The city has been toughening its approach to regulation of single-family residences that have ballooned in size to accommodate much more than a single family: A moratorium was put in place in March while the city worked on more specific rulemaking.

That is a welcome impulse, but it’s become clear to the Honolulu City Council that new, even tougher action is required to keep the scofflaws deterred.

Today the Council takes up legislation with this aim, two bills that would increase fines on so-called “monster houses,” and to require the demolition of construction that doesn’t meet regulations.

While this seems an extreme course of action, it’s plainly the only penalty that the most aggressive violators will understand.

That said, there’s room for debate on some other proposed provisions, such as making the existing moratorium retroactive to permits issued after Jan. 1, 2016. Whether or not that’s legal, it doesn’t seem fair.

There’s been a community uproar over these houses, some of which have the misplaced appearance of an apartment building within a lower-density residential zone.

But the problem goes beyond grievances about interrupted views or mere complaints about how it looks. The fact is that these accommodations can significantly increase the population density in a community, pushing it past the capacity that the area sewers and water mains can handle.

The structures have risen in aging neighborhoods such as Kamehameha Heights and Palolo, but the case of a duplex on Date Street has become a particular thorn in the side for city elected officials. In addition to constructing much of the project without a building permit, the developers carried on with construction even despite a stop-work order.

Something has to happen to put the brakes on such projects, and to demonstrate that the city has the will to enforce its laws.

Two measures under review today by the Zoning and Planning Committee:

>> Bill 50 raises penalties on contractors or homeowners who violate the interim moratorium on large-scale houses, on the books since March, and it makes that moratorium retroactive.

The moratorium ordinance had set requirements and limits on elements such as required parking stalls, number of laundry rooms and wet bars, defining the required setbacks for houses of various sizes.

In addition to civil fines, any order issued against those homes or partial structures would require demolition, assuming that they still lack a permit, don’t meet the legal requirements and work has continued despite the issuance of a notice of violation.

>> Bill 53 increases the amount of fines, and would apply to a structure, or a portion of one, that “is erected, constructed, enlarged, altered, improved, or converted without the necessary permit” and where work has continued despite an order to suspend work. In such a case, instead of paying a fine up to $2,000, the penalty would amount to $10,000 or 10 times the building permit fee amount, whichever is greater. Further, the violator would be barred from negotiating with the Department of Planning and Permitting to lower the penalty, as often happens.

Honolulu is a dense city with aging roads, water and sewer facilities, one where the density is only going to increase, especially in its urban core. The construction of rail and transit-oriented development housing are primary drivers of this trend.

It won’t do to further burden infrastructure by enforcement agencies turning a blind eye toward construction that’s not aligned with Honolulu’s land-use planning.

If builders do not see the threat of penalty as credible, there will be no way to curb bad behavior. The prospect of demolition would be such a curb.

And there must be boundaries, lest Oahu neighborhoods lose the character residents prefer.