Everything homeowners ask about building an ADU in Roseville — answered with 2026 data.
Yes, ADUs are allowed in CMU, R1, RS, R2, R3, and RMU zones with an existing primary residence; NC, CC, GC, HC, and CBD commercial zones if an existing residence has an approved CUP in Roseville, CA. The maximum size for a detached ADU is 850 sq ft (studio/1BR) or 1,000 sq ft (2+BR) per city handout — the state floor; minimum 150 sq ft. Attached ADUs can be up to 850 sq ft (studio/1BR) or 1,000 sq ft (2+BR); state law also guarantees up to 50% of the primary dwelling. Roseville has an ADU-friendliness score of 6/10. Check our full Roseville ADU rules page for complete zoning details.
ADU construction in Roseville typically costs $150,000-$300,000. The cost per square foot averages $250-$400. Garage conversions are more affordable at $80,000-$150,000, while prefab ADUs cost $120,000-$250,000. Permit fees add Per the city's Accessory Dwelling Units Fee Policy — confirm current amounts with Development Services at (916) 774-5332 to your budget. See our detailed Roseville ADU cost guide.
Detached ADUs in Roseville can be up to 850 sq ft (studio/1BR) or 1,000 sq ft (2+BR) per city handout — the state floor; minimum 150 sq ft. Attached ADUs are limited to 850 sq ft (studio/1BR) or 1,000 sq ft (2+BR); state law also guarantees up to 50% of the primary dwelling. Junior ADUs (JADUs) have a cap of 500 sq ft. Maximum height is New ADUs: standards applicable to the primary residence apply per city handout; state law guarantees at least 16 ft detached (18 ft near major transit or on multifamily lots) and 25 ft attached. Detached ADUs on multifamily lots: 16 ft per handout. You are allowed up to City handout: 1 ADU per single-family lot, plus a JADU when the detached new-construction ADU has 4-ft setbacks; multifamily lots: 2 detached ADUs + interior conversions up to 25% of units. State law (Gov. Code 66323) guarantees more combinations — this is part of HCD's compliance review on a qualifying lot.
Rear setback: 4 ft for new construction; none for conversions of existing structures (including same-footprint rebuilds). Side setback: 4 ft for new construction; none for conversions. Front setback: Underlying zone standards apply — confirm with Roseville Planning at (916) 774-5276. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
Conversions: none required. New structures: 1 space per unit or per bedroom (whichever is less), waived within 1/2 mile of transit, in Historic Old Town, for additions, or where permit-parking areas exclude ADU occupants; tandem/setback parking OK; no replacement parking for garage conversions. 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 ADUs. JADUs: city handout requires owner-occupancy; under AB 1154 (2026) enforceable only where the JADU shares a bathroom with the main home. 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 Roseville is typically 60-day state-mandated review; deemed approved if the city misses the deadline (SB 543, Jan 2026). Plan check: Standard building plan check; preapproved master plans reduce review time — confirm timing with the Building Division. Pre-approved plans availability: Yes — Preapproved ADU Plans program per AB 1332 (master plans preapproved for site-specific permit submittal).
Average ADU rental income in Roseville: 1-bedroom units rent for $1,700-$2,000/month, 2-bedroom units for $2,000-$2,350/month. Short-term rentals: No — rental terms must exceed 30 days; STR permits are not issued for ADUs or JADUs (Ch. 4.25). Expected ROI: 6-9% annual return.
The minimum lot size for an ADU in Roseville is No minimum lot size (density and lot-size limits do not apply to ADUs). 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 Roseville, a garage conversion typically costs $80,000-$150,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.