City of San Marcos
ADU Regulations in San Marcos.
Everything you need to know about building an ADU in the City of San Marcos. Updated for 2025.
ADU Requirements for San Marcos
The City of San Marcos has its own municipal code governing ADU construction. Follows California state ADU law (AB 2221, SB 897, AB 976). Contact us for the latest local requirements.
Maximum Size
1,200 SF (detached) / 1,000 SF (attached)
Height Limits
24 feet (detached, 2-story) / 16 feet (1-story)
Setback Requirements
4 ft side and rear for detached ADUs
Parking Requirements
No additional parking required (as of 2025)
Owner Occupancy
No owner-occupancy requirement
Allowed ADU Types
Detached ADU, Attached ADU, JADU, Garage Conversion
Design Standards
Must comply with applicable building codes
Fees & Impact Charges
Impact fees reduced or waived for ADUs under 750 SF
Building in San Marcos?
Our team knows San Marcos inside and out. We'll handle the entire permitting process so you don't have to.
Free Feasibility Check (858) 788-3839Why CRS for San Marcos:
Frequently Asked Questions
How long does it take to build an ADU in San Marcos? expand_more
The typical timeline for an ADU project in San Marcos is 3–9 months for permitting, followed by 3–6 months of construction. Total project timeline from first meeting to move-in is typically 9–18 months.
How much does an ADU cost in San Marcos? expand_more
ADU costs in San Marcos typically range from $150,000 to $350,000+ depending on size, finishes, and site conditions. CRS Builders provides transparent, fixed-price contracts so you know exactly what you'll pay before construction begins.
Can I rent out my ADU in San Marcos? expand_more
Yes. California law prohibits short-term rentals (under 30 days) for ADUs, but long-term rentals are permitted. There is no owner-occupancy requirement, meaning you can rent out both the main home and the ADU.
Do I need a permit to build an ADU? expand_more
Yes, a building permit is required. CRS Builders handles the entire permitting process — from drafting plans to submitting applications and managing corrections. We take the hassle out of permits so you don't have to.