What Are The Common Traits of ADUs?

While their structural forms vary, ADUs share many common traits and face similar design and development challenges. For one thing, the fact that they’re secondary housing units on single-family residentially zoned lots puts ADUs into a unique category. ADUs also have some other distinguishing characteristics that help further define, differentiate, and distinguish them from other housing types.

• ADUs are accessory and adjacent to a primary housing unit.
• ADUs are significantly smaller than the average US house.
• ADUs tend to be one of two units owned by one owner on a single family residential lot.
• ADUs tend to be developed asynchronously from the primary house by homeowner developers.
• A large range of municipal land use and zoning regulations differentiate ADU types and styles, and dramatically affect their allowed uses
• Vast numbers of informal ADUs exist compared to permitted ADUs.

These differentiating characteristics make ADUs a distinct type of housing. Until recently, there has been a lack of common understanding around the language and best practices of ADU development. Source