ADU Before & After in Westchester, CA
We’ve been designing, permitting, and building ADUs across Westchester since 2015. These are the actual conditions we walk into, the decisions we make, and the finished spaces we hand over. Every project below includes a written price before work started and a documented photo record at each phase, per Haven Standard Clause 1.
Recent Transformations
Garage Conversion ADU - Over-Height Foundation & Sloped Driveway
The existing slab was 2.5 inches at the alley edge, sloped for drainage that no longer served any purpose. L.A. Building Code requires 3.5 inches minimum for residential bearing, plus vapor barrier under conditioned space. We broke out the entire slab, regraded with compacted base, and poured new with embedded radiant tubing for future heating. The client received a 23-photo record showing rebar layout, compaction test, pour, and rough inspections. Written price was $127,000 before any work started. Final permit was signed off March 2024.
New Detached ADU - Corner Lot with Zero-Setback Constraints
Corner lots in Westchester trigger LAMC Section 12.21C.10’s zero-lot-line provisions, which most designers miss until plan check. We modeled the easement corridor in the initial site plan and specified a 12-foot-wide footprint to maintain 3-foot clear on both sides of the utility run. The client had two prior rejections from LADBS for encroachment. We resubmitted with a revised plot plan and got approval in 7 weeks. Prefab shell from Plant Prefab, coordinated under our single contract. Total project: $198,000, written at signing. Photo record: 31 images from excavation to final.
Junior ADU - Shared Wall with Sound Transmission Issues
The client wanted rental income without losing the bedroom’s character. Junior ADUs require owner occupancy of either main or JADU unit per California Government Code 65852.2, so we confirmed their intent to remain in the main house and documented it in the owner-occupancy affidavit. The real problem was the shared wall: original 1947 construction, no insulation, every refrigerator cycle audible. We specified a decoupled assembly - resilient channel, 5/8″ Type X, Roxul Safe’n’Sound, second layer 5/8″ - and tested with a calibrated meter at rough. STC-52 achieved. Written price: $74,500. The client now rents at $1,850/month, well above the $1,400 they projected.
ADU Site Prep & Utilities - Clay Soil and Failed Percolation
Westchester’s western blocks sit on the old Manchester Flood Control Channel alluvium, and the clay holds water like a bathtub. The client’s previous contractor had proposed a standard spread footing without soils investigation. We brought in a geotechnical report, specified 18 inches of import fill with geotextile separation, and installed a perimeter French drain to daylight at the alley. The surcharge period added 3 weeks to schedule, which we built into the original timeline and price. No change order. Photo record includes every lift thickness and compaction test. Site prep only: $34,000, with foundation and utilities quoted separately at $61,000.
Garage Conversion ADU - Unpermitted Prior Work & Asbestos Siding
This is the scenario Nadia Ellery sees most often in Westchester’s post-war neighborhoods: a previous owner “finished” the garage in the 1980s, and now the current owner wants it legal for rental. The asbestos-cement siding triggered Cal-OSHA notification requirements, so we brought in a certified abatement contractor for removal and disposal, documented with waste manifest. The unpermitted electrical was entirely replaced; no grandfathering applies when you change occupancy to residential. We pulled a full permit as new construction rather than alteration, which actually simplified inspection sequencing. Written price: $156,000 including abatement. The client received 47 photos, the waste manifest, and the final signed Certificate of Occupancy.
New Detached ADU - Prefab Coordination with LADBS Plan Check
The client specifically wanted a prefab unit for schedule certainty. We specified Abodu based on their approved LADBS master plan, which shaves 4-6 weeks off plan check versus a custom design. The ficus roots required a root-pruning plan with arborist sign-off, which Abodu’s standard foundation detail didn’t address. We modified the pier specification to clear the critical root zone and submitted the arborist report as a deferred submittal. One contract covered factory coordination, site prep, crane rental, utility tie-in, and finish. Written price: $245,000. The unit was set on a Tuesday, final inspection passed 11 days later. Photo record includes crane lift, set, and utility pressure test.
Want Results Like These?
Every project starts with a free estimate, written before any work begins, with no call-for-pricing runaround. If you already have a written estimate from another studio, we’ll give you a free second opinion. A live person answers at (213) 698-7591, 24/7. Or schedule your site visit and we’ll show you exactly what your property’s constraints are, what the code requires, and what it costs to get it done right.
Written by Nadia Ellery, Owner at Ellery ADU Studio Westchester, serving Westchester since 2015.