Everything homeowners ask about building an ADU in Henderson — answered with 2026 data.
Yes, ADUs are allowed in the RS (RS-1/2/4/6/8), RM (RM-10/16), RH (RH-24/36), MC and MN districts, not RMH, MR or any commercial or industrial district, subject to use-specific standards and no conditional use permit (“S” in Table 19.9.1-2, current through Ord. 4171 eff. 8/21/2026; standards at Sec. 19.9.4.B.6) in Henderson, NV. The maximum size for a detached ADU is the greater of 25% of the principal dwelling's floor area or 1,000 sq ft, a guaranteed minimum, not a cap (Sec. 19.9.4.B.6.b.ii). Tiny-house ADUs max 400 sq ft excluding lofts; an attached garage doesn't count toward ADU size. The separate accessory-structure cap (greater of 10% of the lot or 50% of the home's livable area, Sec. 19.9.3.C.4.b) also applies to all accessory buildings combined. Attached ADUs can be up to the greater of 25% of the principal dwelling's floor area or 1,000 sq ft, the same rule as detached ADUs. Henderson has an ADU-friendliness score of 7/10. Check our full Henderson ADU rules page for complete zoning details.
ADU construction in Henderson typically costs $110,000-$260,000. The cost per square foot averages $180-$330. Garage conversions are more affordable at $50,000-$120,000, while prefab ADUs cost $80,000-$180,000. Permit fees add No ADU line in the DSC fee schedule (eff. 10/1/2025). Closest rows: Accessory Building - Residential at 1,000 sq ft = $1,303 plan check + $1,266 inspection (MPE included); Single-Family Addition at 1,000 sq ft = $1,601 + $1,555. Confirm the fee category at intake. to your budget. See our detailed Henderson ADU cost guide.
Detached ADUs in Henderson can be up to the greater of 25% of the principal dwelling's floor area or 1,000 sq ft, a guaranteed minimum, not a cap. Attached ADUs are limited to the greater of 25% of the principal dwelling's floor area or 1,000 sq ft, the same rule as detached ADUs. Junior ADUs (JADUs) have a cap of not a separate category; an ADU built within the primary residence follows the same greater-of-25%-or-1,000 sq ft rule (Sec. 19.9.4.B.6.a defines detached, attached and internal ADUs together). Maximum height is No explicit height cap in the ADU standards; height instead drives setbacks at a 14-ft threshold (Sec. 19.9.4.B.6.b.i). RS primary buildings cap at 35 ft (Table 19.2.2-1) and residential accessory structures at 24 ft (Sec. 19.9.3.C.4.c); confirm with the Planning Division which applies to a detached ADU. You are allowed up to 1 accessory dwelling unit per lot on a qualifying lot.
Rear setback: 5 ft for a detached ADU 14 ft or less in height; taller ADUs must meet the main house's rear setback (RS-1/RS-2: 25 ft; RS-4/RS-6/RS-8: 15 ft; RM: 10 ft; RH: 15 ft). Detached ADUs need 6 ft of separation from other buildings, or a connecting roof at least 10 ft wide (Sec. 19.9.4.B.6.b.i). Side setback: Interior side: 5 ft for a detached ADU 14 ft or less in height; taller ADUs meet the main house's (RS-1/RS-2: 10 ft; RS-4/RS-6/RS-8: 5 ft; RM: 5 ft; RH: 10 ft). Corner side always matches the main house's (RS-1/RS-2: 15 ft; RS-4/6/8: 10 ft). Front setback: Must match the principal dwelling's front setback (RS-1/RS-2: 20 ft; RS-4/RS-6/RS-8: 10 ft; RM/RH: 10 ft, Table 19.2.2-1). An ADU in the front or corner side yard must match the main house's materials, roof and color (Sec. 19.9.4.B.6.b.v). Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
1 off-street space per ADU (Sec. 19.12.3 residential parking table, current through Ord. 4171), at Nevada AB 396's ceiling, which bars local ordinances from requiring more than one space for an ADU. 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; no owner-occupancy condition appears in the ADU standards (Sec. 19.9.4.B.6), making Henderson the Las Vegas Valley exception. Occupancy follows the Code's “family unit” rule (Ch. 19.37): any number of related people, or up to 6 unrelated people. The ADU may not be sold apart from the main house (19.9.4.B.6.b.vi). 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 Henderson is typically Not published for residential permits. The DSC offers over-the-counter review for qualifying permits and an expedited-review option; ask at intake for the current turnaround. Plan check: Plan check is priced with inspection in DSC Table A (eff. 10/1/2025) and includes mechanical, plumbing and electrical review: $1,079 at 200 sq ft, $1,164 at 600 sq ft, $1,303 at 1,000 sq ft for a residential accessory building. Planning-side fees, if needed: Design Review $274, Administrative Adjustment $164, Zoning Verification Letter $109 (eff. 8/1/2025). Pre-approved plans availability: No city pre-approved ADU plan program identified as of September 2026 (none on the Community Development checklists and handouts page).
Average ADU rental income in Henderson: 1-bedroom units rent for $1,350-$1,900/month, 2-bedroom units for $1,600-$2,250/month. Short-term rentals: Not addressed in the ADU standards. Rentals under 30 days are a separate use (“S” in RS/RM/RH) governed by Sec. Expected ROI: 5-7% return on cost.
The minimum lot size for an ADU in Henderson is None for ADUs. District minimums govern lot creation only (Table 19.2.2-1: RS-1: 40,000 sq ft; RS-2: 20,000; RS-4: 10,000; RS-6: 6,000; RS-8: 4,000; RM: 3,000), so a typical 6,000 sq ft RS-6 tract lot qualifies. 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 Henderson, a garage conversion typically costs $50,000-$120,000. 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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