Sunnyvale ADU Permit & Building Guide

At Apex Homes, we’ve designed and built pre-approved ADU homes that provide extra living space, steady rental income, and long-term possibilities, in as little as five months. Sunnyvale, located in the heart of Silicon Valley, offers a strong market for homeowners looking to add value and flexibility to their properties.

ADU Regulations in Sunnyvale

Sunnyvale’s ADU regulations depend on whether your property is a single-family or multi-family lot.

For single-family lots, homeowners can build one detached or attached ADU and one Junior ADU (JADU). Detached ADUs may range from 150 square feet minimum up to 800–1,000 square feet, depending on the number of bedrooms and whether the structure is streamlined. Attached ADUs are generally limited to 850 square feet for one bedroom and 1,000 square feet for two or more bedrooms. JADUs are capped at 500 square feet. Setbacks for detached and attached units are typically four feet from the side and rear property lines, and height is limited to 16 feet for one-story ADUs and 28 feet for two-story additions. Detached ADUs must maintain at least five feet of separation from the main house.

Multi-family lots have additional flexibility. Owners may build up to eight detached ADUs, with attached ADUs allowed for interior conversions up to 25 percent of existing units. Height limits and setbacks vary depending on the location, size, and whether the ADU is newly built or a conversion, but generally range from 16–18 feet for detached structures, and 25 feet or the primary dwelling’s height for additions.

These standards allow homeowners to add functional, high-quality living spaces while preserving neighborhood character.

The Sunnyvale ADU Permitting Process

Getting an ADU permit in Sunnyvale is straightforward. Homeowners typically start with a pre-application meeting at the city’s One-Stop Permit Center to confirm zoning, setbacks, lot eligibility, and parking requirements.

Next, you’ll prepare and submit a complete set of documents, including architectural drawings, structural calculations, a site plan, utility layouts, and Title 24 energy compliance. Applications are submitted online through the E-OneStop portal (or in person) and are generally reviewed within 60 days under California state law. Once approved and fees are paid, the building permit is issued, construction can begin, and inspections are scheduled through the portal.

Apex Homes provides full support throughout this process, including complete permit management, streamlined plan coordination with the city, and a single-point contact to ensure compliance, approvals, and communication with city departments.

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Pre-Approved ADU Plans in Sunnyvale

Sunnyvale offers pre-approved ADU designs to help homeowners move from concept to construction faster. These plans have already been reviewed for compliance with city codes, including zoning, setbacks, height limits, and energy standards. By choosing a pre-approved plan, homeowners benefit from faster permitting, lower design costs, and confidence that the unit meets all city requirements.

Apex Homes offers a selection of Sunnyvale pre-approved ADU layouts and can help you pick the design that best fits your property and goals.

991 3B2B

Essential

Spacious. Smart. Sophisticated.

991 sq.ft. 3 Bed 2 Bath

$350,000

View Product Plan

Why Build an ADU in Sunnyvale?

Sunnyvale is a strong market for ADU investment. With high housing demand in the heart of Silicon Valley, even a modest ADU can generate rental income between $2,000 and $3,500 per month, depending on size and finishes. This creates a steady passive income stream while also increasing property value by 20–30 percent or more.

ADUs also provide flexible living options for multigenerational households. They allow aging parents, extended family or live-in caregivers to enjoy privacy while staying close to family. Aging-in-place designs and flexible layouts can help reduce childcare or eldercare costs while keeping families connected.

Finally, Sunnyvale supports homeowners with streamlined permitting, clear ADU standards, and the option to use pre-approved designs, making the process efficient, cost-effective, and less stressful.