Everything homeowners ask about building an ADU in Long Beach — answered with 2026 data.
Yes, ADUs are allowed in Any lot with an existing or proposed single-family or multifamily dwelling in a residential zone, or in a mixed-use zone, planned development district or specific plan that allows residential use (Gov. Code 66314(d)(2); city ADU Zoning Summary sec. II); the city does not limit ADUs by zoning district. What you may build turns on lot type: a single-family lot (one or more detached houses and no multifamily building) gets the single-family menu, a multifamily lot (two or more units in one building or attached buildings) gets the multifamily menu, and a lot with both cannot cross-apply them (IB-PZ-001, Lot Types). Check your zone on the city's What's My Zoning District? map in Long Beach, CA. The maximum size for a detached ADU is 800 sq ft for a new detached ADU on a single-family lot (IB-PZ-001 Table 1, applying Gov. Code 66323(a)(2)(A)); ADU floor area is measured to the interior walls. On a multifamily lot a detached ADU has no size limit. Converting an existing detached garage or accessory building has no size limit either, but the only addition allowed is up to 150 sq ft for stairs or an entry. State law lets a city allow up to 1,200 sq ft (Gov. Code 66314(d)(5)), which the city's February 2025 summary did; if you want more than 800 sq ft on a single-family lot, ask the Planning Bureau (562-570-6194) before designing. Attached ADUs can be up to 50% of the primary home's floor area or 800 sq ft, whichever is more, counting only the new addition and not any converted part of the house. Long Beach has an ADU-friendliness score of 8/10. Check our full Long Beach ADU rules page for complete zoning details.
ADU construction in Long Beach typically costs $215,000-$400,000. The cost per square foot averages $310-$450. Garage conversions are more affordable at $90,000-$180,000, while prefab ADUs cost $90,000-$300,000. Permit fees add $5,500-$6,500 in city plan-check and permit fees for a 750-800 sq ft new ADU (derived from the Building Permit & Plan Check Fees effective 5/20/2026 and IB-077's $175.92 per sq ft R-3 valuation): combination building permit at 150% of the valuation-based permit fee ($1,264 for the first $100,000 of valuation plus $6 per $1,000 above, min $164), combination plan check at 85% of the permit fee (min $154), zoning plan check at 0.5% of valuation (min $310), NPDES at $2 per $1,000 plus 75% for plan check, a $115 processing fee per application, and 6% Technology and 6% General Plan surcharges on all applicable fees; expedited plan check costs 2x. The city's own guide: budget about 2% of construction cost for plan check, permits and inspections. Impact, school and sewer fees are extra to your budget. See our detailed Long Beach ADU cost guide.
Detached ADUs in Long Beach can be up to 800 sq ft for a new detached ADU on a single-family lot. Attached ADUs are limited to 50% of the primary home's floor area or 800 sq ft, whichever is more, counting only the new addition and not any converted part of the house. Junior ADUs (JADUs) have a cap of 500 sq ft, created only by converting part of the existing house or an existing attached garage; no addition is allowed for a JADU (IB-PZ-001 Table 1 note h; Gov. Code 66333(d)). Minimum 150 sq ft; an efficiency kitchen is required; it may share a bathroom with the main house. Allowed only on a single-family lot, never on a lot with a multifamily building. Maximum height is New detached ADU on any lot: 16 ft; 18 ft within one-half mile walking distance of a major transit stop or high-quality transit corridor (city ADU Height Exception Map) or where a multistory multifamily building already stands on the lot, plus up to 2 ft to match the main house's sloped roof (IB-PZ-001 Table 2; Gov. Code 66321(b)(4)). New attached ADU on a single-family lot: 25 ft or 2 stories, or the zone's height limit, whichever is less. Conversions keep the existing building height. Height is measured per LBMC 21.15.1330 and 21.15.1335. You are allowed up to Single-family lot: one conversion ADU on a qualifying lot.
Rear setback: 4 ft for new construction, measured to the centerline of the alley where the lot abuts one (IB-PZ-001 Table 3 note b). A converted or rebuilt existing building keeps its existing setback if the Building Official and Fire Code Official find it sufficient for fire and life safety. Side setback: 4 ft or the zoning district's side setback, whichever is less (IB-PZ-001 Table 3); conversions and same-footprint rebuilds keep the existing setback. Recorded utility easements and other recorded building restrictions still apply even where they exceed 4 ft. Front setback: The front (and street-side) setback of the zoning district; if there is no other way to fit an ADU of up to 800 sq ft on the lot, the ADU may encroach into the front setback to the minimum extent needed, subject to Building and Fire Code limits (IB-PZ-001 Table 3 note a). Conversions keep the existing setback. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
None required if any of these apply: the ADU is within one-half mile walking distance of any transit stop (ADU Parking Exemption Map); in a historic district; converted from part of the house or an accessory building; on-street permits are required on the adjacent street but not offered to the ADU occupant; a car-share vehicle is within one-half mile; the ADU is filed with a new house or apartment building where any of those apply; it is a JADU; or the lot is inside the Parking Exempt Area established by LBMC 21.41.175 (IB-PZ-001, Parking). Otherwise one space per ADU, which may be tandem or in the driveway (Gov. Code 66314(d)(10)). No replacement parking is required when a garage, carport or driveway space is converted or demolished for an ADU (66314(d)(11)). Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
Not required for an ADU (Gov. Code 66315). For a JADU the owner must live in the main house or the JADU only if the JADU shares a bathroom with the main house; a JADU with its own bathroom has no owner-occupancy requirement (IB-PZ-001; Gov. Code 66333(b) as amended by AB 1154, effective Jan 1, 2026). State JADU rules also call for a recorded deed restriction barring separate sale of the JADU (66333(c)). Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in Long Beach is typically up to 60 days by state law; the city publishes no typical review time. A completeness determination is due within 15 business days and approval or denial within 60 days of a complete application, or the ADU is deemed approved (Gov. Code 66317, SB 543); pre-approved-plan ADUs can be approved over the counter and permitted the same day. Plan check: Combination plan check (building, electrical, plumbing and mechanical in one review) at 85% of the building permit fee, min $154; expedited review at 2x halves the turnaround; each recheck is 50% of the permit fee, min $286. Bring the APP-001 application, a FORM-028 plot plan, the full plan set as a single PDF, a site-specific Title 24 energy report (CF-1R) and, for new construction, one Low Impact Development stormwater measure on the plans (IB-068). Fire sprinklers are required only if the main house has them (Gov. Code 66314(d)(12)); a new detached ADU generally needs rooftop solar under the California Energy Code, permitted separately; a PAADU submittal must show 200 A minimum electric service (IB-068). Pre-approved plans availability: Yes, but paused. The Pre-Approved ADU (PAADU) Program (Building & Safety IB-068, rev. 1/27/2025) offers single-story, detached, all-electric standard plans under 1,200 sq ft for new construction only; a site-specific submittal is reviewed over the counter and the permit can issue the same day. The plan approvals previously listed (an 800 sq ft single-story design in four foundation and patio variants) expired December 31, 2025, and the city says the program is currently undergoing changes with no plan list published as of June 2026; check the PAADU page or email PlanCheck.Counter@longbeach.gov before choosing a plan.
Average ADU rental income in Long Beach: 1-bedroom units rent for $1,800-$2,400/month, 2-bedroom units for $2,400-$3,100/month. Short-term rentals: No. Expected ROI: 6-10% gross rental yield (before taxes, vacancy and financing).
The minimum lot size for an ADU in Long Beach is No minimum lot size: state law bars a minimum-lot-size standard for ADUs (Gov. Code 66314(b)(1)), and the city applies no lot coverage, open space, floor area ratio, landscaping, street tree or permeability standard to ADU projects (IB-PZ-001). This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In Long Beach, a garage conversion typically costs $90,000-$180,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.
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