Marin County will appeal a state mandate to plan for thousands of new homes over the next decade, arguing that the allocation does not factor in the county’s unique characteristics that make building difficult.

In a 4-1 vote, the Board of Supervisors directed planners to appeal Marin’s regional housing needs allocation of 3,569 new homes. The appeal also asks the Association of Bay Area Governments, or ABAG, to adjust the allocation to favor more low-income…