Quick Answer
The Baseline Hillside Ordinance (LAMC § 12.21 C.10) is a Los Angeles zoning ordinance that caps maximum floor area for single-family hillside lots on a sliding scale tied to lot size, slope, and street width, sets a defined grade point for measuring building height, and limits grading quantities. It is a zoning-envelope requirement, distinct from the engineering-level grading and retaining wall permit process reviewed by LADBS's Grading Division. It applies to mapped hillside neighborhoods across the city, including the Hollywood Hills, Laurel Canyon, Bel Air, and Mount Washington.
Homeowners planning a new hillside home, a significant addition, or even a modest remodel in one of Los Angeles's sloped single-family neighborhoods often discover a frustrating fact partway through design: the lot's zoning doesn't tell the whole story. A separate ordinance — the Baseline Hillside Ordinance — can cap the buildable square footage well below what a standard zoning lot-coverage calculation would suggest.
This is a genuinely different question from "how do I get my grading and retaining walls approved" — that's an engineering review handled by LADBS's Grading Division and covered in detail in our hillside grading and retaining wall permit guide. The Baseline Hillside Ordinance operates one level up, at the zoning envelope: how much floor area the lot is legally allowed to carry, how tall the building can be, and how much earth the project can move — before engineering details like retaining wall design even enter the picture.
This guide walks through what the ordinance actually regulates, which neighborhoods it covers, how LADBS verifies compliance during plan check, and the specific mistakes that most often delay hillside projects under it. This is general informational guidance — always confirm current numeric thresholds, slope-category boundaries, and grade-point methodology directly with LA City Planning or LADBS for your specific parcel.
Why the Ordinance Exists
The Baseline Hillside Ordinance responds to long-running community concern in Los Angeles's hillside neighborhoods about "mansionization" — homes built to a scale disproportionate to their lot and surrounding streetscape — and about grading operations that moved more earth than a given parcel could safely or reasonably support. Before the ordinance, hillside lots were largely subject to the same general zoning framework as flat lots, which didn't account for the specific ways slope, narrow streets, and limited fire-access affect what a hillside neighborhood can safely and appropriately absorb.
The ordinance layers hillside-specific floor-area, height, and grading standards on top of the underlying single-family zoning, so that a lot's buildable envelope reflects its actual slope, street capacity, and neighborhood context — not just its raw square footage.
What the Ordinance Actually Regulates
Maximum floor area. The ordinance ties a hillside lot's maximum floor area to lot size on a sliding scale, and in most cases further adjusts that base allowance according to the width of the street serving the lot and the parcel's slope category. A wider street or a gentler slope category generally supports a larger floor-area allowance than a narrow, steep hillside street — meaning two lots of identical square footage in different parts of the hills can have meaningfully different buildable floor areas.
Height, measured from a defined grade point. A sloped lot has no single obvious ground elevation the way a flat lot does, so the ordinance establishes a specific methodology for determining the reference grade point (or points) from which building height is measured. This prevents a design from artificially lowering its apparent height by measuring from a selectively chosen low point on an irregular site, and it is one of the more technical calculations in the entire ordinance.
Grading quantity limits. The ordinance caps how much cut and fill a hillside project can undertake, generally scaling the allowable quantity with the size of the lot rather than applying one flat citywide number. This is meant to keep grading proportionate to the parcel rather than allowing large-scale earthwork disproportionate to a lot's actual footprint.
Garage and parking configuration. Hillside development is subject to specific covered parking requirements reflecting the reality that many hillside streets have little or no on-street parking capacity. Haul route approval. Where grading requires exporting or importing earth beyond a set threshold, LADBS requires haul route approval — reviewing the proposed trucking route for street width, grade, and neighborhood impact — before a grading permit can be issued.
Which Hollywood Hills-Area Neighborhoods Does This Cover?
The Baseline Hillside Ordinance applies to properties zoned and mapped within the City of Los Angeles's hillside area designation. This generally includes many of the city's sloped single-family neighborhoods: the Hollywood Hills (including Laurel Canyon, Nichols Canyon, Mount Olympus, and Outpost Estates), Beverly Glen, Bel Air, Benedict Canyon, Mandeville Canyon, and Mount Washington, among other hillside communities across the city.
Not every parcel that "feels" hillside is necessarily mapped that way, and boundaries are determined parcel by parcel rather than by neighborhood name. We confirm mapped hillside status and the applicable slope category directly with LA City Planning or LADBS for each specific address before treating a project as BHO-governed. For a deeper look at how hillside jurisdiction and fire-hazard requirements interact in one of the most affected neighborhoods, see our Hollywood Hills permit expediting guide.
Illustrative Floor-Area Tiers by Lot Size
The table below illustrates, in general terms, how the ordinance's sliding-scale approach tends to track with lot size across representative hillside neighborhoods. These figures are illustrative examples of how the tiers relate to one another — they are not official LADBS or Planning figures, and the actual formula includes slope-category and street-width adjustments not reflected in a simplified lot-size table.
| Lot Size Tier | Representative Areas | General Note |
|---|---|---|
| Under 15,000 sq ft | Smaller hillside lots common in denser canyon streets such as parts of Laurel Canyon and Nichols Canyon | Generally the most restrictive floor-area allowance per lot; narrow street width often applies an additional reduction |
| 15,000–30,000 sq ft | Mid-size hillside parcels typical of many Hollywood Hills and Mount Olympus streets | Floor area typically scales up with lot size but remains subject to slope-category and street-width adjustments |
| 30,000–60,000 sq ft | Larger hillside parcels found in parts of Beverly Glen, Benedict Canyon, and Mandeville Canyon | Higher base allowance, but larger grading quantities on bigger lots can still trigger haul route review |
| Over 60,000 sq ft | Estate-sized hillside parcels, more common in Bel Air and upper Mandeville Canyon | Largest base floor-area allowance under the sliding scale; site-specific slope and access constraints still apply |
Illustrative categories for general orientation only — not official figures. Confirm the exact current floor-area formula, slope-category boundaries, and street-width adjustments for your specific parcel directly with LADBS or LA City Planning before relying on any calculation for design purposes.
How LADBS Verifies BHO Compliance — And How It Interacts With Grading Review
For hillside projects, LADBS generally requires specific zoning-compliance documentation — typically a floor-area and height calculation exhibit demonstrating the project fits within the ordinance's envelope — submitted alongside the architectural and structural drawings during plan check. This BHO-specific zoning review is administratively distinct from the engineering review LADBS's Grading Division and Geology and Soils Engineering Section perform on a project's grading plan, foundation design, and retaining walls.
In practice, this means a hillside project has to clear two related but separate hurdles: the zoning-level BHO compliance check (floor area, height, grading quantity ceiling) and the engineering-level grading and geotechnical review that determines whether the specific grading and retaining wall design is structurally sound and permittable. A project can pass one review and still have open corrections on the other — for example, a design that fits within the BHO's floor-area cap can still need a geotechnical report revision if the actual soil conditions differ from initial assumptions, or a project with excellent geotechnical findings can still need to reduce floor area if its BHO calculation was based on an incorrect slope category.
Because these tracks are distinct but tightly linked — grading quantity limits under the BHO directly cap how much earthwork the grading engineer can propose, for instance — we manage both as a coordinated submittal rather than treating one as secondary to the other.
Common, Real Reasons Hillside Projects Get Delayed Under the BHO
Floor-area miscalculation. The most common issue we see is a floor plan finalized before the BHO's floor-area envelope was correctly calculated for the parcel — often because an outdated formula, an incorrect slope category, or the wrong street-width classification was used. Discovering this after a full architectural set is complete means redesigning under time pressure rather than designing within a known envelope from day one.
Grading quantity overages. A grading plan that looked reasonable in early concept design can exceed the BHO's allowable grading quantity once the geotechnical engineer's final cut-and-fill numbers are calculated, particularly on lots requiring a garage cut into the slope or a basement level. Because grading quantity limits and haul route thresholds are linked, an overage here can also unexpectedly trigger haul route review the project team hadn't planned for.
Height datum errors. Because the ordinance's grade-point methodology for height measurement is technical and site-specific, a preliminary design based on an incorrectly established grade point can appear compliant on paper and then fail plan check once LADBS verifies the correct reference points against the actual surveyed topography — sometimes forcing a redesign of upper floors or roof massing late in the process.
The BHO Compliance Process — Step by Step
From confirming hillside status to final sign-off, here is how Baseline Hillside Ordinance compliance moves through design and LADBS review.
- 01
Confirm Hillside Area & Slope Category
Verify with LA City Planning or LADBS that the parcel falls within the mapped hillside area, and confirm the specific slope category and street-width classification that apply — these determine which point on the BHO's sliding scale the lot falls under.
- 02
Calculate the Floor-Area Envelope
Before design work is finalized, calculate the maximum floor area the lot supports under the current BHO formula, incorporating any slope or street-width adjustments. This calculation should be treated as a hard design constraint, not a number to verify after the floor plan is drawn.
- 03
Establish the Reference Grade Point
Work with your architect and surveyor to establish the ordinance's defined grade point (or points) for height measurement on the specific topography of the lot, since this determines the maximum allowable building height and is a common source of plan check correction when miscalculated.
- 04
Scope Grading Quantities Against the BHO Limit
Coordinate with your civil and geotechnical engineer to estimate cut and fill quantities early, and check them against the ordinance's grading limit for the lot. Where quantities approach or exceed the limit, the design may need to be revised before a full plan set is prepared.
- 05
Prepare BHO Compliance Documentation
Prepare the floor-area and height compliance exhibits LADBS requires to verify Baseline Hillside Ordinance compliance as part of the plan check submittal, alongside the architectural and structural drawings.
- 06
Submit to LADBS Plan Check
Submit the complete package to LADBS. For projects also requiring grading or retaining wall work, this BHO compliance review runs alongside — but separately from — Grading Division and Geology and Soils Engineering Section review of the geotechnical and grading engineering.
- 07
Respond to BHO-Specific Corrections
Where LADBS issues corrections tied to floor-area calculation, grade-point methodology, or grading quantity, resolve them directly against the ordinance's current standard rather than assuming a prior project's approved calculation still applies.
- 08
Final Sign-Off & Certificate of Occupancy
Once BHO compliance, standard building plan check, and any grading/retaining wall sign-off are complete, LADBS can proceed to final inspections and Certificate of Occupancy issuance for the completed project.
Where This Overlaps With Fire-Hazard Construction in the Hills
Many BHO-governed hillside parcels also sit within a mapped Very High Fire Hazard Severity Zone, particularly in canyon areas like upper Laurel Canyon and Nichols Canyon that back onto open, brush-covered hillside. The BHO's floor-area, height, and grading requirements and Chapter 7A's ignition-resistant construction standards are entirely separate legal requirements that both apply to the same project — satisfying one does not satisfy the other, and a design has to work within the BHO's envelope while also using Chapter 7A-compliant roofing, venting, and exterior materials where the fire-hazard designation applies.
Our experience managing Chapter 7A compliance and multi-agency fire-hazard coordination for post-fire rebuild projects in Pacific Palisades and Altadena — and our work on hillside jurisdiction more broadly in communities like Topanga and Beverly Hills — carries over directly to BHO-governed hillside projects that also face fire-hazard construction requirements. Our related fire rebuild program covers this overlap in more detail for owners rebuilding on a hillside lot after a loss.
How Ocean Permits Manages BHO Compliance
Ocean Permits & Development is a women-owned Los Angeles permit expediting firm. We calculate a parcel's Baseline Hillside Ordinance envelope before architectural design is finalized — not after — so floor plans, height, and grading strategy are designed to fit the actual allowance rather than discovered to exceed it mid-plan-check. Where a project also needs grading, retaining wall, or geotechnical review, we coordinate that engineering-level track alongside BHO zoning compliance as one managed submittal, consistent with our broader LADBS permit process approach and our work on hillside ADU permitting.
For the engineering side of a hillside project — grading plans, retaining wall structural review, and geotechnical coordination — see our companion hillside grading and retaining wall permit guide. All initial consultations are free. Call +1 (213) 277-8777 or submit a project inquiry online.
Common Questions About the Baseline Hillside Ordinance
What is the Baseline Hillside Ordinance?
The Baseline Hillside Ordinance, codified at Los Angeles Municipal Code Section 12.21 C.10, is a citywide zoning ordinance that regulates how much floor area a single-family hillside lot can support, how building height is measured on sloped terrain, and how much grading a hillside project can undertake. It was adopted to address community concerns about oversized homes overwhelming the scale of hillside neighborhoods and about grading operations disproportionate to the lot they served. It sits on top of the underlying single-family zoning that would otherwise apply to the parcel.
How is this different from a grading or retaining wall permit?
The Baseline Hillside Ordinance and a hillside grading/retaining wall permit are related but distinct. The BHO sets the zoning-level envelope — how much floor area, height, and grading quantity a lot is legally allowed to have. A grading permit and any associated retaining wall structural review are the engineering-level process LADBS's Grading Division uses to review and approve the actual earthwork and wall design for a specific project, informed by a geotechnical report. A project has to satisfy both: it must fit inside the BHO's zoning envelope, and its grading and retaining wall engineering must separately pass Grading Division and structural review. See our dedicated guide to the grading and retaining wall permit process for that engineering-level track.
Which Los Angeles neighborhoods does the Baseline Hillside Ordinance apply to?
The ordinance applies to properties within the City of Los Angeles that are zoned and mapped within the city's hillside area designation. This generally covers many of the city's sloped single-family neighborhoods, including areas within and around the Hollywood Hills, Laurel Canyon, Nichols Canyon, Mount Olympus, Beverly Glen, Bel Air, Benedict Canyon, Mandeville Canyon, and Mount Washington, among others. Whether a specific parcel is inside the mapped hillside area — and exactly which BHO standards apply to it — should be confirmed directly with LA City Planning or LADBS using the parcel's address, since hillside boundaries and applicable standards are determined parcel by parcel rather than by neighborhood name alone.
How does the ordinance calculate maximum floor area?
The ordinance ties a hillside lot's maximum floor area to lot size, generally on a sliding scale, and in many cases further adjusts that allowance based on the width of the street serving the lot and the slope category the parcel falls into. Narrower streets and steeper slope categories typically correspond to more restrictive floor-area allowances. Because the exact calculation involves several interacting variables specific to a given parcel, and because the ordinance has been amended since its original adoption, we treat every floor-area calculation as parcel-specific and verify it directly against LADBS's current methodology rather than relying on a neighboring property's allowance or a generic formula.
How is building height measured on a hillside lot under the BHO?
Because a sloped lot has no single, obvious ground elevation, the ordinance establishes a defined method for calculating a reference grade point (or points) from which height is measured, rather than allowing height to be measured from an arbitrarily chosen or artificially lowered point on the site. This grade-point methodology is one of the more technical aspects of the ordinance and one of the more common sources of plan check correction when it is miscalculated or misapplied on a preliminary design.
Are there garage and parking requirements specific to hillside lots?
Yes. Hillside development is subject to specific covered parking and garage configuration requirements under the ordinance and related hillside development standards, reflecting the practical reality that many hillside streets have little to no on-street parking capacity and narrow rights-of-way. These requirements interact with the ordinance's grading limits when a garage requires cut into the slope to achieve a workable grade, which is a common design constraint on narrow hillside lots.
What triggers haul route approval under hillside development rules?
When a hillside project's grading plan requires exporting or importing a quantity of earth beyond a threshold LADBS applies, the project needs haul route approval for the trucking route before a grading permit can be issued. LADBS reviews the proposed route for street width, grade, and neighborhood impact. Because the Baseline Hillside Ordinance's grading limits and a project's actual haul route needs are closely linked, we evaluate both together early in design rather than discovering a haul route requirement after a grading plan is already finalized.
What are the most common reasons a hillside project gets delayed under the BHO?
The most common causes we see are a floor-area calculation performed incorrectly or based on an outdated formula before the design was finalized, a grading plan that exceeds the lot's allowable quantity once final engineering numbers are in, and a height calculation based on the wrong reference grade point. Each of these is discoverable — and correctable at far lower cost — if it's checked against the ordinance before architectural drawings are completed, rather than after a full plan check submittal comes back with corrections.
Does LADBS check BHO compliance separately from standard building plan check?
Baseline Hillside Ordinance compliance is generally verified as part of the plan check process for hillside projects, often requiring specific zoning-compliance documentation — such as a floor-area and height calculation exhibit — submitted alongside the architectural and structural plans. For projects also involving grading or retaining walls, this zoning-level BHO review runs alongside, but is administratively distinct from, LADBS's Grading Division and Geology and Soils Engineering Section review of the engineering itself. A project can satisfy one of these tracks and still have open items on the other.
Does the Baseline Hillside Ordinance apply to ADUs?
State ADU law limits how much a city can restrict accessory dwelling units, including in some cases limiting the application of local ordinances like the BHO to ADU square footage. However, site-specific hillside conditions — grading needed for a foundation, retaining wall requirements, and the BHO's height-measurement methodology where it still applies — can still affect a hillside ADU project in practice. We evaluate every hillside ADU site individually rather than assuming state streamlining removes every hillside-specific technical consideration.
Is the Baseline Hillside Ordinance the same in every hillside neighborhood?
The ordinance's core structure — floor-area sliding scale, grading limits, and grade-point height measurement — applies citywide to mapped hillside areas, but specific numeric thresholds and some standards can vary by slope category, street width, and, in some cases, community plan area overlays. A calculation that applies correctly to a Hollywood Hills parcel should not be assumed to transfer directly to a Bel Air or Mount Washington parcel without independently verifying that lot's specific slope category and street classification.
How does the BHO interact with fire-hazard construction requirements in the hills?
The two sets of requirements are separate but frequently overlap on the same parcel. A hillside lot in a mapped Very High Fire Hazard Severity Zone has to satisfy the BHO's floor-area, height, and grading limits and separately comply with Chapter 7A ignition-resistant construction standards and defensible space requirements under Public Resources Code Section 4291. Neither requirement substitutes for the other, and a design that satisfies the BHO's floor-area envelope still needs its exterior materials, venting, and roofing reviewed against Chapter 7A where the fire-hazard designation applies.