PORTLAND, Maine (NEWS CENTER) -- The owner of two tiny homes on a small street in Portland has gotten notification from the city: either move, or apply for a building permit.

The two buildings are on a small lot on Chapel Street; a narrow, one-way cobblestone path just off of Cumberland Avenue.

The owner, Brent Adler, tells our partners at the Portland Press Herald (read more here) that he has tenants ready to move in on November 1st; now he's not sure what will happen.

The units are roughly 400 square feet of living space a piece, and have been hooked up to electrical, water, and sewer lines. The buildings also sit on wheels.

Adler tells the Press Herald that he didn't see anything about zoning rules on RVs so he thought he was in the clear.

City officials issued Adler a notice of violation on Friday for "erecting structures without a permit."

"The tricky part with this one is it's on wheels and in the state building code, which we have to adhere to, you can have tiny houses but they have to be stamped by a manufacturer," said Portland spokesperson Jessica Grondin. "I'm not sure what he's produced is something that would be stamped, so we have to check into that as well."

Grondin says the city isn't against tiny homes, or against working with Adler, they just want him to go through the proper channels so they can deem the buildings safe for occupancy.

"Anything that's not exclusively permitted in the code is then disallowed, so he didn't see anything about RVs so I guess he thought he could go ahead and do it, but again, he had already met with us. He had come in, so we find it a little surprising he didn't want to bring up this new idea with us and see how it would be received."