New Detached Accessory Dwelling Units (ADUs) are becoming a popular housing trend in California; but of course, it's not as easy as simply slapping up a structure. Structural engineering plays an important role in these structures and must be considered when designing them. The structural engineer needs to evaluate the conditions of the soils and the site before they can effectively design the foundations that will support the building and meet existing codes. Construction plans take into account both safety factors and the materials needed for durability and economics. All of this planning is vitally important, helping to ensure California's new ADUs are safe, secure, and cost-effective for their owners.