Streamline Design Group: ADU Design and Permitting in San Diego
Streamline Design Group specializes in custom ADU design and permitting services across San Diego. Their team focuses on navigating the often complex regulatory landscape surrounding accessory dwelling unit development, working with homeowners and property investors to move projects from initial concept through to permit-ready plans.
As a referenced partner in the State ADU handbook, Streamline Design Group brings a working knowledge of local and state regulations to each project. Their services are aimed at a range of clients, from homeowners looking to generate rental income to those with time-sensitive development needs.
ADU Services Offered
Streamline Design Group provides design and permitting solutions across the full spectrum of accessory dwelling unit types. Their offerings include:
- Detached ADU builder services — creating standalone structures on a property that offer privacy and independence from the main dwelling, suitable for rental units or guest houses.
- Attached ADU design — expanding an existing structure with a connected but independent living space that shares walls with the primary residence while maintaining a separate entrance.
- Junior ADU (JADU) contractor services — converting existing interior space within a home into a self-contained living area of up to 500 square feet, suitable for family members or modest rental use.
- Garage conversion contractor services — repurposing an existing garage into functional living quarters without increasing the property's overall footprint.
- Basement conversion — transforming underutilized basement space into additional living or rental areas within the home's existing structure.
- Multi-family ADU design — helping property owners maximize development potential with multiple dwelling units while navigating complex zoning requirements.
- Site Analysis and ADU Feasibility Studies — evaluating zoning rules, site conditions, utilities, and development potential to determine what can realistically be built before investing in design or construction.
Their draftsmen use CAD software to produce detailed, permit-ready plans. For standard to semi-custom ADU projects, this approach is generally more cost-effective than working with a licensed architect, typically at 40–60 percent lower cost, while still meeting all required building codes.
San Diego ADU Regulations to Be Aware Of
San Diego has established specific rules governing accessory dwelling units. Some key points include:
- Size limits: Detached and attached ADUs can each reach up to 1,200 square feet.
- Setbacks: ADUs up to 16 feet in height may have side and rear setbacks reduced to zero feet. Taller structures or those adjacent to residential properties must maintain at least 4 feet.
- Height: Two-story ADUs are permitted, with height restrictions ranging from 24 to 30 feet depending on the zoning area.
- Building separation: A minimum of 6 feet is required between a detached ADU and the primary dwelling.
- Coastal zones: Properties in coastal zones may require additional permits, including a Coastal Development Permit.
Under updated 2025 regulations, multi-family properties are now permitted to add unlimited ADU units, while single-family lots near public transit may also qualify for multiple ADUs. Only single-family homes retain the option to add a Junior ADU (JADU).
Streamline Design Group's process follows a structured pathway: research and development, design development, consultant coordination, permit management, and contract completion. Their stated goal is to keep projects on schedule and within a predictable cost structure, with design and permitting fees typically representing around 3–4 percent of the total project investment.
For homeowners considering a granny flat, backyard cottage, or casita, Streamline Design Group offers an initial consultation to assess project viability and outline realistic timelines and costs before any commitment is made.