ADU Builder in Calabasas Highlands, Calabasas

Slope Comes First on a Calabasas Highlands ADU

Homes in the Highlands were fitted into the hillside rather than built on graded tract pads. The house often sits on the only level ground, with the yard falling away behind it or rising sharply toward the next street. Before we talk about floor plans, we figure out where a unit could physically stand and what it would take to hold it there.

That usually means a topographic survey and a soils report. The geotechnical engineer's findings set the foundation type, whether stepped footings, grade beams or drilled piers, and spell out how high any retaining wall can go. The answer sometimes rules out a backyard cottage entirely. It just as often points to a smarter location, like the side yard beside the garage or the space under an existing deck.

Fire Hazard Severity Zone Rules for Highlands ADUs

Brushy canyon slopes surround this community, and the City asks owners to check their parcel against the CAL FIRE map published for Calabasas in March 2025. Where a lot falls in the Very High zone, a new ADU must follow wildland-urban interface construction: Class A roofing, ignition-resistant cladding, ember-resistant vents and fire-rated glazing. Defensible space around the new unit is part of the deal.

Fire matters for planning in less obvious ways too. Fire department review may look at how an engine reaches the unit and how far the nearest hydrant is. Sprinklers may be required. We bring those questions to the start of design so they shape the layout instead of forcing changes later in plan check.

ADU Types That Suit Calabasas Highlands Homes

On many Highlands lots the most cost-effective unit uses space the house already has. A junior ADU of up to 500 square feet inside a lower level or a converted attached garage needs no new foundation. An attached ADU that extends the house along its existing pad avoids cutting a new one into the hill, and state law allows attached units to reach 25 feet or the zone's limit, whichever is lower.

A detached unit is still possible where the lot has a natural bench or an old building pad. The City's standards table limits detached ADUs to one story and 16 feet, as quoted by the state in 2026, so a freestanding unit here stays low and compact. That can actually help on a slope, since a single-story building is lighter and easier to support.

Building Logistics on Highlands Streets

Narrow, winding roads limit what trucks and equipment can reach. Concrete pumps, drill rigs for piers and lumber deliveries all need a plan for where they park and how long they block the street. On steep driveways, materials may have to be moved by hand or by a small track loader. We sort out staging before construction starts so neighbors are not surprised.

Utilities take the same planning. We check how the house connects to sewer and water, how deep the lines run and whether a unit below the house would need a pump to move waste uphill. Las Virgenes Municipal Water District serves Calabasas, and Southern California Edison provides power along these hillside streets.

City of Calabasas Permits for Highlands ADUs

Calabasas Highlands lies inside city limits, so the City's Planning Division reviews zoning and the Building and Safety Division issues the permit. Hillside projects add grading review and, when the soils report calls for it, geotechnical review. State law still requires ministerial approval and sets the 60-day decision clock once the application is complete. Because HCD found the City's ADU ordinance out of compliance in May 2026, we confirm which local standards are in force when you submit.