ADU Rules in Sylmar.
Local ADU regulations, permit fees, setback requirements, and typical timelines for Sylmar (City of Los Angeles). Last updated 2026-05-27.
Sylmar ADU Requirements
Attached ADU: up to 25 ft
Design 4 weeks · Permit 8 weeks · Build 40 weeks
Plain-language summary
In Sylmar (governed by the City of Los Angeles), a detached ADU requires a minimum 4-foot side setback and 4-foot rear setback. The maximum height for a detached ADU is 16 feet, while an attached ADU may be up to 25 feet. The maximum size for a detached ADU is 1,200 sq ft; a Junior ADU (JADU) is limited to 500 sq ft. Replacement parking is not required for most projects. Typical permit fees range from $10,000 to $21,000. A typical project takes approximately ~12 months from design start to move-in, including 4 weeks of design, 8 weeks for permit review, and 40 weeks of construction.
⚠️ ADU rules change frequently. Always verify current requirements with the City of Los Angeles Building & Safety Department before submitting plans. Official source →
What to Watch Out For
- Sylmar is a neighborhood within the City of Los Angeles — all LADBS rules apply.
- VHFHSZ designation applies to most of Sylmar, particularly areas near the Santa Susana Mountains.
- Agricultural (A) zoned lots are common in parts of Sylmar; ADU rules still apply but confirm zone first.
- Hansen Dam and LA River floodplain: some parcels near the dam have flood zone requirements.
How Long Does It Take to Get an ADU Permit in Sylmar?
Site study, floor plans, elevations, structural drawings.
Plan check, corrections, and permit issuance by City of Los Angeles Building & Safety.
Foundation, framing, MEP rough-in, finishes, final inspection.
A licensed engineer on your lot, free.
30 minutes. We walk the property, figure out what's feasible, and answer any questions you have.
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