Hillside Home Care: Drainage, Access & Retaining Walls

Own a hillside home in Sherman Oaks? The views are incredible, but rain, steep access, and aging walls can turn small issues into big repairs. You want a safe, stable property that shows well and holds its value. This guide breaks down drainage must-dos, driveway and emergency access rules, and retaining wall basics, including permits, costs, and timelines specific to Los Angeles. Let’s dive in.

Know the local hillside rules

Sherman Oaks is within the City of Los Angeles, so LADBS, LAFD, and the Los Angeles Zoning Code apply. In designated hillside areas or where grading exceeds 5,000 cubic yards, the City treats the work as engineered grading that typically requires geotechnical input and plan check. Review the City’s process on the LADBS Grading Permits page to understand when soils reports and engineered plans are required. You should also verify the zoning limits on wall count and height before you sketch any design.

• Check grading thresholds in the Los Angeles Municipal Code. LAMC grading rules outline when engineered grading is required.
• Review local retaining wall limits. In hillside areas the Zoning Code generally allows one freestanding wall up to 12 feet, or two up to 10 feet each if separated by at least 3 feet, with landscaping plans required for walls 8 feet or taller. See L.A. Zoning Code Section 12.21 for specifics.
• For LADBS plan check, geotechnical reports, and permits, start here: LADBS Grading Permits.

Get drainage right first

Water is the number one driver of slope movement and wall failure. When runoff concentrates or saturates backfill, the pressure behind a wall can spike and push structures out of alignment. The U.S. Army Corps of Engineers highlights hydrostatic pressure as a common failure trigger for retaining structures. Designing surface and subsurface drainage correctly will protect your slope and your investment.

• Keep roof runoff controlled. Clean gutters and downspouts before the rainy season and send water to an approved dispersal area or drainage device, not over the slope or behind a wall.
• Manage surface flows. Use swales, berms, and positive slopes so water moves to an approved discharge point. Avoid concentrating flows over bare soil.
• Include subsurface drainage behind walls. A drainage blanket, perforated collector pipe, and weep outlets that discharge to a safe location reduce hydrostatic pressure.
• Consider LID features with care. The City promotes on-site capture and infiltration, but hillside sites often need a geotechnical review before using dry wells or rain gardens. See the City’s Low Impact Development manual overview for context.
• For background on why drainage matters, see the USACE guidance on retaining walls. Review the USACE retaining wall manual.

Plan safe access and emergency access

Driveways, gates, and turnarounds on hillside lots must support everyday use and emergency response. The Los Angeles Fire Department sets minimum widths, clearances, and gate requirements so fire apparatus can reach your home. If you need to work in the public way for access or staging, separate City permits are required.

• Fire and gate standards. The LAFD details minimum widths that often start at 20 feet for access roads and may allow narrower residential driveways, plus gate setbacks and emergency opening hardware. Review LAFD gate and fire access requirements.
• Work in the public way. Curb cuts, driveway aprons, staging equipment, and traffic control often require Bureau of Engineering permits. Start with the BOE permit overview to understand A, B, E, and R permits. Explore BOE permits and approvals.

Retaining walls: types and permits

Not all walls are equal. Some are decorative, while others are structural and must be engineered and permitted. On hillside lots, most permanent walls that retain meaningful heights or carry extra loads require geotechnical and structural design.

• When permits are needed. Walls that retain more than about 4 feet or support a surcharge, such as a driveway or structure, typically need engineered design and building permits in Los Angeles. Learn more about when walls are considered engineered elements from this overview on permanent versus temporary retaining walls.
• Common wall types. Gravity walls rely on mass, segmental block walls often use geogrid reinforcement, concrete and CMU walls are common for higher loads, and anchored or tied-back walls are used where space is limited. Your engineer will match the wall type to your soils, loads, and access.
• Remember zoning limits. Wall count and height in hillside areas are capped unless you obtain discretionary approvals. Review Zoning Code Section 12.21 before you design terraces.

Costs and budgeting in Los Angeles

Prices vary with height, materials, drainage, site access, and engineering. Recent California guides show wide ranges that reflect the complexity of hillside work.

• Small garden walls under 3 feet can be relatively affordable.
• Structural residential walls around 3 to 6 feet with proper drainage often run about 80 to 160 dollars per linear foot.
• Complex engineered walls over 6 to 8 feet, or those with tiebacks or limited access, can run 150 to 250 dollars per linear foot or more, plus reports, engineering, and permit fees. See typical ranges in this California retaining wall cost guide.

Project steps and timelines

A clear plan will save time and reduce surprises. Most hillside projects follow a similar path, from early checks through final inspection.

1. Do a quick zoning and hillside check, and look up any past permits. Confirm wall height and count limits early.
2. Hire a licensed geotechnical engineer to review soils and slope stability and to provide design parameters.
3. Have a civil or structural engineer design the wall and drainage. Coordinate with LAFD if changing gates or access and with BOE if any work touches the public way.
4. Submit your LADBS plan check for grading and building permits and obtain any BOE right of way permits needed.
5. Build with required inspections for soils, steel, and drainage and close permits with final sign offs.

Simple, low walls can move quickly. Engineered hillside walls often take several weeks to months for design and plan check, then days to weeks for construction depending on access and complexity.

Seasonal maintenance checklist

• Clear gutters and downspouts before and after the rainy season.
• Keep downspout outlets, weep holes, and drain outlets free and flowing.
• Walk your walls after storms and look for new cracks, bulges, or seepage.
• Avoid adding heavy loads near the edge of slopes or behind walls without engineering input.
• Use irrigation modestly on slopes and avoid saturating planter beds that sit atop walls or near slope crests.

When to call a pro

Call a licensed geotechnical or structural engineer if you see bulging or leaning, horizontal or stepped cracking, new settlement, persistent wet spots, or blocked weep holes. Many failures occur during or after heavy storms, so a prompt review can prevent larger damage. For contractors, always verify license, insurance, and references and get several written bids. Use the state’s CSLB license check before you hire anyone.

Ready to buy or sell a hillside home in Sherman Oaks and want a plan that protects your value? Reach out to Arthur Aslanian for neighborhood-savvy guidance and a trusted network of engineers and contractors.

FAQs

What permits do I need for a retaining wall in Sherman Oaks?

• In the City of Los Angeles, permanent walls that retain significant heights or support extra loads typically require LADBS plan check, geotechnical reports, and building or grading permits; start with the LADBS Grading Permits guide.

How tall can a retaining wall be in L.A. hillside areas?

• The Zoning Code generally allows one freestanding wall up to 12 feet or two up to 10 feet each if they are separated by at least 3 feet, with landscaping plans for walls 8 feet or taller; see Zoning Code Section 12.21.

What are the driveway and gate rules for emergency access?

• LAFD standards set minimum widths and clearances and require gates that allow emergency opening and proper setbacks; review the LAFD access and gate requirements.

How should I handle stormwater on a hillside lot?

• Use positive surface grading, swales, and approved discharge points, and include subsurface drainage behind walls; for on-site capture, consult the City’s Low Impact Development manual overview and get geotechnical input.

How much does a retaining wall cost in Los Angeles?

• Recent California ranges show about 80 to 160 dollars per linear foot for many 3 to 6 foot structural walls, and 150 to 250 dollars per linear foot or more for complex engineered walls; see this statewide cost overview.

When does a wall need engineered design and permits?

• Walls that retain more than about 4 feet or support a surcharge usually require engineering and permits in Los Angeles; a helpful primer is this note on engineered retaining walls.