Montgomery homeowners who want to add a small apartment for an aging parent, a caretaker or a renter to help cover the mortgage, can do so more easily under streamlined regulations passed Tuesday by the County Council.

Under the old rules, securing approval for an “accessory apartment” required an elaborate process of official reviews and hearings that took a minimum of five to six months, county officials said.

The new measure allows for licensing in about 90 to 110 days.

The plan has drawn opposition from residents concerned that the apartments, which require their own kitchen, bathroom and entrance, would create issues with parking, trash or overcrowding of neighborhood schools. But county officials said they believe most apartment occupants will be single adults who either can’t afford the region’s expensive housing market or who don’t want to maintain a home.

The measure limits the number of apartments to one in every five houses on a block. It also restricts their size to 1,200 square feet. Neighbors still have a chance, as they did under the old rules, to contest any proposed apartment before a hearing officer.