Thinking about opening up your hillside home or adding a new level but unsure how the rules apply on a slope? In Los Angeles, the Baseline Hillside Ordinance can shape everything from your square footage to how much dirt you can move. You want a smooth remodel, predictable costs, and a plan that passes review the first time. This guide breaks down the BHO in plain English so you can design smart, avoid delays, and protect your budget. Let’s dive in.
BHO basics in Los Angeles
The Baseline Hillside Ordinance sets special development standards for single family homes on lots inside the City’s mapped Hillside Area. It changes how floor area, grading, height, and stories are calculated to fit homes to steep terrain. You should always confirm the current text of LAMC Section 12.21(C)(10) before you design. You can review the ordinance history and updates through the City Council file for the BHO. See the City Clerk record.
If your property is zoned R1, RS, RE, or RA and is within the Hillside Area, the BHO likely applies. Major remodels and additions must meet BHO standards, while minor work may be treated differently. LADBS uses BHO-specific plan check corrections to verify compliance, so expect targeted BHO review. Review the BHO plan check sheet.
How the BHO shapes your design
Residential floor area limits
BHO rules redefine what counts as Residential Floor Area on a hillside lot. Some spaces are exempt or partially exempt, and ceiling height can affect what counts. Getting the RFA calculation right early helps you understand how much you can add by right. See BHO calculation concepts.
Basement rules that matter
Basements in the hills are not the same as basements on flat lots. To qualify for an RFA exemption, most of the basement perimeter must be at or below specific exposure limits, often described as no more than 3 feet above adjacent grade for at least 60 percent of the perimeter. You cannot use retaining walls to raise grade to meet the test. If a basement contains habitable rooms, it may be counted as a story. Review LADBS hillside basement guidance.
Grading and haul routes
The BHO limits by right grading quantities. Projects that exceed by right caps or propose large import or export of soil can require deviations, haul route approvals, public notice, and hearings. Numeric thresholds have changed over time, so confirm current limits for your address and slope band. A published case discusses how grading limits and amendments have been interpreted in practice. Read the grading case overview.
Import and export are tightly regulated in the hills. Haul route approvals can add conditions like truck size, hours, staging, and bonds for street repairs, and they add time to your process. The City’s HCR and grading code outline when hearings and conditions apply. See haul route and grading code provisions.
Height, stories, and slope bands
Height and story limits depend on slope band analysis and the way your home steps with the hillside. Expect to provide a topographic survey and slope band map prepared by a licensed professional. This analysis helps set your buildable envelope and whether a level qualifies as a story. Review BHO envelope concepts.
Driveways and substandard hillside streets
Lots on narrow hillside streets face special access rules. Minimum paved widths, connectivity, and driveway grading limits can affect feasibility and may require extra approvals or fees. Address these early to avoid redesigns. Check BOE and BHO access clearances.
Other key clearances
Plan check routes your project to multiple agencies. Tree protection, drainage and stormwater, sewer connection within 200 feet, and Fire Department access are common review items. Missing a single clearance can pause permit issuance. See the City’s BHO clearance workflow.
Who reviews your project
LADBS manages plan check, grading permits, and geotechnical approvals. City Planning handles zoning determinations and any discretionary deviations. BOE reviews sewer, street work, and import/export bonding, while DOT, BSS, and LAFD weigh in on traffic, streets, and fire access. Expect a multi-agency process that moves in stages.
If you need a haul route or grading deviation, count on public notice and hearings. In some cases, environmental review can apply. Bonding for import or export may be required before permits are issued. Review import/export bonding procedures.
Your submittal checklist
- Topographic survey and slope band analysis to define height, story, and envelope.
- Geology and soils report, plus structural plans for foundations and retaining walls.
- Drainage, erosion control, and landscape plans as required by plan check.
- RFA calculations, including basement exposure diagrams if you plan a lower level.
- Grading quantities and a haul route package if import or export approaches thresholds.
These items are commonly required and often drive design changes. Having them ready helps you resolve corrections faster. Geotechnical scope is especially critical on steep lots.
Common pitfalls to avoid
- Misclassifying a lower level as a basement. Apply the hillside exposure test correctly and avoid using retaining walls to raise grade. Review basement rules.
- Underestimating grading and haul route impacts. Big exports can trigger hearings, conditions, and weeks of extra time. See code provisions for haul routes.
- Assuming broad exemptions. Driveway, remedial grading, and foundation exemptions are narrow and documented. Check BHO plan check guidance.
- Skipping early Fire and BOE coordination. Sewer availability and fire access can hold up permits. Review BHO clearances.
A simple game plan
- Confirm your lot is within the City’s mapped Hillside Area and note your zone. A quick map review helps you avoid wrong assumptions.
- Engage your architect and engineer early. Ask for a preliminary RFA and basement exposure check before you fall in love with a layout.
- Get a topo survey and slope band analysis. This sets your realistic height, story count, and envelope.
- Estimate cut and fill. If you are near common thresholds, plan for a haul route, bonds, and neighbor outreach.
- Build in time for corrections or hearings. Multi-agency plan check can take several rounds.
- Verify the latest rules for your address. Review LAMC Section 12.21(C)(10) and recent updates. See the City Clerk record.
Make a confident hillside remodel decision
A successful hillside remodel in Los Angeles starts with accurate rules, a right-sized design, and a clean submittal. If you are weighing upgrades before listing or buying a hillside property with remodel potential, a clear plan can protect your timeline and value. For strategic guidance on which improvements pay off and how to position your property, connect with Active Realty, Inc..
FAQs
What is the BHO and when does it apply in Los Angeles?
- The Baseline Hillside Ordinance sets special development standards for single family homes on lots within the City’s mapped Hillside Area, and it applies to new construction, major remodels, and additions in hillside R1, RS, RE, and RA zones.
How are basements treated under the BHO?
- A lower level must meet strict exposure limits to be considered a basement for RFA exemption. If exposure exceeds limits or the space has habitable rooms that qualify it as a story, that area may count toward RFA and story limits.
When do I need a haul route approval for a hillside remodel?
- If your project’s import or export of earth exceeds by right limits, you will likely need a haul route approval, with conditions on trucks, routes, hours, and bonding that add time to your project.
Who can grant deviations from BHO grading limits?
- A Zoning Administrator or other designated decisionmaker can grant deviations after required findings and a public hearing, which adds time and public notice to your process.
What studies should I budget for before I design?
- Plan for a topo survey, slope band analysis, geology and soils report, structural foundation design, drainage and erosion control plans, and grading takeoffs. These items shape your design and are commonly required during plan check.
