Accessory Dwelling Units — commonly called ADUs — have become one of the most discussed property topics throughout California and especially here in San Luis Obispo County.
The reasons homeowners consider them are varied and personal. Some want to create rental income to offset their mortgage payment. Others want space for aging parents, adult children, or extended family. Some need a dedicated guest space or a home office that is truly separate from the main house. Others are thinking about long-term property utility, resale value, or future flexibility.
What all of these projects have in common is this: they are real construction projects with real budgets, real timelines, and real financing requirements.
And the single most important first step — before you call a contractor, before you hire an architect, before you pay for a site plan — is to understand what you can finance and how.
Your Local ADU Financing Expert
Justin Stearns, Mortgage Broker — Assist Home Loans
Justin works with San Luis Obispo County homeowners who are planning ADU projects and need to understand their equity position, compare financing options, and build a realistic project budget — before committing to design or construction.
Schedule a ConsultationCommon Homeowner Questions
5 Important ADU Questions for San Luis Obispo County Homeowners
Click each question to expand the answer.
Financing an ADU is not one-size-fits-all. The right option depends on your current mortgage rate, available home equity, income, credit profile, project budget, and whether you want to refinance your existing first mortgage or keep it in place.
Here are the main ADU financing options to compare with Justin Stearns:
No single option is right for every homeowner. Schedule a consultation with Justin Stearns to compare these side by side for your specific situation.
Talk to Justin Stearns Before You Spend a Dollar on Plans
Free consultation. No obligation. Serving all of San Luis Obispo County.
The Most Important First Step
Why Financing Comes Before Design
One of the most common and costly mistakes homeowners make when planning an ADU is investing money in plans, architectural drawings, or contractor bids before confirming what they can actually finance.
A detailed set of architectural plans might cost several thousand dollars. Permit fees can add up quickly. Contractor bids require time, site visits, and detailed scope documents. If you spend that money and then discover the financing doesn't work the way you expected — or that the budget is too tight to proceed — you've wasted time and money that could have been avoided.
Design a project that matches the numbers — not the other way around.
Before you engage any other professional, review the following with Justin Stearns:
Available home equity
Estimated current property value
Current mortgage balance
Current mortgage interest rate
Monthly payment comfort zone
Renovation loan eligibility
Fixed-rate second mortgage options
Cash-out refinance tradeoffs
Estimated ADU project budget range
The Full Process
Step-by-Step: Adding an ADU in San Luis Obispo County
A general overview of the process. Every project is different. Consult with qualified professionals for your specific situation.
Schedule an ADU Financing Consultation
Before anything else, schedule a consultation with Justin Stearns at Assist Home Loans to review your equity, mortgage, and financing options. This step is free and sets the foundation for everything that follows.
Schedule with Justin Stearns → calendly.com/justinstearnsConfirm Your Property Jurisdiction
Determine whether your property is in unincorporated San Luis Obispo County or within city limits. Rules vary significantly by jurisdiction.
Review Site Feasibility
Evaluate zoning, setbacks, lot coverage, utilities, parking, fire access, septic or sewer, coastal-zone requirements, and any other property-specific constraints.
Choose Your ADU Type
Decide between a detached ADU, attached ADU, garage conversion, interior conversion, Junior ADU (JADU), prefab unit, or pre-designed plan — based on budget, lot layout, privacy needs, and rental goals.
Build a Preliminary Budget
Develop a realistic budget that includes plans, engineering, permits, site work, construction, utility upgrades, contingency reserves, and financing costs.
Assemble Your Professional Team
Engage the right professionals for your project scope and complexity.
Mortgage Broker / Loan Advisor
Start here first
General Contractor
Manages construction
Architect, Designer, or Draftsperson
Plans and drawings
Structural Engineer
As required
Civil Engineer
If needed
Surveyor
If needed
Energy / Title 24 Consultant
Required
Septic Consultant
If applicable
Planning Consultant
Complex sites
Insurance Advisor
Liability & builder's risk
CPA or Tax Advisor
Rental income planning
Property Manager
If rental income is the goal
Submit Plans and Permit Application
Work with your designer or architect to prepare construction documents and submit to the appropriate city or county planning and building department.
Finalize Financing and Close the Loan
Complete your mortgage application, satisfy underwriting conditions, and close your loan before or in coordination with the construction start.
Build and Complete Inspections
Construction proceeds through required inspections at each phase. Final inspection and certificate of occupancy are required before the ADU can be occupied.
Plan for Occupancy and Long-Term Use
Consider rental strategy, insurance updates, property tax implications, property management, and long-term property planning.
Local Jurisdiction Notes
ADU Planning Notes by Area
A high-level reference only. Always verify current requirements directly with the applicable planning department.
Unincorporated SLO County
Governed by San Luis Obispo County Planning & Building. Pre-reviewed ADU plan resources may be available through the county. Site-specific review is still typically required. Verify current rules and fees with San Luis Obispo County.
City of San Luis Obispo
The City of SLO has its own ADU and JADU development standards, including setback, height, and coverage requirements. Review current standards with the City of San Luis Obispo Community Development Department.
Paso Robles
The City of Paso Robles has its own zoning and ADU requirements. Verify current ADU standards, fees, and permit processes with the City of Paso Robles Community Development Department.
Atascadero
Atascadero has city-specific ADU zoning rules and requirements. Confirm site eligibility, setbacks, and permit requirements with the City of Atascadero Community Development Department.
Arroyo Grande
Arroyo Grande has its own ADU ordinance and development standards. Verify current zoning, fees, and requirements with the City of Arroyo Grande Community Development Department.
Grover Beach
Grover Beach has city-specific ADU rules. Some areas are near the coast, which may trigger additional coastal-zone review. Confirm requirements with the City of Grover Beach.
Pismo Beach
Pismo Beach is a coastal city. Depending on the property location, coastal-zone review may apply. Verify ADU eligibility, coastal requirements, and permit process with the City of Pismo Beach.
Morro Bay
Morro Bay is a coastal community. Coastal-zone requirements may apply to some properties. Verify ADU standards and permit requirements with the City of Morro Bay Community Development.
Talk to Justin Stearns Before You Spend a Dollar on Plans
Free consultation. No obligation. Serving all of San Luis Obispo County.
Disclaimer: Loan programs, rates, terms, eligibility, and guidelines are subject to change and borrower qualification. This is not a commitment to lend. ADU rules vary by jurisdiction and property. Homeowners should verify current planning and building requirements with the applicable city or county department.