ADU Construction in Hawthorne
Hawthorne ADUs with a bathroom planned around one wet wall, drain lines kept clear of footings and shear walls placed where pipes will not cut them.
The bathroom of a Hawthorne ADU has to work in a small footprint, with a shower, toilet and vanity sharing a single wet wall so the drain lines stay short. That wall also matters to the structure. Pipes running through it cannot cut the hold-down straps or the sheathing of a braced panel, so the engineer places shear walls on the other sides and the wet wall stays free for plumbing.
Drains under the slab
Before the slab is poured, drain lines for the shower, toilet and sink are laid in trenches and tested with a standing column of water, and the inspector signs off before concrete goes in. We keep those trenches clear of the perimeter footing, or the engineer details a sleeve where a line has to pass through. The shower gets a sloped pan with a waterproof membrane that turns up the walls. Steam leaves through a fan ducted to the roof, switched by a humidity sensor so the room dries after each use.
A bathroom built for daily use
We frame blocking into the shower walls for future grab bars, size the doorway for easy passage and keep the shower threshold low. Tile goes over cement board or a foam backer board. Hawthorne's building department reviews the plumbing layout with the rest of the drawings, and the inspector checks the drain test and the shower pan before walls close. Hot water comes from a heat pump unit or a tankless heater, sized to serve the bathroom and kitchen together.
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Typically a reinforced slab on thickened perimeter footings, sized from a soils report. A Hawthorne unit's slab carries the drain lines below it, so trenches are planned around the footings. If the soil is expansive, the engineer may add steel or depth. Bolts and hold-downs sit in place, checked by the inspector, when the concrete arrives.
Where the garage footing is deep and sound, it can stay. We dig beside a Hawthorne garage to measure it. A new bathroom means cutting the old slab for drain lines, so we also check whether the slab is thick enough to patch cleanly. Weak footing sections are replaced before the new shear walls go in.
Hawthorne units qualify for the package at 500 square feet or under, on one level. For Hawthorne, the floor plan showing the bathroom, the wet wall and the braced panels around it ties plumbing to structure, and it comes in the package. Larger or two-story designs get priced after a lot review.
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Describe the house and what it needs. We look at the structure first and send the quote in writing.