Burbank Grading Plan: SB9 House with 34-Foot Slope

If you own a sloped lot in Burbank and are trying to add a second unit under SB9, you already know the planning review is not simple. The city wants to see exactly how you are handling grade change, drainage, and retaining walls before they sign off. That is where we come in.

We recently wrapped up a conceptual grading plan for a Burbank SB9 (Senate Bill 9 allows two-unit developments on most single-family lots in California) 2-story residential project. The lot drops 34 feet from front to rear over 300 feet of depth. There is an existing house at the top of the slope. The new construction sits at the bottom, where we were working with roughly 9 feet of elevation change between the existing grade and the proposed finished floor for a 2-story house with a 3-car garage.

This one required some creative engineering to make it work.

The Site Challenge: A 34-Foot Slope Over 300 Feet

The existing house is at the top of the slope, accessed by a long driveway coming up from the street at the bottom. The new house sits at the bottom with a 3-car garage that ties into that existing driveway apron.

Burbank planning division wanted to see how we were handling the grade change. Specifically, they asked for conceptual grading plans that show existing vs. proposed elevation contours, finished pad elevations, and quantification of all cut and fill areas.

How We Designed the Garage Level

We cut into the slope to align the garage floor with the driveway approach, creating a smooth entrance without requiring a massive retaining wall structure. There are grade breaks involved, but the transition works.

From the garage level, seven steps get you up to the front door elevation. This is a common approach when you have a steep lot and need to get from garage to living level without an elevator or ramp.

Blending Into the Existing Topography

The rear corner of the house is at the East property line. The neighbor’s grade is higher there, so we needed to blend the new construction into the existing slope without creating a tall wall.

We used a short 2.5-foot max height wall along the East property line. This blends into the neighbor’s grade and keeps the retaining wall manageable. It also avoids having to get into a dispute about tall walls on the property line.

Drainage Approach

The conceptual grading plan shows rough flowlines and area drains that collect into PVC pipes. The pipes run to a catch basin, which outlets stormwater through the curbface onto the street flowline.

This is a fairly standard approach when you have a lot that slopes toward the street. Gravity takes the water down, the area drains collect it, and the catch basin provides the outlet through the curb.

Cut/Fill Depths and TIN Exhibit

Burbank planning also wanted to see the cut/fill depths. We created a TIN surface (a 3D model of the site’s existing and proposed topography) to calculate the volume between existing and proposed grades. The earthwork exhibit shows cut and fill depths across the site, which is what Burbank planning wanted to see.

We also provided sections showing the slope relationships through the site. Sections help visualize what the finished grade looks like in profile, which is harder to see in plan view alone.

Services Provided

This Burbank SB9 project required three things to get through planning pre-screen review:

• Grading plans — Conceptual design showing how we shaped the pad and handled the 34-foot elevation change across the lot.
• Cut/fill depth exhibit — A TIN surface (3D model of the site) showing exactly how much earthwork the project requires.
• Section views — Profile diagrams showing slope relationships in detail so Burbank planning could see the finished grade in cross-section.

Burbank planning approved the conceptual approach, and we moved into detailed design.

For Burbank residential projects with steep slopes, we can look at your specific site and tell you what Burbank planning will require before you submit.

No obligation. Just useful information if you are early in the process and trying to figure out what you actually need.