ADU Regulations

San Marcos ADU Regulations: A Must-Know Guide for Homeowners

March 28, 2024

11 min read

Familiarity with San Marcos’s ADU regulations is crucial for homeowners considering a new ADU project.

Introduction

Understanding the local regulations for Accessory Dwelling Units (ADUs) in San Marcos is essential for homeowners looking to expand their property’s potential. Whether you’re considering building an ADU for rental income, family use, or increasing your property’s value, aligning with San Marcos’s legal standards is crucial. This resource page aims to guide you through the intricate landscape of ADU regulations in San Marcos, ensuring your project is both compliant and optimized for your property’s unique characteristics.

Essential ADU Rules for San Marcos

What you can build

Maximum Sizes
Single-family properties in San Marcos allow one ADU and one JADU, with ADUs up to 850 sq ft for one bedroom and 1000 sq ft for multiple bedrooms. Multifamily properties can add two detached ADUs and convert specific non-livable spaces.
Setbacks
Detached ADUs require a 4-foot setback from side and rear property lines. Converted ADUs don't need extra setbacks if they meet fire and safety standards.
Two-Story
Allowed above garages, subject to height and zoning rules.
Building Separation
Mandated 10-foot separation between ADUs and existing structures.

Permitting timeline

Permitting Timeframe
4-6 months.
Coastal
Not required.

San Marcos ADU Regulations

San Marcos’s ADU regulations are designed to accommodate the growing need for housing while maintaining the character and safety of residential neighborhoods. The city allows for a variety of ADU configurations, including detached, attached, and conversion ADUs, each subject to specific zoning laws, design criteria, and building standards. Unique aspects of San Marcos’s regulations include allowances for two-story ADUs above garages, the requirement for architectural compatibility with the primary residence, and the flexibility in parking arrangements to account for limited urban space.

San Marcos ADU Permitting

The ADU permitting process in San Marcos involves several key steps:

Preparation of Necessary Documents

This includes detailed plans for the ADU design, site surveys, and any required reports (e.g., soils report).

Submission Process

Plans and documents may be submitted digitally or in person, depending on current city guidelines.

Review and Approval Stages

The city reviews the submission for compliance with zoning laws, building codes, and ADU regulations. Adjustments may be required before final approval.

Inspection and Finalization

Upon construction completion, the ADU must pass city inspections before it’s compliant and ready for use.

Our approach at Better Place Remodeling involves sticking to San Marcos’s guidelines and keeping conversations clear with local officials, leading your ADU project to a smooth completion, and turning your dream into reality.

ADU Zoning in San Marcos

In San Marcos, multifamily properties can have two new detached ADUs. Additionally, they can convert existing non-livable spaces, such as garages or storerooms, into ADUs, up to a limit of 25% of the existing unit count of the multifamily building, ensuring at least one conversion ADU is permissible.

The regulations in San Marcos do not specifically mention stacked detached ADUs. However, it is indicated that smaller lots might have the potential to accommodate two new units by stacking them, contingent upon adherence to zoning and height regulations. Property owners considering such configurations should consult with the city planning department for guidance.

San Marcos’ regulations primarily focus on detached, attached, and conversion ADUs, without explicitly addressing the possibility of two ADUs being attached to each other. For guidance on specific projects, contacting the city planning department is recommended.

Yes, in San Marcos, the conversion of non-livable spaces within existing multifamily structures into ADUs is allowed. This includes converting spaces like garages, basements, and storage areas into living units, up to 25% of the existing unit count.

ADUs in San Marcos generally require one off-street parking space. Exemptions apply under certain conditions, such as proximity to public transit, location within a historic district, or attachment to the primary residence, among others.

Parking for ADUs may be provided within setbacks, as tandem parking on existing driveways, or in other suitable locations on the property, provided they meet safety and zoning requirements.

ADU Building Codes in San Marcos

The height restriction for detached ADUs in San Marcos is generally limited to one story, not exceeding 16 feet. However, for detached ADUs located above a garage, there are specific provisions allowing for two-story construction, subject to zoning area height limits.

Information regarding the allowance of roof decks on ADUs in San Marcos is not explicitly provided in the regulations. Property owners interested in adding roof decks to ADUs are advised to consult with the San Marcos city planning department for guidance on current policies and specific project requirements.

In San Marcos, ADUs must comply with specific exterior requirements, including setbacks of five feet from side and rear lot lines for detached ADUs, a height limit of 16 feet (with allowances for two-story ADUs over garages), and architectural compatibility with the primary dwelling. These requirements ensure that ADUs integrate well with the primary residence and maintain the aesthetic coherence of residential neighborhoods.

A four-foot setback from side and rear lot lines is mandated for detached ADUs, with variances for other types of ADUs based on specific conditions, such as conversions from existing structures, where no additional setbacks may be required.

ADUs and existing structures on the same property generally must maintain a minimum distance of ten feet from each other, measured eave to eave, to ensure safety, privacy, and aesthetic considerations are upheld.

Finalizing Your ADU in San Marcos

Navigating the submission and verification steps for ADU development in San Marcos is crucial for a compliant project. This includes understanding the requirement for a building verification survey and potentially a soils report. Parking design and access must consider local zoning laws, offering flexibility for efficient use of limited space. ADUs in San Marcos can be used for long-term rentals, enhancing property value and offering housing solutions. Utilities for ADUs may require separate connections or can be shared with the primary residence, subject to city regulations.

Calculate Your ADU Cost in San Marcos

Using the tool below, you will be able to calculate your investment based on the type and size of the ADU you are interested in building on your property.

Attached ADU

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Estimated Cost

*The costs we are calculating here are an average for time and materials. This calculator is meant to provide an estimate to educate you on the ADU building process, please note that this is not a final quote.

Detached ADU

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Estimated Cost

Garage ADU

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Estimated Cost

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Summary

At Better Place Remodeling, mastering ADU regulations in San Marcos is our specialty, so you don’t have to stress about the details. Our one-stop-shop approach ensures that permits and inspections are completely handled for you. Looking for top-notch ADU builders in San Marcos? We’ve got you covered. We’re here to guide you through the maze of local zoning laws, building codes, and the permitting process, making sure your project is not just compliant but a valuable addition to your home. Trust us for personalized, up-to-date guidance to make your ADU project in San Marcos a seamless and rewarding enhancement to your property.