Castaic · ADU permits
ADU permits in Castaic
How to build a ADU in Castaic: permit pathway through LA County Public Works (Building & Safety), drawings required, local watch-outs, and a free address-level wizard for your Castaic lot.
Castaic context
Castaic is unincorporated despite proximity to Santa Clarita city. Permits run through LA County DPW Building & Safety at the Santa Clarita field office via EPIC-LA. Most parcels east of Interstate 5 face VHFHSZ coverage; some hillside review on foothill parcels.
- Permit agency
- LA County Public Works (Building & Safety)
- Median lot size
- 8,200 sqft
- ADU permits issued (2025)
- 48Source: HCD 2025 total (1,278) distributed proportionally across 2024 per-area shares. 2024: 55.
Castaic ADU ordinance
Verified against LA County Public Works (Building & Safety)'s published ordinance on 2026-04-15. State law (CA Government Code §65852.2) overrides any locally-stricter rule.
Max detached ADU size
1,200 sqft (state default)
Max ADU height
16 ft / 18 ft with second-story setbacks
Setbacks
4 ft side / 4 ft rear (state minimum)
Permitting agency
LA County Public Works (Building & Safety)
Fire-hazard construction
Chapter 7A required on VHFHSZ parcels
Local processing time
60 days from complete submittal (state-mandated)
Drawings you'll need to submit
Type your address. See if you can build an ADU, what kind, and exactly how to permit it.
- Site plan (parcel layout + setbacks)
- Proposed floor plan
- Elevations (each side)
- Title 24 CF1R energy compliance
PermitPathLA generates the site plan free from your Castaic address. The other drawings come from your architect or plan firm — we list pre-approved options in the wizard.
Castaic watch-outs for ADU
Overlays that hit a meaningful share of Castaic lots
Very High Fire Hazard Severity Zone (VHFHSZ)~65% of parcels
Most of Castaic. Chapter 7A construction + defensible space at final.
Castaic Dam inundation area~15% of parcels
Some southern Castaic parcels sit in the FEMA-mapped Castaic Dam failure inundation area. Disclosure context.
Local quirks
VHFHSZ on majority of parcels
Roughly 2/3 of Castaic sits in the VHFHSZ. Chapter 7A construction (ember-resistant materials, sealed eaves, etc.) is mandatory.
Run your Castaic address through the wizard
We pull your parcel polygon from county GIS, apply Castaic ordinance + state baseline rules, generate the site plan, and walk you through the LA County Public Works (Building & Safety) submittal. Free, no signup.