry – is already part of city code, though it hasn’t been enforced. Required registration has worked elsewhere, as long as the fees and penalties for noncompliance are sizable enough to fund the program and give landlords an incentive to take part, a 2013 University of Texas School of Law report has found.

Portland is also looking at enforcing an existing code requiring landlords to hire their own property inspectors, which could work as long as there are protections against lack of accountability on the part of outside experts. Property owners would also have to provide proof that their buildings comply with fire and building codes.

The task force is also expected to call on the city to create a new department to conduct both building and fire inspections and hire cross-trained workers to staff it.

All these measures would allow the city to devote its own resources to unresponsive landlords and buildings with a lot of code violations. Gregory Nisbet may currently be the most high-profile serial violator of Portland’s housing safety ordinances – but he’s not the only one, and the others shouldn’t be allowed to fly under the radar when there are effective ways to identify and penalize them.