From the kitchen window of her Kaimuki home, Christine Otto Zaa can see the roof of a “monster” house so big she calls it “Noah’s Ark.”

“That’s a 9,000-square-foot lot, 16 bedrooms, 12 bathrooms, two half-baths,” she said. She found ads on Craigslist for several units in the house: $2,200 a month for a two-bedroom, one-bathroom apartment, including stove and refrigerator. The listings also say “coin-operated washer/dryer on site.”

“It’s a business in a residential neighborhood. It’s an apartment building,” she said.

Otto Zaa has compiled a spreadsheet of suspected monster houses that are taking over her neighborhood, a roughly 1-mile radius near Kapiolani Community College. She and her husband have gone through the narrow Kaimuki and Kapahulu streets to take note of new construction in the area, and then looked up data on the lot size, building square footage, number of bedrooms and bathrooms. She then calculated the floor area ratio (FAR) — that’s the ratio of usable floor area to the size of the lot — and came up with a list of nearly 40 properties that have been or are being built to max out the lot and create “apartment houses” in the residential area. One morning, she drove me around to show me the houses on her list.

“The media has focused on the three-story houses, but it’s two-story houses that are taking over the neighborhoods,” she said.

She pointed out some telltale signs: huge houses with no garages. Two houses squished together on the same lot with just a masonry firewall in between. In some cases, the old house remains in the front while a hulking new concrete house is connected in the back. One house we passed has six exterior doors on one side, each a separate entrance into an apartment unit.

One of the challenges facing the city has been trying to define a monster house. The most egregious ones are obvious, but there are many variables. Some developers subdivide a lot to get more building square footage on the property. Some list two attached homes under different owners.

Otto Zaa first started noticing old houses in Kaimuki being sold, leveled and replaced by big houses in the early 2000s. Then, a house on her street went on the market and her friend’s family tried to buy it. They were outbid by an offer well above the asking price by an investor from China. That’s when Otto Zaa started paying close attention and noticing that Hawaii families were being outbid on many houses that came on the market.

“These investors don’t care if they bid over the asking price. They’ll build a monster house for cheap and make a ton of money on the rent,” she said.

She contacted residents in nearby neighborhoods like Palolo and Kapahulu who were quoted in newspaper stories about their concerns over monster houses, and they formed a group called Hi Good Neighbor. They’ve been collecting data, going to Honolulu City Council meetings, trying to figure out how best to keep their neighborhoods from being overrun and overburdened by these apartment buildings disguised as houses.

“Any kind of legislation needs to be data-based,” she said. “It can’t just be based on anecdotal evidence.”

She’s worried about the proposed moratorium that will come up for a vote by the City Council on Tuesday. The measure is meant to be a temporary step before land-use ordinances can be changed to address the growing problem.

She doesn’t agree with the proposal to tier the FAR based on lot size. She thinks a FAR of 0.75, which would apply to lots of up to 3,500 square feet, is too much. Instead, she thinks setting the FAR at 0.60 and limiting the number of bathrooms would stop the apartment-style monsters but allow for true multigenerational living arrangements.

“The argument that these monster houses create affordable rentals is ridiculous; $2,200 for a two-bedroom is not affordable,” she said.

Otto Zaa grew up in a multigenerational home in Kapahulu. “The house was 1,000 square feet, three bedrooms, one bath, with my grandparents, my uncle, my mom and three kids,” she said. “That’s how low- to mid-income multigenerational families live. You don’t need 5,000 square feet.”

Reach Lee Cataluna at 529-4315 or lcataluna@staradvertiser.com.