ADU Construction in Hermosa Beach, Separated by Design
Hermosa Beach ADUs attached to the house or built over a garage, with the rated wall and floor separation plan check looks for drawn from the start.
When a Hermosa Beach ADU shares a wall or a floor with the main house or a garage, plan review traces a fire-rated separation between them from the foundation to the roof sheathing. The reviewer wants that line unbroken, with every pipe, wire and duct that crosses it sealed with a listed firestop. Drawing that separation clearly is how an attached or over-garage unit clears review and how it protects both homes.
Building the rated wall or floor
A rated wall between units is usually framed with layers of fire-rated gypsum board on each side, sometimes over resilient channels that also cut sound. Over a garage, the floor and ceiling assembly gets the same treatment, and the garage side carries thicker board. Doors through the separation are solid core or steel, self-closing and tightly gasketed. The attic above is split along the same line, so a fire on one side cannot travel through the roof space to the other. Each assembly is called out by its tested listing.
Openings and penetrations
Electrical boxes on a rated wall are offset, or they get putty pads behind them, so the wall stays intact. Plumbing that crosses gets a firestop collar or a listed sealant. Ducts that pass through get fire dampers where required, though we prefer to route them so they never cross at all. Outside, the same idea carries on: stucco or fiber cement on the walls, listed vents at the eaves and tempered glass in every window, so heat from a fire on either building finds no easy way in.
ADU Construction in Hermosa Beach: common questions
Hermosa Beach plan review checks each parcel against the fire hazard maps when an ADU is filed, and only a mapped parcel must meet the wildfire chapter. We still specify noncombustible cladding, listed vents and tempered glazing, which pair naturally with the rated separation an attached unit already needs.
A Hermosa Beach set for an attached or over-garage unit relies on the wall drawings, where the rated assemblies and firestop details are spelled out, and on the site plan, which also notes whether the parcel lies in the coastal zone. Our package fits a qualifying unit of a single story, and a unit stacked over a garage is scoped separately.
Possibly, if the lot allows it and the city signs off on the sequence for the rebuild. Building the unit into the new house from the start lets the rated separation be framed in one sequence, which is cleaner than retrofitting it into a finished structure, and the two can share one permit path if the city allows.
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Tell us about the house and the adu construction work. We reply about a walk-through and a written scope.