Ten Seventy Architecture: ADU Design Services in San Diego
Ten Seventy Architecture is a San Diego-based architectural firm that works on a range of residential projects, including Accessory Dwelling Units (ADUs). The firm is led by Sean Canning and his team, who guide clients through the design and permitting process for ADU projects across the San Diego area. Their work spans detached ADU builds, garage conversions, and other accessory dwelling unit types, with a focus on functional and creative design solutions.
As an experienced ADU contractor and design firm, Ten Seventy Architecture handles projects from initial concept through to construction documentation. They are known for listening to client needs and translating those into workable architectural plans. Their process is structured to move clients from broad ideas toward detailed specifications in a clear, step-by-step manner.
Understanding ADUs and the Design Process
An Accessory Dwelling Unit (ADU) is a legal structure that serves as an accessory to a primary dwelling. ADUs have become increasingly common in California as a strategy to address the state's housing shortage. They can range in size from 150 to 1,200 square feet, depending on local regulations. Some municipalities allow multiple ADUs on a single lot, particularly in multi-family or transit priority zones.
A Junior Accessory Dwelling Unit (JADU) is a more restricted type of accessory structure, generally limited to 500 square feet and required to be attached to an existing structure. Not every lot qualifies for a JADU, and specific local rules apply.
The timeline for an ADU project in San Diego varies considerably. The early stages involve requesting record drawings, documenting existing site conditions, researching applicable codes, and consulting with municipal staff. Design work for smaller ADU projects can take as little as two months, while more complex builds take longer. Once design is complete, architectural construction drawings are produced and engineering work begins — a phase that typically takes one to two months. Permitting timelines are highly variable; while California requires ADU permits to be processed within 60 days, real-world timelines can range from three months to well over a year depending on the permit type required. Construction itself adds further time, with even smaller projects taking at least six months to complete.
ADU Project Costs in San Diego
ADU projects involve both soft costs and hard costs. Soft costs include architectural design, structural engineering, energy consulting, and permitting fees. Ten Seventy Architecture has set a minimum architectural design fee of $20,000, reflecting the complexity of ADU permit submissions in California. Most projects also require a structural engineer and an energy consultant to produce a Title-24 Report.
Permitting costs vary depending on the municipality and the type of permit required. A Coastal Development Permit or Site Development Permit will typically cost more than a standard permit. Municipal fees for ADUs are generally lower than those for a primary dwelling of equivalent size.
Hard costs — covering materials and labor — have increased significantly since the start of the global pandemic. Current minimum construction costs in Southern California are approximately $250 to $300 per square foot. Custom finishes and features will push costs higher. It is also worth noting that smaller ADUs may carry a higher cost per square foot than larger ones.
Ten Seventy Architecture works on a variety of accessory dwelling unit types, including detached ADU builds, in-law suites, backyard cottages, and JADU projects. Their team brings both design experience and local code knowledge to each project, which can be particularly useful given how much ADU regulations vary between San Diego municipalities.
