Builders of so-called illegal monster homes and other city building code violators now face stiffer penalties under a bill signed into law by Mayor Kirk Caldwell on Thursday.

The new law dramatically increases fines, makes fines non-negotiable, and may force a property owner to tear down an entire building — or at least the portion found to be in violation.

The City Council passed Bill 53 on Sept. 12, sending the measure to the mayor’s desk. Caldwell thanked Council member Kymberly Pine, chairwoman of the Council’s Zoning Committee, for introducing it.

“The issue of so-called monster homes has frustrated the residents of many Oahu neighborhoods, but with Bill 53 now becoming law, anyone who continues to build without a proper permit, or does not follow the law concerning owner-builders, will be severely fined,” Caldwell said in a statement.

Under the new law, those who build without a permit and are ordered to suspend work would pay an initial civil fine that is 10 times the amount of a building permit fee or $10,000, whichever is greater, for each day the violation persists. Previously, a party slapped with a Notice of Order for violating any part of the code paid a flat $2,000 fine, plus $2,000 a day for each additional day of the violation.

The bill was driven, in part, by a growing perception that the city’s Department of Planning and Permitting is incapable of cracking down on violators of building and zoning laws, particular amid the outcry over the proliferation of large-scale or “monster houses.” Often appearing in older urban Honolulu neighborhoods, the large houses are viewed by many as out of character.

The new law would target homes like the one on Date Street that the Honolulu Star-Advertiser reported on earlier this year after it went up despite having no approved building permit and the city issuing a stop-work order. As of Wednesday, DPP reported that the building permit for the property was still pending, and that the owners had accumulated $184,000 in daily fines for working without a permit. They also had accrued $20,000 in daily fines for an illegally constructed wall.

The project’s contractor said he proceeded without a building permit because it would have been economically unfeasible to delay construction until he could get one.

The Council earlier this year adopted a moratorium on large-scale homes to give DPP time to come up with a more permanent law that would discourage them. The draft DPP plan is expected to be heard by the city Planning Commission next month.