Journal ·
Santa Clarita Hillside Lots: When Slope and Grading Trigger City Review
In the City of Santa Clarita, hillside development review applies to a parcel whose average cross slope is 10 percent or more. City staff handle projects on slopes between 10 and 15 percent, or with grading from 100 to under 1,500 cubic yards. Slopes over 15 percent, or grading over 1,500 cubic yards, go to a Planning Commission hearing. Work within 100 feet, vertically or horizontally, of a designated significant ridgeline needs a ridgeline alteration permit, which goes to both the Planning Commission and the City Council.
When does Santa Clarita require hillside development review?
Section 17.23.130 of the Santa Clarita Municipal Code sets the procedure. Subsection B applies it to "parcels of land having average cross slopes of ten percent (10%) or more." Subsection C then splits the work between two levels of authority.
Subsection C.1.c also carves out small projects. Minor grading, or work limited in scope such as yard areas for a pool or spa, landscaping, additions to existing structures and accessory structures, may be approved by the director through a grading or building permit without hillside development review.
The standards that a reviewed project must meet sit in a different chapter, section 17.51.020, which covers density by slope, contour grading, architecture and landscaping. Section 17.23.130 traces to Ordinance 13-8, adopted June 11, 2013.
Staff review or a Planning Commission hearing?
This is the split in subsection C of 17.23.130, read side by side with the city's own application checklists and the planning fee schedule.
| Trigger | Who decides | Hearing | Fee |
|---|---|---|---|
| Average slope over 10% and under 15% | Director, Class II | No public hearing | $4,268 |
| Grading of 100 to under 1,500 cubic yards | Director, Class II | No public hearing | $4,268 |
| Average slope over 15% | Planning Commission, Class IV | Yes | $5,970 |
| Grading over 1,500 cubic yards | Planning Commission, Class IV | Yes | $5,970 |
| Work in the Ridgeline Preservation overlay | Planning Commission, then City Council, Class V | Two hearings | $13,699 |
The grading rows apply to parcels that already meet the 10 percent slope test; on a flat lot, grading volume alone does not bring hillside review.
The Class IV checklist lists hillside development review for "parcels >15% Average Cross-Slope" among the applications that need public notice and a Planning Commission hearing. The Class II checklist lists it among applications that need no notice or hearing unless otherwise stated. The first page of the fee schedule shows an effective date of August 24, 2026. Its second page, where the ridgeline fee sits, still carries an August 25, 2025 header, so confirm that fee at the counter.
Subsection C.2.c adds one more route to the Commission: a project that already includes a Class IV, V, VI or VII application goes there whatever its slope.
Where the code's thresholds do not line up
The thresholds are written in more than one place, and the wording differs. These gaps are worth raising with the planner at the start.
- Exactly 10 percent. Subsection B of 17.23.130 says "ten percent (10%) or more" and 17.51.020 says "ten percent (10%) or greater," while subsection C.1.a gives the director slopes "greater than ten percent." Grading sections 17.86.040 and 17.86.060 also say "greater than ten percent."
- Exactly 15 percent. C.1.a covers slopes "less than fifteen percent" and C.2.a covers slopes "greater than fifteen percent." A lot averaging exactly 15 percent fits neither sentence.
- Exactly 100 cubic yards. The director's tier starts at grading "equal to or exceeding" 100 cubic yards, while 17.86.040 brings in hillside rules for grading "involving more than" 100 cubic yards.
How the planning division reads these edges is not written in the code, so the answer for a borderline lot comes from staff.
How is average cross slope calculated?
Section 17.51.020(B)(2) gives the formula:
Average Cross Slope = I x L x 0.0023 / A
Here I is the contour interval, L is the contour length (in practice the combined length of the contour lines within the site), A is the site area in acres, and 0.0023 is the constant the code describes as converting square feet to acres and slope to percent. A worked illustration with made-up numbers: on a 0.25 acre lot mapped at 2 foot contours, with 600 feet of contour line in total, the result is 2 x 600 x 0.0023 / 0.25, or about 11 percent. That lot would sit in the director's tier.
The city expects the calculation, with its data, in the application, so it is worked from topographic mapping, not from a listing. The city's site plan and exhibits checklist asks for "Average cross slope calculations of the lot (show formula and data used)" along with grading quantities for excavation, fill, import and export.
What changes on a lot near a ridgeline?
Section 17.38.070 creates the Ridgeline Preservation overlay. It protects the area within 100 feet vertical and 100 feet horizontal of a designated significant ridgeline. The general locations are on the adopted ridgeline map on file in the Planning Division.
Subsection B reaches further than many buyers expect. Any development near a generally designated significant ridgeline, "including but not limited to grading permits, building permits and land use entitlements," must submit an exhibit by a licensed civil engineer, using site-specific topographic mapping, that fixes the ridgeline's position against the proposed work. Under subsection D.1, no engineered slopes, structures, streets, utilities or other manmade features are allowed in the overlay without a ridgeline alteration permit.
That permit is a Class V application. The city's Class V checklist describes public hearings before the Planning Commission and the City Council, and it states that the decision of the City Council is final. The submittal includes topography maps, average cross slope calculations, ridgeline location exhibits and preliminary grading plans.
Subsection B also lets the director, at their discretion, exempt a project when all three apply: the property has since been significantly disturbed, those disturbances were permitted, and the area is substantially urbanized.
When is a grading permit needed at all?
Section 17.81.010 requires a grading permit from the City Engineer, with listed exceptions. An excavation of no more than 50 cubic yards is exempt if it is less than 2 feet deep, or if it does not create a cut slope taller than 5 feet and steeper than 2 horizontal to 1 vertical. A fill that supports no structure and blocks no drainage course is exempt if it is under 1 foot deep, under 3 feet deep and no more than 50 cubic yards, or under 5 feet deep and no more than 20 cubic yards, each with slope limits.
A permit exemption is not a free pass. The section says an exemption does not authorize work that violates the chapter or any other city law.
What the hillside standards ask of a design
Section 17.51.020 asks that cut and fill slopes be shaped to appear similar to the existing natural contours. It bars graded or cut embankments steeper than 2 to 1 next to a publicly maintained right-of-way. Where a structure is within public view, subsection C.3.b requires a minimum rear setback of 15 feet from the top of slope and/or an average of 15 feet from the edge of the pad.
Subsection E of 17.23.130 lists eight findings, on top of the general findings in section 17.06.130, that the approving authority has to make, from conserving natural topography to limiting the effect on view corridors. A house plan that ignores the grade gives the reviewer little to work with on those findings.
A pre-offer checklist for a Santa Clarita hillside lot
| Question | Where the answer comes from |
|---|---|
| Is the parcel inside city limits or unincorporated county land? | City and county maps; the rules above are city rules |
| What is the average cross slope? | Topographic survey with the 17.51.020 formula |
| How many cubic yards will the plan move? | Grading quantities from a civil engineer |
| Is the lot near a designated significant ridgeline? | Ridgeline map at the Planning Division |
| Did a prior owner grade or build under an approved hillside review? | City permit and entitlement records |
| Are oak trees on or near the work area? | Oak tree survey; separate permit rules |
Unincorporated communities next to the city follow Los Angeles County rules instead; the difference is covered in the city limits versus county guide. Oak trees carry their own permit track, described in the Santa Clarita oak tree guide. Survey and grading figures belong in the due diligence on the buyer's page.
Q: Does a pool on a sloped lot need hillside review?
Not necessarily. Subsection C.1.c of 17.23.130 lets the director approve limited work such as pool or spa yard areas through a grading or building permit without hillside review. The grading permit rules in 17.81.010 still apply.
Q: I am selling a hillside home. What records help?
An approved hillside review, a recent topographic survey and the grading permit file answer a buyer's first questions, and they are worth having for a home valuation and the materials on the seller's page.
This article is general information drawn from the Santa Clarita Municipal Code and City of Santa Clarita Planning Division publications, not legal or engineering advice. Codes and fees change, and a specific parcel can carry conditions not discussed here. Confirm current requirements with the Santa Clarita Planning Division. Call Alla at (818) 699-5367 or use the enquiry form.
Looking at homes in Santa Clarita? Start with the Santa Clarita area guide and current Santa Clarita listings.