Cost to install LA french drain?

$4K–$12K typical perimeter drain.

Basement waterproofing in LA?

$15K–$35K for a full interior-exterior system.

Does the Baseline Hillside Ordinance kill my ADU?

Almost never. State ADU law overrides local FAR limits up to 800 sqft, and many hillside lots can fit a full 1,200 sqft attached ADU even under BHO.

How much does hillside geotech add?

Plan on $8–25k for the report itself. The downstream cost — caissons, retaining walls, deeper foundations — is where the real budget impact lives.

Hills & Canyons Drainage & Waterproofing.

LA drainage — french drains, area drains, downspout extensions, sump pumps. Hillside homes get engineered solutions.

Hill parcels add the Baseline Hillside Ordinance, geotech, and (along the ridgeline) the Mulholland Scenic Parkway Specific Plan to every permit package. The ADU itself is still ministerial, but plan-check takes longer because the structural, grading, and haul-route sheets are heavier than a flat-lot project.

Hills & Canyons cost band — 2026

$4K – $35K

Surface french drain bottom; full basement system top.

Hills & Canyons permit clock

12–18 weeks ministerial

3–7 days for typical drainage system.

Scope — start to keys.

Site assessment
Engineering if needed
Permit
Excavation + install
Backfill + test

What changes about the permit here.

BHO caps height to ~33 ft and limits grading cuts based on lot slope.
Soils / geotech report required on any slope >10%.
Hillside Construction Regulation permits gate haul-route hours and truck size.
Beverly Hills + Bel-Air HOA / R1 design review runs parallel to building permit.

What moves the Hills & Canyons number.

Slope-driven foundation work commonly $80–250k above flat-lot equivalent.
Crane / pump days run 2–4× a Valley job — narrow streets and switchbacks.
Caissons on steep slopes can hit $1,500–4,000 per linear foot of depth.
Beverly Hills design review pushes cladding budgets up sharply.

In short.

Cost to install LA french drain?: $4K–$12K typical perimeter drain.
Basement waterproofing in LA?: $15K–$35K for a full interior-exterior system.
Does the Baseline Hillside Ordinance kill my ADU?: Almost never. State ADU law overrides local FAR limits up to 800 sqft, and many hillside lots can fit a full 1,200 sqft attached ADU even under BHO.
How much does hillside geotech add?: Plan on $8–25k for the report itself. The downstream cost — caissons, retaining walls, deeper foundations — is where the real budget impact lives.

More we build in Hills & Canyons.

Drainage & Waterproofing in nearby LA areas.

Got a Hills & Canyons project in mind?

Send us the address and we’ll pull Hills & Canyons zoning, setbacks, and drainage & waterproofing feasibility before you spend on drawings.

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