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Granting density bonuses to developers and permitting “accessory dwelling units” on existing residential properties are two ways that state and local governments can encourage housing development for seniors and others, according to a “Housing Development Toolkit” released by the White House.

“Density bonuses … incentivize the addition of affordable housing units by granting projects in which the developer includes a certain number of affordable housing units the ability to construct a greater number of market-rate units than would otherwise be allowed,” the authors said.

The document cites the state of California’s requirement that local governments grant density bonuses, concessions or incentives, if requested, for developments of five or more units that include a minimum amount of affordable housing or senior housing.

Another option, accessory dwelling units — which can be apartments within a single-family home, a cottage attached to the home or a detached structure located on the same property as the home — offers a way to increase available rental housing stock in areas zoned largely for single-family housing and can address the needs of family caregivers responsible for aging parents, the authors said.

“While the number of Americans caring for both an aging parent and a child has increased only marginally, the costs associated with caring for multiple generations has increased significantly as a greater share of parents support their children beyond age 18,” the document stated. “Accessory dwelling units offer one solution to this challenge by facilitating intergenerational living arrangements and allowing more seniors to age in place, something that nearly 90% of older Americans desire for themselves and their families.”

Such units also can permanently increase the available supply of affordable housing, the authors said. Cities such as Portland, OR, and Santa Cruz, CA, have explicitly encouraged the units, according to the authors, whereas other cities, such as San Diego, have called for changes to allow more accessory dwelling units. Earlier this month, they noted, California took action to streamline state regulations to promote the construction of such units.

The publication lists eight other ways that governments can encourage the affordable housing. “This list is not exhaustive — there is a substantial amount of good work being done all around the country — but provides several potential starting points for local efforts to modernize housing planning and development,” the authors said.