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If you own land or are planning to build in the hillside areas of Los Angeles — the Santa Monica Mountains, the Hollywood Hills, Bel Air, Studio City, Encino, Malibu, Palos Verdes, or any of dozens of similar neighborhoods — you are subject to a set of building regulations that go far beyond the standard Los Angeles Municipal Code. The Hillside Ordinance is not a single document. It is a layered system of grading rules, height limits, slope density calculations, foundation requirements, fire zone overlays, and environmental protections that collectively govern nearly every decision on a hillside project. This guide explains the complete framework — the code sections that matter, what they require, and how they affect your project in practice. DWD Builders has navigated this regulatory environment on projects across Encino, Malibu, Bel Air, Palos Verdes, and the Santa Monica Mountains foothills.
The term “Hillside Ordinance” in Los Angeles refers primarily to the regulations embedded in the Los Angeles Municipal Code (LAMC) Article 7 of Chapter IX, commonly known as the Los Angeles Building Code. The key sections governing hillside construction are:
Beyond the LAMC, hillside projects in Los Angeles are also governed by the California Building Code (CBC), the Los Angeles Fire Code, the Grading Manual published by LADBS, applicable portions of the Alquist-Priolo Earthquake Fault Zone Act, and in coastal hillside communities, the California Coastal Act as administered by the California Coastal Commission. Understanding which bodies of law apply to your specific site is the first step in any project.
Under LAMC Section 91.7002 and the associated zoning maps, a “Hillside Area” is defined as any area within the City of Los Angeles that has been designated as such on the official Hillside Area maps maintained by LADBS. The designation is tied to topographic features — primarily slope percentage and elevation — but the boundaries are regulatory, not purely geographic.
In practice, the Hillside Area designation covers the following major zones (among others):
The only reliable way to confirm whether your specific parcel is within a designated Hillside Area is to check with LADBS directly or review the official LADBS Zoning Information and Map Access System (ZIMAS). Many properties that owners assume are “flat enough” to avoid Hillside Area status are in fact within the designated boundary. This matters because Hillside Area status triggers the full suite of restrictions below.
The grading regulations under LAMC Section 91.7006 and the LADBS Grading Manual govern every aspect of earth movement on a hillside lot — from a minor landscaping regrade to a full-scale pad cut for a new home. Key requirements include:
Any grading on a hillside lot that involves more than 100 cubic yards of earth movement, or any grading that creates a cut or fill slope exceeding 5 feet in height, requires a Grading Permit from LADBS. This is separate from and in addition to any building permit. The grading permit application must be accompanied by a grading plan prepared by a licensed civil engineer, a soils report prepared by a licensed geotechnical engineer, and an erosion control plan.
Under LAMC 91.7006, cut slopes may not exceed 1:1 (45 degrees) and fill slopes may not exceed 2:1 (horizontal:vertical) without specific geotechnical justification. Slopes steeper than these limits require engineered slope stability analysis and are subject to LADBS discretionary review. Most residential hillside projects use 2:1 fill slopes as the standard.
While there is no absolute maximum volume of grading permitted, LADBS applies increasing scrutiny to projects involving large earth movements. Projects in Very High Fire Hazard Severity Zones (VHFHSZ) face additional review for vegetation removal associated with grading. The Hillside Area designation also limits the disturbed area of a lot relative to total lot size.
All graded pads must drain away from structures at a minimum grade of 2% for the first 10 feet. Hillside lots must include engineered drainage that directs runoff to public streets or approved drainage facilities — not onto adjacent properties. Swales, drain pipes, and energy dissipators are typically required. These drainage systems must be shown on the grading plan and approved by LADBS.
All fill material must be compacted to a minimum of 90% relative compaction per ASTM D1557, verified by a licensed geotechnical engineer with field density tests at specified intervals. The soils engineer of record must certify compaction compliance before LADBS will approve the grading for building foundation work.
Effective erosion control measures must be in place before October 15 each year (the start of the LADBS-designated rainy season). This includes temporary and permanent measures: silt fencing, straw wattles, hydroseeding, and where appropriate, geogrid-reinforced slope protection. Failure to implement erosion control can result in stop-work orders.
The Hillside Area height regulations under LAMC Section 12.21 A.17 are among the most misunderstood aspects of hillside building in Los Angeles. The height limit in most Hillside Area zones is 45 feet — but the measurement method is fundamentally different from flat-lot height measurement and consistently surprises owners and designers who are not familiar with hillside-specific rules.
On a standard flat lot, building height is measured from the average grade at the perimeter of the building to the highest point of the roof. On a hillside lot, LADBS uses the average natural grade method, which calculates the average elevation of the lot’s natural (pre-construction) ground surface across the footprint of the proposed structure. The height is then measured from that average to the highest point of the building.
In practice, this means that a three-story home on a steeply sloping hillside lot can appear to have four or five stories of visible facade on the downslope side, while still technically complying with the 45-foot height limit as measured from average natural grade. Conversely, on lots where the natural grade rises sharply above the building pad, the average natural grade method can actually be more restrictive than a simple perimeter measurement.
Beyond the absolute height limit, LADBS also enforces view corridor protections in many hillside neighborhoods through specific overlay plans. The Mulholland Scenic Parkway Specific Plan, for example, imposes additional height and massing controls on properties visible from or adjacent to Mulholland Drive.
One of the least understood but most consequential provisions of the Hillside Ordinance is the Slope Density Formula under LAMC Section 12.21 C.10. This formula reduces the maximum allowable floor area ratio (FAR) of a structure as the average slope of the lot increases.
The formula is straightforward in concept but requires precise topographic survey data to apply correctly. The average slope of the lot is calculated, and a percentage reduction is applied to the otherwise allowable floor area. For lots with average slopes between 15% and 30%, the allowable floor area is reduced incrementally. Lots with slopes exceeding 30% may face reductions of 50% or more relative to an equivalent flat-lot FAR.
| Average Lot Slope | Approximate FAR Reduction | Practical Impact on 10,000 SF Lot |
|---|---|---|
| Under 15% | None | Full FAR applies — typically 0.45–0.50 for R1 |
| 15%–20% | ~10–15% reduction | From 4,500 SF to ~3,800–4,050 SF max |
| 20%–25% | ~20–30% reduction | From 4,500 SF to ~3,150–3,600 SF max |
| 25%–30% | ~30–45% reduction | From 4,500 SF to ~2,475–3,150 SF max |
| Over 30% | 45–60%+ reduction | From 4,500 SF to under 2,000 SF max |
These figures are illustrative. Actual calculations require a licensed surveyor’s topographic data and application of the full LAMC 12.21 C.10 formula by a licensed architect or engineer.
The slope density formula is one of the primary reasons why hillside lots in Los Angeles — even large ones — often cannot accommodate the home size an owner envisions. We strongly recommend having a licensed architect apply the full slope density calculation before purchasing a hillside lot or finalizing a design program.
Hillside Area setbacks differ from standard residential setbacks in two important ways. First, the standard front, rear, and side yard setbacks of the applicable base zone (typically R1) still apply. Second, additional setbacks specific to hillside conditions are layered on top.
The majority of hillside land in Los Angeles — including virtually all of the Santa Monica Mountains, the Hollywood Hills, the Encino and Sherman Oaks hills, and the Palos Verdes Peninsula — is designated as a Very High Fire Hazard Severity Zone (VHFHSZ) under California Government Code Section 51179. This designation triggers construction requirements that are separate from, and in addition to, the standard Hillside Ordinance.
The primary construction standard for VHFHSZ lots is California Building Code Chapter 7A — Wildland-Urban Interface (WUI) construction. Chapter 7A applies to any new structure on a lot within a designated VHFHSZ and to additions exceeding 50% of the existing structure’s value. Key Chapter 7A requirements include:
Class A fire-rated roofing material (concrete tile, metal, or Class A-rated asphalt shingle) on all new structures.
All attic vents, foundation vents, and underfloor vents must be listed as ember-resistant, typically with 1/16-inch mesh screens.
Non-combustible or fire-resistant siding on exterior walls within 0–30 feet of the property line in the fire zone.
All exterior decks and their supporting members must be constructed of ignition-resistant or non-combustible material within 0–30 feet.
Tempered or multi-pane glass on all windows and skylights. Single-pane glass is not compliant in VHFHSZ.
Under LAMC 57.118.5, all new residential construction in a Very High Fire Hazard Severity Zone requires an automatic fire sprinkler system throughout the structure.
Post-2025 FHSZ map updates expanded the VHFHSZ boundaries in several Los Angeles neighborhoods. If you have not recently confirmed your property’s fire hazard designation, it should be verified before proceeding with design — the boundary updates following the 2025 wildfires are significant and affect properties that were previously outside the high hazard zone.
Hillside building permit applications in Los Angeles go through a more intensive review process than standard residential permits. Understanding this process is critical to building a realistic project schedule.
Before submitting any permit application, confirm the following: Hillside Area designation (ZIMAS), VHFHSZ designation (CAL FIRE/LADBS fire hazard maps), Alquist-Priolo Fault Zone status, Coastal Zone status (if applicable), any active Specific Plans affecting the property (Mulholland, Baseline Hillside Ordinance, etc.), and any active BOE-designated landslide or grading moratorium areas.
Commission a licensed geotechnical engineer to conduct a site investigation and produce a soils report meeting LADBS requirements. This report must be submitted with both the grading permit application and the building permit application. The soils report drives foundation design, slope stability conclusions, and drainage recommendations — it is the foundation of everything that follows.
A licensed civil engineer prepares a grading plan meeting LAMC 91.7006 and LADBS Grading Manual requirements. The grading plan is submitted to LADBS for plan check, typically by the District Office serving the project location. Hillside grading plan checks take 4–12 weeks as of mid-2026.
Building plans are submitted simultaneously or after grading approval. Hillside projects require structural calculations that integrate with the foundation and geotechnical recommendations. Plan check for hillside residential projects currently takes 6–14 months through standard LADBS over-the-counter and regular plan check processes. Expedited plan check (PCO) is available for a premium and can reduce this to 3–6 months.
LAFD reviews plans for fire access (minimum 20-foot driveway width), turnaround requirements, fire hydrant proximity (within 300 feet), and fire sprinkler system design. Fire Department review typically runs concurrent with LADBS structural plan check but may require separate submittal.
For lots in or near drainage channels, hillside moratorium areas, or properties adjacent to public streets requiring dedications or improvements, the Bureau of Engineering will have review authority over portions of the project.
Within the broader Hillside Area, the Los Angeles Bureau of Engineering has designated certain sub-areas as Special Grading Areas due to historical slope instability, active landslide movement, or other geologic hazards. The most significant of these is the Hillside Grading Moratorium Area, established following catastrophic hillside failures in the 1950s and 1960s.
Properties within a Special Grading Area face the most stringent grading review in the city. In some areas, any grading whatsoever — including minor grading for landscaping — requires a Geologic Hazard Report in addition to the standard soils report, and may require review by the City Geologist or a BOE-approved independent geotechnical engineer of record.
These areas are concentrated in and around known landslide zones including Pacific Palisades, portions of Bel Air, the Cahuenga Pass, and specific hillside areas of Hollywood. Confirming whether your property falls within a Special Grading Area is essential before purchasing or designing.
DWD Builders has completed hillside residential and mixed-use projects across Los Angeles, including:
The hillside regulatory environment is genuinely complex, and the consequences of misunderstanding it are severe: projects designed to a program that violates the slope density formula must be redesigned; structures permitted without proper grading analysis face stop-work orders; buildings in VHFHSZ zones without Chapter 7A compliance fail inspection. Every one of these scenarios adds months to a project and significant cost.
Our recommendation is consistent: engage a licensed hillside-experienced architect and geotechnical engineer before you spend a dollar on design. The pre-design feasibility work — confirming Hillside Area status, fire zone designation, slope density capacity, and foundation requirements — typically costs $15,000–$40,000 and saves multiples of that amount in redesigns and surprises during construction.
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DWD Builders has navigated the LADBS hillside plan check process on projects across Encino, Malibu, Bel Air, and Palos Verdes. We’ll walk through your site’s regulatory constraints and what they mean for your project — no obligation.
This article provides general educational information about construction and building in the greater Los Angeles area. It does not constitute legal, insurance, financial, engineering, architectural, or construction advice. Every property, insurance policy, and situation is unique.
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Verify our license: cslb.ca.gov — License #B-991385 · Last reviewed: May 21, 2026 · Information current as of publication date and subject to change.