Slope Band Analysis

Slope Band Analysis is the methodology the Baseline Hillside Ordinance uses to calculate the maximum allowable Residential Floor Area on a hillside lot. The lot is divided into slope bands — strips of the lot where the ground slope falls within defined ranges — and each band’s area is multiplied by a corresponding RFA Ratio. The sum of those products is the lot’s maximum RFA. The methodology is map-driven, and the map underlying it is a survey deliverable, not a designer-prepared document.

LAMC §12.21 C.10(b)(1) for the Slope Analysis Map and methodology. Tables 12.21 C.10-2a and 12.21 C.10-2b for the RFA Ratios per slope band per zone. Table 12.21 C.10-3 for the Guaranteed Minimum Residential Floor Area path under §12.21 C.10(b)(2). PC/STR/Corr.Lst.107A Part II.A.1 for the plan-check requirement, with the Guaranteed Minimum exemption note at Part II.A.1.a.

A correction that the Slope Analysis Map is missing, that the map is not stamped and signed by a registered civil engineer or licensed land surveyor, that the map has not been approved by the Department of City Planning, or that the RFA totals shown on the plan sheets do not match the slope-band math. Plan check may also flag a project that claims the Guaranteed Minimum exemption without showing the math that the project actually fits the exemption.

Proceeding to design under an assumed RFA before the slope analysis returns, on the assumption that the survey will confirm what the designer has guessed. The slope analysis may return a substantially different number, and the design typically has to be reconciled with that number rather than the other way around. A second common pattern is treating the Guaranteed Minimum exemption as a default rather than as a conditional path that requires the project to fit specific criteria.

The Slope Analysis Survey could take several weeks to procure, and the City Planning approval timeline may add additional time. Projects that need the slope-derived RFA path typically benefit from commissioning the survey at the feasibility stage rather than at submittal, so the design may be sized to the actual cap rather than an assumed one. Where the Guaranteed Minimum applies, the exemption path could shorten the timeline substantially — but only when the project genuinely fits the exemption.

Residential Floor Area (the total that the slope-band methodology caps), Maximum Envelope Height under the BHO (which typically interacts with RFA distribution across the lot), Substandard Hillside Limited Street (where additional layer-changes may apply to grading and height), and Prevailing Setback (which may further reduce buildable area on the front of the lot independent of the RFA cap).

Verification: §12.21 C.10(b)(1) Slope Analysis Map provision confirmed at LAMC line 15429 area, including the requirement that the map be prepared, stamped, and signed by a registered civil engineer or licensed land surveyor and approved by the Department of City Planning. §12.21 C.10(b)(2) Guaranteed Minimum Residential Floor Area confirmed at LAMC line 15445 with the 800 sq ft floor and Table 12.21 C.10-3 reference. The City Planning Slope Analysis Survey form is referenced by name on PC/STR/Corr.Lst.107A Part II.A.1 but the form template was not uploaded for this draft and is therefore described role-only.