West Hills · Adu Construction
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“Parking replacement: the law changed in 2020. If your garage is within ½ mile of transit or in a single-family zone, you do NOT have to replace the parking you're removing with the garage conversion. This is a common contractor myth that deters homeowners from projects that would otherwise pencil out financially. Check your specific parcel at LADBS.org.”
Specify your HVAC system early: a mini-split heat pump is almost always the correct choice for a garage conversion ADU, not an extension of the main house duct system. The mini-split gives the ADU independent climate control, doesn't affect the main house HVAC balance, and is energy-efficient. Budget $3,000–5,000 for the unit and installation.
Garage Conversion in Project Adu West Hills typically runs 5–15% above the greater LA average due to local labor market conditions and LADBS permit processing. Get 3 competitive bids from CSLB-licensed contractors who have completed recent projects in Project Adu West Hills or adjacent neighborhoods for the most accurate pricing.
Project timelines for garage conversion in Project Adu West Hills depend on LADBS permit processing time (4–16 weeks for most residential projects) plus construction duration. Total timeline from first contractor meeting to project completion: 3–9 months for most residential scopes. Projects in fire zones or on hillside lots in Project Adu West Hills may run 20–30% longer due to additional permit review.
This West Hills homeowner wanted to convert their detached 2-car garage into a one-bedroom accessory dwelling unit for an aging parent. The 440-square-foot garage had a standard 4-inch slab, no insulation, open stud walls, and a single 100-amp sub-panel with four circuits.
NP Line Design designed the ADU with a combined living room and kitchenette along the front wall, a full bathroom with walk-in shower in one corner, and a bedroom with a closet in the rear. The separate entrance faces the backyard with a small concrete porch and ADA-compliant ramp for accessibility.
The existing slab was adequate for the conversion but required trenching for new plumbing drain lines — a 3-inch kitchen drain and 4-inch bathroom drain connecting to the main house sewer lateral. A new 100-amp sub-panel was installed with dedicated circuits for kitchen appliances, HVAC, bathroom, and lighting. A mini-split heat pump (Mitsubishi 12,000 BTU) provides heating and cooling.
Walls were framed with 2x4 studs and insulated with R-15 fiberglass batts. Ceiling insulation is R-38 blown cellulose. All windows are dual-pane low-E vinyl meeting Title 24 U-factor requirements for Climate Zone 9. The kitchenette includes full-size appliances: 24-inch induction range, 10-cubic-foot refrigerator, dishwasher, and microwave. Flooring is luxury vinyl plank throughout. The LADBS permit process took 6 weeks including plan check corrections for the setback calculation.
The garage was located 3 feet from the rear property line, which triggered LADBS setback review under the ADU ordinance. While California AB 68 allows reduced setbacks for ADU conversions, the fire-rated wall assembly had to be upgraded to a 1-hour fire-rated wall with 5/8-inch Type X drywall on the property-line side. This required a specific wall section detail on the architectural plans that many plan checkers scrutinize carefully. The sewer lateral connection also required a cleanout installation at the property line per LADBS requirements, and the existing lateral had unknown condition after 40+ years of service — risking a costly surprise if it was collapsed or root-infiltrated.
NP Line Design prepared the setback documentation as part of the initial permit application, including the 1-hour fire-rated wall assembly detail (5/8 Type X drywall both sides, R-15 batt, fire-caulked penetrations) clearly noted on the architectural plans. This proactive approach avoided a plan check correction cycle that typically adds 2-3 weeks. For the sewer connection, we videoscoped the existing lateral before submitting the permit application and confirmed it was in serviceable condition with no root intrusion. We installed a two-way cleanout at the property line and connected the new ADU drains with proper slope. The project was completed in 4 months including the 6-week permit phase.
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ADU costs in LA range from $75,000 for a garage conversion to $350,000+ for a detached new-build ADU. Garage conversions are the most cost-effective option. NP Line Design provides free ADU feasibility assessments.
ADU projects in LA typically take 3 to 8 months including permits. Garage conversions are faster (3-5 months) while detached new-build ADUs take 5-8 months. Permit processing adds 4-8 weeks.
Yes. All ADUs require LADBS building permits including plan check, structural review, and Title 24 energy compliance. California state law (AB 68, SB 9) has streamlined the ADU permit process, but permits are still mandatory.
Yes. California law allows garage-to-ADU conversions in all residential zones. The converted garage must meet building code for habitable space including insulation, ventilation, plumbing, and electrical. NP Line Design specializes in garage-to-ADU conversions.
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