ADU Rules by City

Max size: No fixed cap for a permitted accessory dwelling. An ADU of 800 sq ft or the size of the primary dwelling (whichever is less) that meets design standards may cover more than 30% of the required rear yard (Ch. 3, Art. I, Sec. 4.D.32); a larger unit must stay within the 30%-of-required-rear-yard limit for accessory buildings (Sec. 6.A) and the district setbacks. · Setbacks: Accessory buildings may stand in the required rear yard but no closer than 3 ft to the rear lot line, or 5 ft where a garage door opens onto an alley; accessory buildings of 700 sq ft or less get half the district rear setback (min. 3 ft) (Ch. 3, Art. I, Sec. 4.D.5 and Sec. 6.A). District rear setbacks: D-3, D-4, D-5 15 ft; D-2 30 ft; D-1 40 ft (Table 1.03.101).

Max size: N/A: a detached accessory structure cannot be a dwelling (Sec. 73.5), may hold no plumbing beyond one laundry sink and/or one toilet (Sec. 3.1 'Accessory Structure'; a pool bath house up to 180 sq ft is the only exception) and may not contain a kitchen (Sec. 10.6.3). Accessory structures may cover at most 30% of the required rear yard and rise no more than 2 stories (Sec. 73.8.1). · Setbacks: N/A for ADUs (rear dwellings prohibited, Sec. 73.5). A non-dwelling accessory structure must sit at least 5 ft from all lot lines and 10 ft from any other structure on the lot (Sec. 73.8.1). Main-building rear yard: 45 ft in Residence 1 (Sec. 10.2.5); 25 ft for a two-family dwelling in Residence 2 (Sec. 13.2.2).

Max size: No ADU size cap is codified (the 1,000 sq ft / 50% draft rule was not adopted). A second unit must fit the district lot coverage: R-1 Urban 50%, R-1 Suburban 35%, R-2 Urban 50%, R-2 Suburban 40%, R-A 35% (Secs. 64-2-4 to 64-2-6) · Setbacks: District rear yard applies to any dwelling: R-1 Urban 5 ft, R-1 Suburban 8 ft, R-2 Urban 5 ft, R-2 Suburban 8 ft, R-A 10 ft (Secs. 64-2-4 to 64-2-6); Historic District Overlay (Art. 14) can override. No accessory-dwelling setback reduction is codified

Max size: The lesser of 75% of the gross floor area of the existing single-family dwelling or 1,000 sq ft (§28-33(a)(3)(A)); for this section gross floor area means the interior habitable area of the house or the ADU (§28-33(a)(3)(A)(I)), not the exterior-wall measure in §28-15. No more than two bedrooms (§28-33(a)(3)(G)). A detached ADU counts toward the district building coverage cap: 45% in R1-8 to R1-5, 40% R1-10, 20% R1-15, 30% RR-18, 15% AG/RR-43/R1-35 (§28-33(a)(3)(E); §28-35.A; §28-133(f)) · Setbacks: 5 ft from the property line (§28-33(a)(3)(D)(I)), against a house rear setback of 15-40 ft by district; state law caps what the city may require at 5 ft (A.R.S. §9-461.18(B)(6))

Max size: 75% of the gross floor area of the single-family dwelling on the same lot (§3.3.4.A.4) — a ratio with no separate square-footage ceiling, so a 1,500-square-foot ADU fits behind a 2,000-square-foot house. The state floor requires only the lesser of 75% or 1,000 square feet (A.R.S. §9-461.18(A)(3)), so Buckeye is more generous for houses over about 1,333 square feet. Gross floor area runs to the exterior faces of exterior walls, less underground parking, uncovered steps and balconies (§10.3) · Setbacks: 5 feet from the property line — the ADU exception to the district's principal-dwelling rear setback (§3.3.4.A.2), which otherwise runs 40 ft in AG, 30 ft in R1-43 and R1-18, 25 ft in R1-10, 20 ft in R1-6, 10 ft in R1-3, 8 ft in R1-1 and 15 ft in MF-1 (Table 4.1-1); state law bars the city from requiring more than 5 feet (A.R.S. §9-461.18(B)(6))

Max size: 75% of the single-family dwelling's gross floor area (interior habitable area) or 1,000 sq ft, whichever is less · Setbacks: 5 feet minimum (uninhabitable space attached to an ADU, e.g. a garage, must meet full district setbacks)

Max size: 75% of the primary home's gross floor area (interior habitable area), measured by LDC Section 2 'Gross Floor Area'. Up to 1,000 sq ft is by right; from 1,001 sq ft up to the 75% cap the unit needs a $1,000 Administrative Use Permit and must be inside the building envelope (LDC 5.2.3.4.c, 5.2.3.A-B). State floor: the lesser of 75% or 1,000 sq ft must be permitted (ARS 9-461.18.A.3). · Setbacks: 5 ft minimum for an ADU up to 10 ft tall; add 1 ft for every foot of height over 10 ft (a 13-ft unit needs 8 ft). Units of 1,000 sq ft or less may sit inside the rear setback area; units over 1,000 sq ft must stay within the building envelope, i.e. the district rear setback of 20-40 ft (LDC 5.2.3.A.1-2, 5.2.3.B.2). State cap: 5 ft (ARS 9-461.18.B.6).

Max size: Up to the gross floor area of the existing house, but never more than 1,000 sq ft (UDC §35.3.204.A.16; Ord. O25-45 changed 'square footage' to 'gross floor area'). Gross floor area is measured within the exterior walls (§35.8.004). This beats the state floor of the lesser of 1,000 sq ft or 75% of the house (A.R.S. §9-461.18(A)(3)), so a 1,000 sq ft casita is legal behind a 1,000 sq ft house · Setbacks: No less than 5 ft from the rear property line (UDC §35.3.204.A.11.a); the house itself needs 15–25 ft in the R1 districts, so the ADU may sit closer than the house. State law caps what the city may require at 5 ft (A.R.S. §9-461.18(B)(6)). A detached unit must also stand behind the front plane of the house and 6 ft (fire-rated) or 10 ft from it (§35.3.203.B.1, B.3)

Max size: The lesser of 75% of the gross floor area of the principal single-family dwelling or 1,000 sq ft (§3.12.3.A.8). Article 8 measures gross floor area from the exterior walls, excluding only underground parking, uncovered steps, portals and exterior balconies; the state statute's own definition is interior habitable area (A.R.S. §9-461.18(I)(2)) — ask the planner which figure they apply to your house · Setbacks: 5 ft (§3.12.3.A.5) — the ceiling state law allows (A.R.S. §9-461.18(B)(6)). The general accessory-building rule sends any building with sleeping facilities to the principal-building setbacks (§3.12.2.I.5 — 15 to 30 ft rear in the R1 districts), but §3.12.3 is the ADU-specific provision and matches the state cap; ask the planner to confirm in writing. Setbacks are measured to the roof overhang, not the wall (§3.12.2.J)

Max size: 75% of the primary residence's interior habitable area or 1,000 sq ft, whichever is less (11-31-3(C)); a 1,200 sq ft house allows up to 900 sq ft, a house of 1,334 sq ft or more allows the full 1,000. Since Ord. 5950 (Aug 2025) the ADU no longer counts toward the cap on combined detached accessory floor area in 11-30-17(A)(4). District lot-coverage and building-coverage limits still apply (11-31-3(E)). · Setbacks: 5 ft minimum for a new attached or detached ADU (11-31-3(D)(1)(a), as rewritten by Ord. 5950, effective Aug 2025). An existing detached building that meets the 11-30-17 accessory-building setbacks, or is legal non-conforming, can be converted to an ADU with no added setback; an expansion may follow the existing non-conforming line if it does not worsen it. Since Ord. 6025 a detached ADU must also sit at least 5 ft from the house, other ADUs and accessory buildings.

Max size: No square-foot cap. Two limits bind: all accessory buildings and structures together may not occupy more than one-half of the main building's ground area (§1005.A; Policy #53: first floor incl. covered patios and attached garage, overhangs excluded; Policy #59: wall face to wall face plus roofed patios and ramadas); and the guest house counts toward the lot's 25% floor area ratio in R-175 through R-18A, "inclusive of all areas under roof" (Table 1001-A1; FAR Certification handout rev. 6-29-26) · Setbacks: 20 ft in R-175 and R-43; 10 ft in R-35, R-35A, R-18 and R-18A; 7 ft in R-10 — rising to 40 ft (35 ft in R-18A, 20 ft in R-10) where the rear yard fronts a street (Table 1001B). Nothing in state law caps these: the 5-ft ceiling in A.R.S. §9-461.18(B)(6) binds only municipalities over 75,000 people. In R-10 an owner may instead use the setback on the recorded plat or as it existed at annexation, with documentation (Policy #50, rev. 9/20/17)

Max size: The lesser of 75% of the gross floor area of the existing single-family dwelling or 1,000 sq ft (Peoria City Code §21-316.C.2); 'gross floor area' means interior habitable area (§21-316.B). The ADU must be smaller than the house (§21-316.B definition) and counts toward the district's lot-coverage cap (§21-316.D.3) · Setbacks: 5 ft from the property line (Peoria City Code §21-316.D.2.a) — versus the 15-ft rear setback a house must keep in R1-18 through R1-6, 20 ft in R1-35 and 30 ft in R1-43 (§21-420.A). State law caps the ADU rear setback a city may require at 5 ft (A.R.S. §9-461.18(B)(6))

Max size: 75% of the primary home's gross floor area (interior habitable area), and no more than 1,000 sq ft on a lot of 10,000 sq ft or less; on a lot over 10,000 sq ft, the lesser of 3,000 sq ft or 10% of net lot area (ZO 706.A.8). A garage, carport or attached shade structure built as part of a detached ADU does not count toward its floor area but does count toward lot coverage · Setbacks: 3 ft from an interior rear lot line for a detached ADU; 0 ft along a fully dedicated alley (706.A.4.b). Attached ADU: the house's rear setback, or a projection to 3 ft if under 15 ft tall. State law caps any ADU rear or side setback at 5 ft (ARS 9-461.18.B.6)

Max size: First ADU on the lot: 1,000 sq ft or 75% of the existing main house, whichever is less (Sec. 7.900; ARS 9-461.18 measures interior habitable area). The second and any third ADU: 500 sq ft each. Every ADU needs a private outdoor living space at least 5 ft deep and 50 sq ft, and no more than 6 adults may live in the house and ADUs combined. · Setbacks: 5 ft for a detached ADU built in the rear yard as the Zoning Ordinance defines it (Sec. 7.900; ARS 9-461.18(B)(6) caps ADU side and rear setbacks at 5 ft). An attached ADU keeps the main house's district rear setback. A detached ADU must also sit at least 10 ft from the main house and from any other ADU on the lot.

Max size: The lesser of 75% of the gross floor area of the existing house or 1,000 sq ft (§106-11.3.A.2); gross floor area means interior habitable area (§106-11.2, adopting A.R.S. §9-461.18). The unit also counts toward the lot-coverage cap that applies to the house (§106-11.4.A.4): 45% on R-1 lots of 8,000-11,999 sq ft, 40% at 12,000-17,999 sq ft, 30% at 18,000-43,559 sq ft, 25% in RR and on R-1 lots of 1 acre or more (Tables 106-2b, 106-2c); no cap is listed for R-1 lots under 8,000 sq ft · Setbacks: No less than 5 ft from the property line (§106-11.4.A.3.a) — the ceiling state law allows (A.R.S. §9-461.18(B)(6)), against 15-30 ft for the house itself in R-1 (Table 106-2c). The unit must also sit at least 5 ft from any other structure (§106-10.3.A) and outside any existing or planned public utility easement unless every easement holder and affected utility consents in writing (§106-11.4.B)

Max size: Lots under 1 acre: 75% of the main house's gross floor area or 1,000 sq ft, whichever is less. Lots of 1 acre (43,560 sq ft) or more: 75% or 2,000 sq ft, whichever is less. Gross floor area is interior habitable area, excluding garages, carports and exterior storage (ZDC 3-402; ADU Development Guide Step 2). District lot coverage still applies, e.g. 45% in R1-6. · Setbacks: 5 ft minimum in all districts unless the district or overlay allows less (ZDC 3-402; ARS 9-461.18(B)(6)). Where the lot backs onto a dedicated public alley the rear setback is measured from the midpoint of the alley (city ADU page).

Max size: 75% of the gross floor area of the principal dwelling, not to exceed 1,000 sq ft of gross floor area; a casita may always be up to 650 sq ft regardless of the size of the main house (UDC 6.6.3.B.5). Gross floor area means interior habitable area (A.R.S. 9-461.18(I)(2)). Lot coverage in R-1, R-2 and R-3 is capped at 70% for single-family use (Table 6.3-2.A), and ADUs are exempt from the zone's maximum residential density (6.6.3.B.1) · Setbacks: 5 ft minimum from the rear property line (UDC 6.6.3.B.6), the ceiling allowed by A.R.S. 9-461.18(B)(6). Chimneys, roof overhangs and bay windows may project 2 ft into the yard as long as 3 ft remains (6.4.5.D.1). A casita cannot be built over a public utility easement without the utility's written consent (A.R.S. 9-461.18(E))

Max size: 1,200 sq ft of habitable area (Table 38-A), subject to AMC 18.04.080.020: all detached accessory structures on the lot combined may not exceed the main house's floor area or the zone's minimum livable floor area (1,700 sq ft in RH-1, RH-2, RH-3 and RS-1; 1,225 sq ft in RS-2, RS-3 and RS-4; required garage space not counted). An 800 sq ft ADU with 4-ft side and rear setbacks must be allowed regardless (Gov. Code 66321(b)). Minimum unit size 150 sq ft · Setbacks: 4 ft for any ADU (Table 38-A); a JADU follows the underlying zone. Converting a legally permitted structure needs no setback, and a legal accessory structure may be demolished and rebuilt as an ADU in the same location and dimensions without new setbacks (18.38.015.140). Eaves and roof overhangs must stay at least 12 inches from the property line

Max size: 1,200 sq ft outside the Hillside Overlay; 850 sq ft (studio/1-bedroom) or 1,000 sq ft (2+ bedrooms) within the Hillside Overlay · Setbacks: 4 ft minimum

Max size: 850 sq ft for a studio or one-bedroom; 1,000 sq ft with two or more bedrooms (BMC 10-1-620.3(F)(2)); 800 sq ft in the Mountain Fire Zone or when built in the front setback. One ADU per lot may add up to 120 sq ft per extra code-compliant on-site parking space, with a recorded deed restriction (F)(9). Any space over 12 ft in interior height, and attics over 5 ft, count double toward the cap · Setbacks: 4 ft, including an ADU above a garage (10-1-620.3(H)(1)); a legally permitted garage or accessory structure converted in place keeps its existing setback, with 4 ft applying to any added footprint (H)(3). Balconies or patios more than 7 in. above grade and second-story stairs also need 4 ft

Max size: 1,200 sq ft on a single-family lot; detached ADUs over 800 sq ft must also fit the zone's lot-coverage limit (IB-111, Aug. 2026). Mandatory-approval detached ADUs of 800 sq ft or less get 4-ft setbacks and may encroach into the front setback if nothing else fits (CMC 21.10.030.E). · Setbacks: 4 feet minimum for attached and detached ADUs (IB-111; CMC 21.10.030). A converted non-conforming garage or accessory structure may keep its existing setback, except in the Coastal Zone where it affects a geologic setback, view, access or habitat buffer.

Max size: 1,200 sq ft of floor area (Gov. Code 66314(d)(5), which the city applies directly; city ADU page). A detached ADU of up to 800 sq ft with 4 ft side and rear setbacks and 16 ft height cannot be blocked by lot coverage, floor-area-ratio or open-space limits (Gov. Code 66321(b)(3)). · Setbacks: 4 ft minimum for new construction; none for a conversion of an existing structure or a rebuild in the same footprint (Gov. Code 66314(d)(7)). The city imposes no minimum separation from the main house; the Building Division applies fire-rated wall rules instead (city ADU page).

Max size: Local option: 1,200 sq ft regardless of the primary home's size (§106.42.015.B.3.b), measured as interior livable space from the inside face of the exterior walls, excluding garages, porches and unfinished space (E.4). Above 800 sq ft the zone's lot coverage applies: 30% in RD-1 to RD-4, 50% in RD-5 to RD-15 (Table 2-4). State option: 800 sq ft (§106.42.015.C.1.a(3); Gov. Code §66323(a)(2)). No local standard may block an 800 sq ft unit with 4-ft side and rear setbacks (Gov. Code §66321(b)(3)). · Setbacks: 4 ft for a newly built ADU (§106.42.015.E.1); none for converting, or rebuilding in place, an existing structure (E.1.a). The city's ADU web page and FAQ, written before the 2026 rewrite, still show a 20-ft rear yard for attached ADUs (reducible to 10 ft); the adopted code and Gov. Code §66314(d)(7) cap side and rear setbacks at 4 ft for any new ADU, so ask Planning at (916) 727-4740 before designing to 20 ft. No ADU may sit in an easement without the holder's written consent (E.1.b).

Max size: 1,200 sq ft (CMC 17.85.040(D)). The ADU plus the main house must also stay within the zone's lot-coverage limit, but no standard may block an ADU of at least 800 sq ft and 16 ft in height (17.85.040(E)). An ADU built inside existing space of the house or an accessory building has no size cap. · Setbacks: 4 ft maximum for a new attached or detached ADU, including lot lines along a street (CMC 17.85.040(F)(2)); none for conversions of existing living area or accessory structures, or for a rebuild in the same location and dimensions (F)(1). The city's ADU guide sheet also asks for 5 ft between an ADU and the main house or other accessory buildings.

Max size: 1,200 sq ft of habitable space; ordinance also said the ADU may not exceed the primary dwelling's size — a provision HCD flagged as noncompliant, so confirm with Community Development · Setbacks: 4 ft minimum (3 ft allowed at 12 ft height; 5 ft required for 20 ft height)

Max size: 1,200 sq ft (EGMC 23.90.040(F)(2)); minimum 150 sq ft (23.90.040(E)). A conversion of an existing accessory structure may expand up to 150 sq ft for entry and exit (23.90.040(D)(1)). · Setbacks: 4 ft for new construction (EGMC 23.90.040(G)(2)); none for a conversion of existing living space or an accessory structure, or a rebuild in the same location and dimensions (23.90.040(G)(1)).

Max size: 1,200 sq ft of interior livable space for a Standard ADU (Section 33-1475(d)(2)); a State Exempt detached ADU is capped at 800 sq ft (Section 33-1474(b)(2)). A Standard ADU of 800-1,200 sq ft must meet the zone's front setback and lot coverage; one under 800 sq ft is exempt from both (Section 33-1475(e)(1), (f)). An attached patio cover or similar structure may not exceed 49% of the ADU's area. · Setbacks: 4 ft minimum for detached ADUs and new attached ADUs (Sections 33-1474(b)(1), 33-1475(e)(2)); none for an existing structure converted or rebuilt to the same footprint. Eaves, sills and similar features may project up to 4 ft into a rear setback but no closer than 3 ft to the lot line (Section 33-1475(e)(3)(B)).

Max size: 1,000 sq ft with 2 or more bedrooms, 850 sq ft with 1 bedroom or fewer, measured as interior living space, minimum 150 sq ft (FMC 17.105.150(B)(2)). A new detached unit of 800 sq ft or less with 4-ft setbacks is a '66323 unit' exempt from design review, and no standard may preclude an 800 sq ft ADU (17.105.150(C)(2)). Detached ADUs on two-unit and multi-unit lots are capped at 800 sq ft (17.105.170(B)(2)). · Setbacks: 4 ft minimum (FMC 17.105.150(B)(3)); the city recommends 5 ft to avoid extra Fire Code construction requirements. No setback change for a conversion of an existing house or accessory building, or for an ADU built on top of an existing accessory building that already sits closer than 4 ft.

Max size: 1,200 sq ft for a Class 2 (locally regulated) detached ADU; 800 sq ft for a Class 1 detached ADU, which gets only the state minimum standards (no design review, no parking). On a multifamily lot each detached ADU is capped at 850 sq ft, or 1,000 sq ft with more than one bedroom (ADU Information Sheet, March 2026; Sec. 30-467). · Setbacks: 4 ft minimum for new construction (Sec. 30-467; ADU Information Sheet, March 2026). Conversions of existing structures and their same-footprint rebuilds keep the existing setback (Gov. Code 66314).

Max size: 1,200 sq ft of interior livable space for a new detached ADU (FMC 18.190.005(c)(4)(B)(ii)); garages, carports, covered porches, patios and breezeways are not counted. An ADU converted from existing floor area has no size limit (c)(4)(A). Rooftop decks are prohibited (c)(4)(C). · Setbacks: 4 ft for an ADU built from new floor area (FMC 18.190.005(c)(6)(B)). None for an ADU within existing living area or an existing accessory structure, or one that replaces a structure in the same location and dimensions; up to 150 sq ft may be added for ingress and egress, and any larger expansion is held to the new-construction setbacks and height (c)(6)(A).

Max size: The greater of 1,400 sq ft or 50% of the average floor area of the primary unit(s) (FMC 15-2754.D.4.a). A conversion of an existing accessory structure may expand up to 150 sq ft beyond its footprint for ingress and egress (D.4.a.i). ADUs are excluded from lot-coverage and density calculations (D.1, D.2). · Setbacks: The underlying district's rear setback or 4 ft, whichever is less (FMC 15-2754.D.6.a). 0 ft where the lot abuts an alley, or 2 ft if the ADU's main entrance faces the alley (D.6.a.i). A recorded utility easement must stay clear even if that forces a larger setback (D.6).

Max size: 1,000 sq ft maximum: 850 sq ft with one bedroom, and any ADU over 850 sq ft must have a second bedroom. An ADU of 800 sq ft or less is the state-protected size (4-ft side and rear setbacks, no floor-area-ratio or lot-coverage test); over 800 sq ft the zone's FAR, lot coverage and landscaping standards apply (GMC 30.34.080; city ADU page, Nov. 7, 2025). · Setbacks: 4 ft from interior (side and rear) property lines for an ADU of 800 sq ft or less; no setback for a conversion of an existing permitted structure or a rebuild in the same footprint (GMC 30.34.080; Gov. Code 66323(a)(2)). Larger ADUs follow the zone's setbacks, but state law caps what the city may require at 4 ft for side and rear (Gov. Code 66321).

Max size: 1,200 sq ft of interior livable space for a newly built detached ADU (SFR/MFR checklists, April 2026, item 5/6); no size limit for conversions of existing, permitted structures; state law guarantees at least 850 sq ft (studio/1BR) or 1,000 sq ft (2+BR) (Gov. Code 66321(b)) · Setbacks: 4 ft for a newly built ADU; none for conversions of existing, permitted structures (SFR checklist item 4)

Max size: 1,200 sq ft under state law (Gov. Code 66314(b)(5)); the city cannot apply a lot-coverage, floor-area or open-space rule that would keep out an 800 sq ft detached ADU with 4-ft side and rear setbacks (Gov. Code 66321(b)(2)). The city's free pre-approved plan is a 490 sq ft one-bedroom, one-bath detached unit with an optional 53 sq ft porch · Setbacks: No more than 4 ft for a new detached or attached ADU (Gov. Code 66321(b)(3), 66323(a)(1)); no setback for converting an existing legal structure or rebuilding one in the same footprint and dimensions (Gov. Code 66314(b)(7)). Coastal-zone projects may be held to specific-plan setbacks where they exceed 4 ft (a 2026 downtown project used 5 ft interior and 10 ft street-side)

Max size: 1,200 sq ft (Gov. Code 66314(d)(5)). An 800 sq ft unit with 4-ft side and rear setbacks must be allowed regardless of lot coverage, floor-area ratio or lot size (66321(b)(3)); the city's checklist (Form 67-01, rev. 1/25) states the same 1,200 and 800 sq ft figures · Setbacks: 4 ft (66314(d)(7)); none for a conversion of existing space or a rebuild in the same footprint

Max size: 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 · Setbacks: 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

Max size: 1,200 sq ft under the city ordinance (12.22 A.33(d)(1)), subject to the lot's floor-area (RFA/FAR) and lot-coverage limits; the state-law option (Gov. Code 66323(a)(2)) is 800 sq ft, and no floor-area, lot-coverage, open-space, front-setback or lot-size rule may block an 800 sq ft unit with 4-ft side and rear setbacks (12.22 A.33(c)(1)(iii); Gov. Code 66321(b)(3)). Square footage is measured as Building Code gross floor area inside the exterior walls (ZA Memo 143 Q.3). Conversions of an existing garage or accessory building have no size cap and may add up to 150 sq ft for entry and exit (66323(a)(1)) · Setbacks: 4 ft for a new detached ADU or a new addition (12.22 A.33(c)(8); Gov. Code 66323(a)(2)). None for an ADU created inside an existing house, garage or accessory building, or rebuilt in the same location and dimensions

Max size: 850 sq ft for a studio or one-bedroom unit; 1,000 sq ft for two or more bedrooms, measured as total floor area including all areas within the ADU (Table 17.103.01, Category 2; 7/21/2026 Zoning Criteria Checklist). A Category 1 conversion of an existing detached garage or shed has no size cap other than the existing building envelope plus up to 150 sq ft for an entrance; if enlarged by more than 150 sq ft the whole unit is capped at 850/1,000 sq ft and the addition must meet setbacks (Table notes 3 and 4) · Setbacks: 4 ft from the rear lot line, or the zone's regularly required rear setback if that is smaller, but never less than 3 ft (Table 17.103.01, Category 2). Category 1 conversions and JADUs inside an existing building have no ADU setback, even if the building is nonconforming (note 6). Lot coverage, rear-setback coverage and FAR limits cannot be used to block one JADU plus one ADU of up to 850 sq ft and 18 ft with 4-ft side and rear setbacks

Max size: 1,200 sq ft under the state standard Oceanside now applies (Gov. Code 66314(d)(5)). A unit of at least 850 sq ft (studio/1BR) or 1,000 sq ft (2+ BR) cannot be blocked by lot coverage, floor-area ratio or open-space rules (66321(b)(2)-(3)), and an 800 sq ft detached ADU with 4-ft side and rear setbacks is approved by right regardless of other standards (66323(a)(2)). · Setbacks: 4 ft is the most the city may require for new construction; none for a conversion of an existing structure or a rebuild in the same footprint (Gov. Code 66314(d)(7)). Coastal Zone: the certified LCP's habitat buffers and coastal-bluff geologic setbacks still apply to garage conversions and units built above garages (Coastal Commission certification LCP-6-OCN-18-0055-1, Sept 2018).

Max size: 1,000 sq ft of interior livable space for 2 or more bedrooms; 850 sq ft for a studio or 1-bedroom (Dev. Code 5.03.010.F.1.a). Lot coverage (30-60% by zone) can shrink it, but never below 800 sq ft (F.1.c). A state-standard Class 1 detached unit of 800 sq ft or smaller with 4 ft side/rear setbacks is approved without Ontario's design, landscape or front-setback rules (D.3.a(2)). · Setbacks: 4 ft minimum (Dev. Code 5.03.010.F.2.a); no setback for a conversion or for a unit rebuilt in the same location and dimensions as an existing structure (F.2.b). Detached structures must be 6 ft apart (ADU Handout, Rev. 01.21.2025).

Max size: 1,200 sq ft for a new detached ADU on a single-family lot (17.50.275.D.1.a). Hillside Overlay lots outside HD-1: 1,000 sq ft, or 800 sq ft where the street pavement is 26 ft wide or narrower (D.1.b). Conversions of existing space have no size limit. Floor area may be measured by the Zoning Code or the California Building Code, whichever the applicant prefers (D.1.d). · Setbacks: 4 ft for new construction and for any addition to a conversion ADU. No setback beyond fire-safety needs for a conversion of existing space or for a rebuild in the same location, dimensions and height (17.50.275.D.3.a).

Max size: 850 sq ft for a studio or one-bedroom; 1,000 sq ft with two or more bedrooms (city ADU standards table, RCMC 23.901.060). Those are exactly the floors a city must allow under Gov. Code 66321(b)(2): the published cap is the state minimum, the city publishes no higher figure (such as 1,200 sq ft), and the codified text could not be read. Lot coverage cannot block an 800 sq ft unit with 4 ft side and rear setbacks (66321(b)(3)); a detached unit under the 66323 route is capped at 800 sq ft. · Setbacks: 4 ft (city ADU standards table), the most state law allows for a newly built ADU (Gov. Code 66314(d)(7)). No setback may be required for an existing structure converted to an ADU, or for a new structure rebuilt in the same location and to the same dimensions. The city notes its setbacks are general standards that may vary with existing easements.

Max size: 1,200 sq ft maximum, 350 sq ft minimum (Handbook p. 7; RCMC 17.100.050). Lot-coverage limits may cap a detached unit, but never below 800 sq ft at 16 ft height with 4 ft side and rear setbacks (Gov. Code 66321). · Setbacks: 4 ft minimum from the rear lot line for new construction, detached or attached; converting an existing garage or accessory structure keeps its existing setbacks (Handbook pp. 7-9; RCMC 17.100.050).

Max size: 1,200 sq ft of floor area (RMC 19.442.030(D)(2)). A movable ADU (MADU, a unit on a chassis) must be 150-430 sq ft measured to the outside of the exterior walls (D)(3). Any ADU must be at least the size of an efficiency dwelling unit under California Building Code 1208.4 (D)(5). ADU floor area is not counted toward lot coverage (A)(8) · Setbacks: 4 ft for a new one-story ADU or MADU up to 16 ft tall, measured from the rear lot line and from other buildings; a taller or two-story new ADU, or a new second story added to an existing structure, must meet the base zone's rear setback (RMC 19.442.030(C); city ADU FAQ). No added setback for converting an existing structure or an existing second story. State law caps side and rear setbacks at 4 ft for any new ADU (Gov. Code 66314(d)(7)) and guarantees a detached ADU of at least 800 sq ft with 4-ft setbacks at 16 ft (18 ft near major transit), so ask the Planning Division before assuming a larger setback applies to a taller unit

Max size: 850 sq ft (studio/1BR) or 1,000 sq ft (2+BR) per city handout — the state floor; minimum 150 sq ft · Setbacks: 4 ft for new construction; none for conversions of existing structures (including same-footprint rebuilds)

Max size: Local option: 1,200 sq ft for one detached ADU; with two detached ADUs their combined floor area may not exceed 1,200 sq ft, for example 400 + 800 (17.228.105(B)(2)(b)(iii)). Floor area counts everything inside the ADU's building envelope except garages and accessory structures. State option: 800 sq ft for a new detached unit (17.228.105(C)(1)(b)) · Setbacks: 3 ft or none under the local option: no rear setback is required for a single-story ADU, or the first floor of a two-story ADU, when the whole unit is more than 60 ft from the front property line; if any part is within 60 ft of the front property line, or for a second floor, the zone's rear setback or 3 ft applies, whichever is less, so 3 ft in R-1 and R-2 (17.228.105(B)(2)(c)(iii)). No setback for an existing structure converted or rebuilt to the same footprint. No ADU may sit inside the 20-ft setback from the landside toe of a levee (17.204.240(E)). State option: 4 ft (17.228.105(C))

Max size: 1,000 sq ft of interior livable space for a unit with two or more bedrooms and 850 sq ft for a studio or one-bedroom under the city's Class 2 standards (19.04.030(2)(P)(7)(a), Ordinance MC-1659); a Class 1 detached ADU under state law is 800 sq ft of livable space or less (5.a.ii). No lot-coverage, FAR, front-setback or open-space rule may force any ADU below 800 sq ft (7.a.iii). Minimum interior width 10 ft in every direction with a 7-ft ceiling (7.h.v) · Setbacks: 4 ft (19.04.030(2)(P)(5)(a)(ii) for a Class 1 detached ADU; 7.c.i for a Class 2 ADU). No setback beyond fire-code separation for a conversion inside existing space, and none when the ADU is built in the same location and to the same dimensions as an existing structure (7.c.ii)

Max size: 1,200 sq ft gross floor area (minimum 150 sq ft) for a new attached or detached ADU (SDMC 141.0302(b)(7)). ADU floor area counts toward the lot's floor area ratio, but one ADU of 800 sq ft or less is always allowed and is exempt from FAR, lot coverage, front setback and open-space rules (141.0302(b)(4)). Garage or carport space under an ADU and an exterior-access mechanical closet do not count toward the 1,200 sq ft (DSD FAQ) · Setbacks: None for an ADU 16 ft or lower outside a High or Very High Fire Hazard Severity Zone; the Building Code's fire-separation rules may still push the wall off the line. Over 16 ft next to a residential lot: 4 ft or the zone's rear setback, whichever is less. In a High or Very High Fire Hazard Severity Zone: 4 ft at any height (141.0302(b)(9)(C)-(D)). Conversions and same-footprint rebuilds keep the existing structure's setbacks (141.0302(a)(5))

Max size: State program: 850 sq ft of gross floor area for a studio or 1-bedroom detached ADU and 1,000 sq ft for 2 or more bedrooms on a lot with a single-family home (Planning Code 207.2(c)(1) and (d)(5)(B); Ordinance 222-25 raised the streamlined cap above the 800 sq ft state floor, effective December 22, 2025). A detached ADU on a lot with an existing multifamily building has no maximum size (Planning Director Bulletin No. 3, June 2026). Local program: the same 850 / 1,000 sq ft caps for the one detached rear-yard ADU (207.1(c)(15)(B)). San Francisco measures gross floor area, not interior livable space · Setbacks: State program: 4 ft from the rear lot line for a new detached or attached ADU; no setback for an ADU within existing living space or an existing accessory structure, or one that replaces an existing structure in the same location and dimensions; for an ADU that is part of new construction the 4 ft applies only to the part outside the buildable area (Planning Code 207.2(d)(7)). Local program: 4 ft for the detached rear-yard ADU (207.1(c)(15)(A)); none for a conversion of existing space; otherwise the district rear yard applies, which is 30% of lot depth in RH, RM-1, RM-2 and RTO districts and 25% in other residential districts (Planning Code 134; ZA Bulletin 5, Sept. 2025), unless the Zoning Administrator waives it for an ADU in an existing building (207.1(g))

Max size: Two tracks that cannot be mixed. City standards (SJMC 20.80.175 D.1, Table 20-55): 1,000 sq ft on lots up to 9,000 sq ft, 1,200 sq ft on larger lots, and no cap when converting an existing detached accessory structure. State standards (SJMC 20.80.176 / Gov. Code 66323): 800 sq ft. Minimum 150 sq ft on either track. Square footage is livable floor space measured to the exterior finish; a covered porch or balcony more than 50% enclosed counts (20.80.175 E.3). · Setbacks: City standards: 0 ft for a one-story detached ADU; 4 ft, with eaves of 1 ft or less, for any second story (SJMC 20.80.175 D.3). State standards: 4 ft. A structure converted to an ADU keeps its existing setback; Building and Fire Code separations and easements still apply. City-track detached units must sit at least 6 ft from the main home and, with other accessory structures, cover no more than 40% of the rear yard, a cap that cannot block an 800 sq ft ADU with 4 ft setbacks (D.5.c, D.5.e).

Max size: No fixed cap: up to the FAR of the underlying zone and no larger than the primary home. The first 800 sq ft of ADU living area is exempt from FAR, and an 800 sq ft state-exempt ADU is always allowed even when the lot's floor area is used up or the main house is under 800 sq ft (SMMC 27.19.060(b)) · Setbacks: 4 ft for new construction; none for a conversion rebuilt to the same footprint and height, or for a detached ADU in the rear third of the lot that meets the R1 accessory-structure rules in SMMC 27.70 (27.19.060(d))

Max size: 1,000 sq ft (Table 41-194.3); minimum 220 sq ft. Capped at 800 sq ft when both an ADU and a JADU are built on the same lot (41-194.3(B)). Converting an existing accessory structure or part of the house has no size limit and the structure may be expanded up to 150 sq ft (41-194.3(C)-(D)). An ADU over 800 sq ft must also leave 1,200 sq ft of continuous rear or side open space and sit 15 ft from the main house (41-194.3(I)-(K)) · Setbacks: 4 ft (Table 41-194.3). No setback for a conversion of an existing structure, or for an ADU rebuilt in the same location and to the same dimensions as a demolished structure that already encroached (41-194.3(F)-(G)); an ADU built above an existing garage that encroaches into a required yard must keep 4 ft

Max size: 850 sq ft (studio/1-bedroom) or 1,200 sq ft (2+ bedrooms) under the local standards, 150 sq ft minimum; a garage with an internal connection to the ADU does not count toward the cap (SMMC 9.31.025(I)(1)(c)). The state-mandated alternative under 9.31.025(J) is 800 sq ft · Setbacks: 4 ft (SMMC 9.31.025(I)); no setback for existing space or a structure rebuilt in the same location and to the same dimensions, including unpermitted structures built before Jan 1, 2020 that are converted to an ADU (Guide p.3)

Max size: 1,000 sq ft (800 sq ft under the state-exempt ministerial path); accessory-structure conversions exempt from the cap · Setbacks: 4 ft (detached); same as primary dwelling for attached; none for conversions of existing structures

Max size: Building permit only: one detached new ADU of 800 sq ft or less (§ 17.37.040(A)(2)). ADU permit: 850 sq ft for a studio/1-bedroom, 1,000 sq ft for 2+ bedrooms (§ 17.37.060(A)); no lot-coverage, FAR, front-setback or open-space rule may push the ADU below 800 sq ft. · Setbacks: 4 ft minimum (§ 17.37.060(B)); none when the ADU is built in the same location and to the same dimensions as an existing structure

Max size: 800 sq ft of floor area (BRC 9-6-3(n), Table 6-3); 1,000 sq ft for an affordable ADU (rent capped at 75% of area median income under a recorded declaration of use) or on a designated historic property. Floor area is measured to the outside of the exterior walls per Ch. 9-16 and includes stairways; space under a 6 ft ceiling is excluded. · Setbacks: Detached ADU (an accessory building) in RL-1, RL-2, RM-1, RM-2, RMX-1, RE and RR: 0 or 3 ft from the rear lot line (Table 7-1; a 0 ft setback needs a maintenance easement recorded with the neighbor unless the lot backs an alley or street), and 6 ft from any other building. Attached ADU: the principal rear setback can drop to 5 ft where only ADU floor area sits in the setback, that part is no taller than 20 ft and, in RR/RE/RL/RMX-1, covers no more than 500 sq ft (9-6-3(n)(2)(B), Ord. 8650).

Max size: 50% of the principal dwelling's floor area or 1,250 sq ft, whichever is less; if the principal dwelling is under 1,500 sq ft the ADU may be 750 sq ft. ADU floor area does not count toward the lot's accessory-structure floor-area cap (7.3.304.E.2.a). · Setbacks: 5 ft for a detached ADU. The code caps the rear setback at the lesser of the district's accessory-building rear setback or 5 ft, so the City cannot require more (7.3.304.E.2.c(2)).

Max size: SU districts: ADU gross floor area 864 sq ft on lots of 7,000 sq ft or less, 1,000 sq ft on larger lots (DZC 11.8.2.1.B.2); the detached ADU building footprint is capped at the same 864/1,000 sq ft (e.g., DZC 5.3.4.5.A). Other districts: 1,000 sq ft footprint per unit, GFA not separately capped. · Setbacks: U- districts: 5 ft, or 0 ft where an alley abuts the rear line and no garage door faces it. E-SU: 5 ft where an alley or street abuts the rear; otherwise 5 ft (1-story) or 12 ft (2-story). S-SU: 10 ft (1-story) or 20 ft (2-story). The detached ADU must sit in the rear 35% of lot depth (U-, E-) or rear 50% (S-) (DADU building form tables).

Max size: Accessory-building footprint: the greater of 650 sq ft or 30% of the required rear yard in R-1/R-2, 550 sq ft in R-3 and the RF zones (D §5003, E §5003; raised from 450 sq ft on 7/10/2026). It counts toward the 40% lot occupancy (60% for an R-3 row house, D §210.1), may hold one dwelling unit and no roof deck (U §253.8(e)). · Setbacks: Accessory building: at least 7.5 ft from the centerline of any alley, 3 ft from a rear lot line that does not abut an alley or street, and no more than 30% of the required rear yard may be occupied by accessory buildings (D §5004.1, as amended 7/10/2026). The house itself needs a 25 ft rear yard in R-1 and 20 ft in R-2/R-3 (D §207.1).

Max size: Building footprint capped at the lesser of 25% of the principal house's gross floor area or 750 sq ft (Sec. 656.403(g)(3)): a 2,000 sq ft house allows a 500 sq ft footprint, a 3,000 sq ft house the full 750 sq ft. The cap is on footprint, not floor area, and the unit must be behind the house and outside all required yards ((g)(1), (g)(4)). · Setbacks: The ADU may not stand in any required yard (Sec. 656.403(g)(4) and (a)(2)), so it must meet the house's district rear setback: 10 ft in every RLD district, RLD-120 through RLD-TND (Sec. 656.305(f)). RMD and PUD lots: confirm the figure with the Zoning Section (904-255-8300).

Max size: 10% of lot area, up to 800 sq ft; the cap cannot be Waived (Art. 6 Table 13). Minimum sizes: 275 sq ft efficiency, 450 sq ft one-bedroom, 550 sq ft two-bedroom. A 5,000 sq ft lot therefore allows 500 sq ft; you need an 8,000 sq ft lot to reach 800 sq ft. · Setbacks: 5 ft for a detached or one-story ancillary building (Illustration 5.3, Ancillary Building Setback). A two-story ADU attached to the house follows the principal rear setback of 20 ft (Sec. 3.18).

Max size: 500 sq ft on a lot meeting the base minimum, or 1,000 sq ft on a larger lot in the R-1 districts (Sec. 58.501(C)); no code minimum size. House plus ADU floor area is capped at 0.50 FAR (0.40 in Colonialtown R-2A/T/SP), the ADU must be smaller than the house, and it may cover at most 35% of the backyard. Historic districts: 700 sq ft max by Certificate of Appropriateness. Lake Nona PD: 1,000 sq ft on any lot. · Setbacks: Detached: 5 ft if the ADU is 12 ft tall or less (one story), 15 ft if taller (Sec. 58.901(c)); 5 ft separation from the house, 10 ft if over 12 ft tall. Attached: same as the house, 25 ft in R-1A, R-1, R-2A and R-2B (Ch. 58 Part 1B). A two-story ADU under 500 sq ft may ask for a rear-setback Modification of Standards (Sec. 65.302).

Max size: 950 sq ft of living space (Sec. 27-132); 1,100 sq ft in the Tampa Heights Overlay (Sec. 27-244). An ADU larger than 15% of the lot area must sit 20 ft from the rear line and 7 ft from the side line instead of 3 ft · Setbacks: 3 ft; 20 ft if the ADU exceeds 15% of the lot area

Max size: 750 sq ft or less (definition, Sec. 16-29.001(12)(a)7). Two further caps apply to any accessory building in R-1 through R-5 (Sec. 16-28.004(3)): gross floor area no more than 30% of the main house's floor area, counting garage and unconditioned space in the ADU, and footprint no more than 25% of the rear yard. A 2,000 sq ft house therefore allows a 600 sq ft ADU, not 750. · Setbacks: R-5: 4 ft (Sec. 16-07.008(3), ADU exception). R-4 and R-4A: 15 ft, the district rear yard with no ADU exception (Sec. 16-06.008(3), 16-06A.008(3)); a Board of Zoning Adjustment variance ($100 filing fee) is the only way to go closer.

Max size: Footprint capped at 40% of the principal dwelling's footprint, not to exceed 700 sq ft; in A-1, RSF-E, RSF-30 and RSF-20 the cap is 40% or 1,000 sq ft, whichever is less (Sec. 8.7.4.d). Footprint is measured at finished grade inside the exterior walls (Sec. 13.3), so second-storey floor area is not capped. No minimum floor area since May 2023: the unit must meet the building code (2018 IRC). Maximum one bedroom; variable through the Zoning Board of Appeals ($620). · Setbacks: Detached ADU: 5 ft; 3 ft where the lot abuts a lane; none where the district sets no rear setback for the principal building (Sec. 8.7.4.a.iii). Portions over 15 ft tall need 15 ft from a rear line without a lane. An attached ADU uses the principal dwelling's rear setback (RSF-6 and RSF-5: 20 ft).

Max size: 1,000 sq ft of floor area on zoning lots of 5,000 sq ft or more; 500 sq ft on lots up to 4,999 sq ft (ROH § 21-5.50-3(a)(1)(B), Ordinance 25-2, effective September 30, 2025). A legally built accessory structure that predates September 14, 2015 may be converted and exceed the cap by zoning adjustment if the director finds the floor area cannot practicably be reduced (§ 21-2.140-1(n)) · Setbacks: 5 ft in R-3.5 through R-20 for a single-unit, two-unit or duplex dwelling and the ADU that shares its lot (Table 21-3.2); 8 ft in R-3.5 and 11 ft in R-5 to R-20 when the lot's floor area ratio exceeds 0.6 (§ 21-3.70-1(c)(3)(H)); 10 ft in the Country district (Table 21-3.1)

Max size: any size that fits the coach house bulk rules; Chicago sets no floor-area cap since the pilot's seven-hundred-square-foot dwelling-unit limit was repealed with the citywide ordinance (effective April 1; see recent changes). What sizes the building: 22 ft height limit, one dwelling unit per coach house, a 15 ft gap behind the main house, the rule that all accessory buildings together may cover no more than 60% of the required rear setback area, and a 3 ft open strip along one side. Coach houses are exempt from floor-area-ratio, lot-area-per-unit and rear-yard open-space minimums but may not eat into open space the main building needs · Setbacks: 2 ft from the rear lot line where the lot backs onto a public alley, waived if the coach house is at least 10 ft from the alley centerline as shown on a survey (17-17-0309). A coach house is one of the few structures allowed inside the required rear setback, but all accessory buildings together may occupy no more than 60% of that setback area (17-9-0201-D). A minimum 15 ft separation is required between the rear wall of the main house and the front wall of the coach house; on lots less than 125 ft deep the Zoning Administrator can cut it to 10 ft by administrative adjustment (17-9-0201-F(8), 17-13-1003-PP)

Max size: 1,000 sq ft · Setbacks: 12 feet

Max size: By right only in Mattapan R1/R2: building floor plate up to 900 sq ft or the floor plate of the main house, whichever is less (Article 60). Elsewhere the code has no detached-ADU rule, so any size needs a ZBA variance. · Setbacks: 20 ft in Mattapan R1/R2 for a lot adding an ADU (Article 60 dimensional table for ADU lots). Elsewhere the base subdistrict's rear yard applies and a detached ADU needs a ZBA variance.

Max size: No local size cap since Feb 10, 2025 (Ord. 2025-1 struck the 900 sq ft / 35% rule in old 4.22.1). To keep state Protected Use status the unit must be 900 sq ft or 50% of the principal dwelling's gross floor area, whichever is less; a larger unit is simply an additional dwelling unit, which Cambridge also allows as of right with no FAR limit for residences (5.25.4(a)) and no lot-area-per-unit rule. · Setbacks: 5 ft in Residence C-1 for residential buildings (Table 5-1, col. 5); an accessory building may not sit closer to any lot line than the district minimum (4.21(h)). No setback where the building abuts a neighbor's building across a party wall (5.40 fn. 4(a)). Eaves, bay windows and similar projections of up to 3.5 ft may extend into the yard (5.24.1(f)).

Max size: The smaller of 900 sq ft or half the principal dwelling's gross floor area. Medford § 94-8.2.3(4) and M.G.L. c. 40A § 1A / 760 CMR 71.02 agree on the number. Under 760 CMR 71.02, GFA counts every story of compliant ceiling height including basements and lofts but excludes crawl spaces, garages, attics and enclosed porches — so a 1,400 sq ft house gets a 700 sq ft unit. § 94-8.2.3(4) lets the Board exceed 900 sq ft only for a carriage house or barn with preservation value, by special permit. · Setbacks: 3 ft for a detached ADU, or 1 ft with fire-resistance-rated wall assemblies (§ 94-4.3.2(3), accessory structures). A dwelling needs a 15 ft rear yard (Table B, row 1), but 760 CMR 71.03(3)(b)(2) gives the ADU the more permissive of the two. An accessory building may occupy up to 25 percent of the rear yard (§ 94-4.2.5(1)) and must sit at least 10 ft from the house and from any other accessory building (§ 94-4.1.2(3)(a)).

Max size: 1,000 sq ft or 50% of the combined gross floor area of house plus ADU, whichever is less, by right (Sec. 6.7.1.E.2); 1,001-1,200 sq ft by right if the unit is in an accessory building with a final permit sign-off at least 4 years old (E.2.c) or the owner lives in the house or ADU and files an annual certification (E.2.d); up to 1,500 sq ft by City Council special permit (E.2.b). These caps are local; the state Protected Use size is 900 sq ft or half the main house. · Setbacks: 5 ft for a detached ADU of no more than 1.5 stories and 22 ft (accessory-building setback, Sec. 3.4.3 via Sec. 6.7.1.E.4; Planning FAQ); a taller unit meets the single-family rear setback for the district (ISD Zoning Chart: 40 ft SR1, 30 ft SR2/SR3, 15-30 ft MR on post-1953 lots; 25 ft on older SR lots). The 1.5-story setback can be reduced by special permit (E.4).

Max size: 900 sq ft or 50% of the principal dwelling's gross floor area, whichever is less (760 CMR 71.02, applied by the ISD guideline). Minimum 320 sq ft for a detached ADU — a local ISD figure, not a state or 780 CMR rule. Example: a 1,500 sq ft house allows 750 sq ft; 1,800 sq ft or larger allows the full 900. · Setbacks: Detached ADU must meet the principal-building yards in QZO Table 4.1 (ISD guideline): Residence A 20 ft rear; Residence B (1-3 units) 25 ft rear; Residence C half the building height, never less than 25 ft. Note: a garage or shed may sit 6 ft from the rear line (§375-3.2.3.1) and 760 CMR 71.03(3)(b)2 bars ADU dimensional rules stricter than those for an accessory structure — ask ISD in writing which figure it will apply.

Max size: Local Backyard Cottage: 576 sq ft floor plate, max 24 ft wide x 32 ft deep, 1.5 stories (SZO §3.1.12.c). State Protected Use ADU: up to 900 sq ft or 50% of the principal dwelling's gross floor area, whichever is smaller (760 CMR 71.02); a detached state ADU may be built to that cap, and city dimensional rules can be no stricter than those for the house or an accessory structure (71.03(3)(b)2). The pending Sept 2026 amendment would swap the 576 sq ft floor plate for a 1,750 sq ft GFA cap. · Setbacks: 3 ft minimum; 3 or 20 ft where the lot abuts an alley (SZO §3.1.12.b). 10 ft minimum separation between the cottage and the principal building.

Max size: 450 to 900 sq ft: 'The minimum floor area of an ADU shall not be less than 450-square feet. The maximum floor area of an ADU shall not exceed 900-square feet, or 50% of the total gross floor area of the principal dwelling unit, whichever is smaller' (§ 3.23(b), Ord. No. 36552). Under 1,800 sq ft of house the half rule binds first; gross floor area follows 760 CMR 71.02. The 450 sq ft floor is Waltham's own; 760 CMR 71.02 allows 'additional size restrictions' subject to the 71.03(3)(a) test. · Setbacks: 5 ft from the rear lot line is the operative figure for a protected-use ADU: the accessory-building standard is 5 ft from rear and side lines and 10 ft from the house (§ 4.221), and 760 CMR 71.03(3)(b)(2) bars any ADU setback stricter than the principal-dwelling or accessory-structure standard, 'whichever results in more permissive regulation'. On its face § 3.23(c) applies the district rear yard — 40 ft in RA-1/RA-2, 30 ft in RA-3/RA-4/RB, 20 ft in RC/HR1, 60 ft in RD (Table 4.11). The 10-ft separation and 25%-of-rear-yard cap still apply.

Max size: 900 sq ft gross floor area (Section 8(G)(5)(a)); larger by Planning Board special permit (Section 8(G)(7)). GFA counts every story of code-compliant ceiling height, including basements and lofts, measured from the interior face of exterior walls, and excludes crawl spaces, garage parking, attics and enclosed porches (Section 8(G)(2)). Worcester applies no 50%-of-principal-dwelling test, so the local 900 sq ft cap is more permissive than the state Protected Use ADU definition. · Setbacks: 5 ft, via the accessory-structure standard in Section 8B(10) (no accessory building closer than 5 ft to any lot line), which Section 8(G)(5)(b)i lets an ADU use because it is more permissive than the Table 4.2 principal-building rear yard (20 ft in RS-10, RS-7 and RL-7; 15 ft in RG-5). Setbacks that cannot be met may be modified by Planning Board special permit (Section 8(G)(7)).

Max size: 600 sq ft on lots up to 7,199 sq ft; 800 sq ft on lots 7,200 sq ft or larger — or the ground-floor area of the main dwelling, whichever is less · Setbacks: Allowed in the rear setback area if at least 3 ft from any lot line and all structures cover no more than 35% of the rear setback area; fire-rated walls required if 3-5 ft from a lot line

Max size: No ADU size rule exists because no ADU use exists. The lapsed proposal (draft Sec. 50-12-466(1)e) would have capped an ADU at the smaller of 1,200 sq ft or 60% of the principal dwelling's gross floor area. Today a building accessory to a one- or two-family house is limited to one story and 15 ft (Sec. 50-13-209). · Setbacks: Garages and other accessory structures: 3 ft from the rear lot line, or up to the lot line where an alley gives vehicle access (Sec. 50-13-226 encroachment table). The lapsed proposal kept 3 ft and would have waived the rear setback for ADUs on lots that abut an alley (draft Sec. 50-13-212(4)).

Max size: 1,000 sq ft gross floor area maximum, and the ADU may never be larger than the primary house (Sec. 5.9.03 as amended June 2026; replaced the 850 sq ft / 40%-of-house cap). Gross floor area is measured from the exterior faces of the structure. Minimum greenspace (LDR 40-60%, MDR 30-50% depending on neighborhood classification) counts all buildings, pavement, decks and patios and can limit the footprint further · Setbacks: Detached ADU: accessory-structure setback of 3 ft from the rear lot line (Sec. 5.9.03(E)(2); June 2, 2026 city briefing). Attached ADU: the primary-structure rear setback of its zone district (25 ft in the Traditional Neighborhood classification). An Administrative Departure ($260) can allow a detached unit as close as 1 ft where site constraints justify it

Max size: 1,300 sq ft gross floor area on all levels (garage space counts) or 16% of lot area, whichever is greater; never more than 1,600 sq ft or larger than the main house. Separately, the combined footprint of the ADU, every other detached accessory building and any attached garage is capped at 800 sq ft or 10% of lot area, whichever is greater (550.1460(2)-(3)). · Setbacks: Detached: may be reduced to 3 ft, except no reduction on a side where vehicle-access doors face the rear lot line, and at least 5 ft from a rear lot line that coincides with the side lot line of a lot in an urban neighborhood or residential mixed-use district (550.1460(5)-(6)). Internal/attached: the district's rear-yard setback applies.

Max size: 800 sq ft or 75% of the floor area of the principal dwelling, whichever is greater (Sec. 65.913(d)). Floor area is measured from the interior faces of the exterior walls (Sec. 60.207); DSI asks for the main house's floor plans with the permit to check the 75%. All buildings together must also stay under the district lot-coverage cap: 40% RL, 45% H1, 50% H2 (Table 66.231). · Setbacks: Detached ADU: may sit in the required rear yard; 1 ft minimum from an alley right-of-way, otherwise 3 ft from the rear (interior) lot line (Sec. 63.501(b)). The 3 ft interior-line setback is waived with a recorded maintenance easement if the building stays 3 ft from any building next door. Attached ADU: the house's rear setback, 10 ft in RL, H1 and H2 (Table 66.231).

Max size: 800 sq ft floor area or 90% of the house's floor area, whichever is smaller (88-305-15-C.7.d). Footprint also capped at 60% of the house's footprint or 25% of the rear yard, whichever is smaller, and never more than 800 sq ft (C.7.c). An ADU in or on a garage counts the garage's floor area cumulatively (C.4), and all detached accessory buildings together must stay within 88-305-02-E (C.7.f). · Setbacks: 5 ft from all property lines, measured to projections such as eaves (88-305-15-C.7.b). Any other setbacks follow the accessory-structure rules of 88-305-02 (C.7.e).

Max size: 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. · Setbacks: 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).

Max size: 50% of the principal dwelling's floor area. A detached ADU must meet the district's accessory-structure standards (LVMC 19.06.040(C)(8)): in R-1, R-SL, R-CL, R-TH, R-2, R-3, R-4 and R-MH the Table 2/3 accessory size limit is "not to exceed 50% of the floor area of the principal dwelling unit", and U, R-E and R-D carry the same 50% rule as an ADU footnote to their tables. All accessory buildings together may also cover no more than 50% of the rear yard, and total lot coverage stays within the district cap (50% in R-1). The separate 19.12.070 ceiling - no larger than the home's gross floor area - applies on top, so a detached casita is always the smaller of the two · Setbacks: 3 ft minimum for a detached ADU in R-1, R-SL, R-CL, R-TH, R-D, R-2, R-3, R-4 and R-MH (Table 2, Accessory Structures); 5 ft in U and R-E. No setback is required from a property line that abuts an alley (LVMC 19.06.040(C)(3)). An attached ADU uses the house's rear setback instead (15 ft in R-1)

Max size: 800 sq ft or 50% of the principal dwelling's gross floor area, whichever is less, with a 200 sq ft minimum; a tiny-house ADU may not exceed 400 sq ft (§17.20.030.F.2.c.iv). A no-kitchen guest house/casita is capped at the lesser of 25% of the house's living area or 800 sq ft on a 6,000 sq ft lot (§17.20.030.D.2.a.iii). Other accessory buildings: 600 sq ft, or 1,200 sq ft on a 15,000 sq ft lot; all accessory buildings together may cover at most 25% of the rear yard (§17.20.030.D.2.a–b). · Setbacks: 3 ft for an accessory structure in every residential district — O-L, R-E, R-EL, R-1, R-CL, R-2, R-3 and R-4 (Table 17.24.010-2). The principal dwelling in R-1 must keep 15 ft, so the accessory allowance is a real gain. The binding limit is usually coverage: all accessory buildings, detached garages and casitas together may not occupy more than 25% of the rear yard (§17.20.030.D.2.a–b).

Max size: No square-footage cap in the ordinance or the city's homeowner guide ('There is no limit on square footage of an ADU'). Size is set by the 18 ft/2-story accessory height limit, the 2-3 ft side setbacks and the lot-coverage cap: R-1 lot coverage rises by 5% when an ADU is present (§345-41 E.12.c), i.e. 90% on lots up to 1,800 sq ft, 80% on 1,800-3,200 sq ft, 90% on 3,200 sq ft or more; R-2 80% (§345-42 E.11); RH-1 75% lot / 55% building coverage (§345-40 E.9-10); RH-2 75% (§345-40.1 E.10). · Setbacks: R-1: no zoning rear setback for accessory buildings ('No standard', §345-41 E.12.b) — the city's guide notes 2 ft applies per the building code; R-2: 3 ft (§345-42 E.16.b); RH-1: 0 ft (§345-40 E.12.a); RH-2: no standard (§345-40.1 E.13.b). Separation from the main house is governed by fire, health and safety codes (§345-60 I.1.c; 2021 IBC New Jersey Edition).

Max size: Living area no more than 40% of the primary dwelling unit, minimum 300 sq ft, maximum 800 sq ft, no more than three rooms excluding kitchen and bathroom (§347-8 D(3)); a fully accessible adaptive-reuse ADU may add 5% (D(8)). Detached ADUs also follow §347-22: rear yard only, at most 25% of the rear yard (15% in R-O/R-O(a)), footprint up to 24 ft in any direction (36 ft in R-O/R-O(a)); Ord. O-25-29 (Aug 2025) changed the ADU dimension rule - confirm the current figure with the Zoning Officer. · Setbacks: Detached ADU in R-1: 6 ft minimum rear yard setback for accessory structures (§347-46 A(3)); R-O: 10 ft (§347-34 A(3)). R-O(a) and R-2 accessory-structure setbacks: confirm with the Zoning Officer. An accessory structure within 4 ft of the house counts as part of it and must meet principal-building setbacks (§347-22 E).

Max size: 800 sq ft or 25% of the principal dwelling's total floor area, whichever is greater (§T10B-255(c)(3)c); a detached ADU building may not exceed the size of the main house ((c)(3)d, Ord. 2022-14). Deed-restricted low/moderate-income (UHAC) ADU: 1,000 sq ft or 30%, whichever is greater. A fully barrier-free unit earns the property a 5% floor-area bonus usable on the house, the ADU or both. Maximum 3 habitable rooms (4 if affordable). · Setbacks: Detached ADU follows the accessory-structure setbacks of §T10B-256.2(b)(1): 3 ft if the building is 100 sq ft or less, one story and 10 ft tall; 5 ft if up to 1.5 stories and 20 ft; the district's principal-building setback if up to 2 stories and 25 ft. It may never be closer than 5 ft to the habitable part of the main house (§T10B-255(c)(3)l). Former Borough districts: confirm the accessory-building setback with the Zoning Office.

Max size: 800 sq ft gross floor area (§ 315-9.4B.7), and in no case more than 40% of the primary dwelling's floor area or 2 bedrooms (§ 315-9.4B.8). GFA is measured to the exterior faces of the exterior walls (§ 315-2.4F). The footprint of a detached accessory structure also cannot exceed the footprint of the principal building (§ 315-9.4A.5). · Setbacks: 10 ft from the rear lot line for a detached ADU (§ 315-9.4B.6). Setbacks for roofed structures are measured from the edge of the roofline, eaves included (§ 315-9.4A.3.d).

Max size: 750 sq ft of gross floor area (IDO 14-16-4-3(F)(6)(a)); an attached garage does not count toward the cap. All accessory buildings together may also cover no more than 25% of the combined side and rear yards (14-16-5-11(C)(4)(a)). Downtown Neighborhood Area CPO-3: 650 sq ft (4-3(F)(6)(g)1). · Setbacks: 5 ft minimum from either the rear or one side lot line (14-16-4-3(F)(6)(b)); other accessory-building lot lines carry no zoning setback (14-16-5-11(C)(4)(d)). Separately, the building code needs 5 ft between buildings unless the casita is fire-rated.

Max size: 1,000 sq ft gross floor area max; a detached ancillary dwelling must also be lower in height (feet) and smaller in footprint than the principal building, and must meet the Sec. 3.2.3 carriage-house standards (UDO Sec. 6.1.2.B). · Setbacks: 0 ft base for an ancillary carriage house; if it encroaches on the main house's required rear yard it must be at least 18 in from the lot line (no setback along an alley) and all accessory structures together may not cover more than 50% of that yard (UDO Sec. 3.2.3.D).

Max size: 800 sq ft of zoning floor area (ZR 12-10), which counts toward the lot's floor area ratio; a backyard ADU may also cover no more than one-third of the required rear yard (ZR 23-341(b)(4)), so a 500 sq ft footprint needs a 1,500 sq ft rear yard. Converting a garage or shed that existed before Dec 5, 2024 is not a 'backyard ADU' and is allowed even where new ones are barred. · Setbacks: A free-standing backyard ADU may stand inside the required rear yard as a permitted obstruction but must be at least 5 ft from the rear lot line and cover no more than one-third of the rear yard (ZR 23-341(b)(4)). A converted pre-Dec 2024 garage may keep its existing non-complying position (DOB ADU Types page).

Max size: Not applicable today. Proposed (ZAP final draft Sec. 3.7.A.7): 800 sq ft maximum, not exceeding the gross floor area of the main house; one bedroom at most (3.7.A.6); a detached unit must sit in the rear yard (3.7.A.5) and district lot-coverage limits still apply. · Setbacks: Not applicable today. Proposed: the draft sets no zoning setback for ADUs - 'all setbacks for the ADU shall be governed by the NYS Building and Uniform Fire Prevention Code' (Sec. 3.7.A.9); a detached ADU must be in the rear yard (3.7.A.5).

Max size: 600 heated sq ft or 70% of the total floor area of the principal residence, whichever is greater, with an absolute cap of 1,000 heated sq ft for an ADU in an accessory structure (UDO 15.6.F.6.a). Example: a 1,200 sq ft house allows an 840 sq ft ADU; any house of 1,429 sq ft or more allows the full 1,000 sq ft. ADUs do not count toward the rule that all other accessory structures together may not exceed the heated first-floor area of the house (UDO 17.1.F). · Setbacks: 3 ft minimum from the rear lot line for an accessory structure in the established rear setback; 15 ft if the structure is 24 ft or taller (UDO 17.1.E.2). The principal-building rear setback (40 ft N1-A, 35 ft N1-B, 30 ft N1-C, 25 ft N1-D, 20 ft N1-E/F, Table 4-2) does not apply to the ADU. Keep 5 ft between the ADU and the house (17.1.E.3).

Max size: 1,000 sq ft of heated floor area on a single storey, or 1,200 sq ft total across two storeys (UDO Sec. 5.4.2.B.4), and in every case less than the floor area of the primary house. RR District lots of 4 acres or more use a different cap: 50% of the house's heated floor area. On a single-family lot the detached accessory structure may be built as a two-unit duplex ADU as long as both units total no more than 1,200 sq ft (Sec. 5.4.2.B.1.d). · Setbacks: 5 ft for a detached ADU in most residential districts; 3 ft in the RU and RC districts (UDO Sec. 5.4.1.B.1.a-b). An attached ADU (addition) must meet the house's rear yard, which is 25 ft in every RS, RU and RC district (Sec. 7.1.2).

Max size: 800 sq ft gross floor area on lots under 40,000 sq ft; 1,000 sq ft on lots over 40,000 sq ft (Sec. 2.6.3.G), and always less than the principal dwelling's GFA (D.1). GFA counts all conditioned space plus any attached unconditioned space; a manufactured-home ADU is capped at 600 sq ft (D.6). · Setbacks: 5 ft from the rear lot line on lots under 40,000 sq ft; 10 ft on lots over 40,000 sq ft (Sec. 2.6.3.H4). From an alley: 4 ft without parking, 20 ft with parking (H5). Mixed-use districts: 5 ft (Sec. 3.6.2.H4).

Max size: 800 sq ft of floor area (60.50.03.2.C.1). No percentage-of-house rule. A detached ADU can be a new building or a manufactured home (60.50.03.2.B.3). An ADU added to a house that existed on June 30, 2022 is excluded from the zone's floor-area-ratio cap (60.50.03.2.C.4); an ADU built with a new house counts toward FAR (1.40 RMA, 0.80 RMB, 0.60 RMC for single-detached, Table 20.05.15.H.1). · Setbacks: 15 ft in RMA, RMB and RMC (Table 20.05.15.F.3), reduced to 5 ft for a one-story ADU no taller than 15 ft measured from finished grade (60.50.03.2.E.2). No ADU may be placed over any easement (60.50.03.2.E.3).

Max size: 800 sq ft floor area for a single ADU; where two ADUs are built, one may be up to 800 sq ft and the other up to 500 sq ft (BDC 3.6.200(B)(3)(a)). Floor area is measured inside the exterior walls, stairs count once, and space under a ceiling lower than 5 ft is excluded (B)(3)(b). An attached garage or storage room does not count if it has no interior access to the ADU or provides the ADU's parking space (B)(3)(d). A unit over 800 sq ft is reviewed as a duplex, not an ADU. · Setbacks: No ADU-specific setback; the underlying zoning district's rear setback applies (City ADU Zoning Quick Reference Guide: 'Building Setbacks: follow your zoning district's rules'). A detached ADU must sit at least 6 ft from any other dwelling on the lot, measured footprint to footprint (BDC 3.6.200(B)(5); exempt when each structure was legally built before April 1, 2016).

Max size: 800 sq ft or 10% of lot area, whichever is smaller, measured at the exterior walls and including halls, closets, stairs and baths (EC 9.2751(17)(a)1). Up to 300 sq ft of attached unheated garage or storage is not counted (800 sq ft if the ADU is above a garage). In the R-1 zone inside Amazon Neighbors, Fairmount Neighbors or South University: 600 sq ft on lots under 9,000 sq ft, 800 sq ft on lots of 9,000 sq ft or more (EC 9.2751(17)(c)2) · Setbacks: 5 ft (Eugene treats side and rear lot lines alike as 'interior yard' setbacks; EC 9.2751(17)(a)2 and (b)4). Eaves and chimneys may project 2 ft into it. On a flag lot the interior setback is 10 ft (EC 9.2775(5)(e)). An ADU above a garage may sit closer with a 10 ft building separation and a recorded maintenance-access easement (EC 9.2751(17)(a)2.c)

Max size: 800 sq ft of living area or 75% of the main home's living area, whichever is less, measured after the ADU is built (33.205.040.C.1). Living area excludes exterior walls, garages and basement space under a 6 ft 8 in ceiling. Building coverage also cannot exceed the main house's, and all accessory structures together may cover at most 20% of the lot (33.110.245.C.3) · Setbacks: 5 ft in R7, R5 and R2.5; 10 ft in RF, R10 and R20 (Table 110-4). In R7/R5/R2.5 a detached ADU may sit on the rear lot line (0 ft) if it is at least 40 ft from the front lot line, no more than 15 ft tall with 10-ft walls, within a 24 x 24 ft footprint, has no doors or windows facing that lot line and keeps dormers 5 ft off it (33.110.245.C.2.b)

Max size: 900 sq ft or 75% of the main building's gross floor area, whichever is less (SRC 700.007; City ADU and Middle Housing pages, read Sept 2026). The City's free ready-build plan is under 600 sq ft · Setbacks: Not published on the City's ADU page; SRC 700.007 and the zone's accessory-building standards govern (Municode text could not be read in Sept 2026 - bot wall). Confirm with the Planners Desk, 503-588-6213, before drawing the site plan

Max size: No ADU can be permitted today. Pending CB 2025-1545 defines an ADU as not greater than 1,000 sq ft (the lapsed 2018 overlay said under 800 sq ft); the Planning Commission's June 2, 2026 version keeps 1,000 sq ft. · Setbacks: Accessory structures: 5 ft from the rear lot line, or 2 ft where the rear line abuts a way (alley) (§912.04.B). Primary-structure rear setback is 30 ft in the VL, L and M development subdistricts and 15 ft in H (§903.03). Pending bill: converting a garage that already sits in a rear or side setback needs no Administrator's Exception if it encroaches no further (proposed §912.08.C.5).

Max size: 850 sq ft of conditioned floor area (Sec. 54-214.e). If the accessory building uses the reduced side/rear setback exception in Sec. 54-506(f), its building footprint is capped at 600 sq ft instead. · Setbacks: The district's accessory-building rear setback applies. Sec. 54-506(f) lets a qualifying accessory building with a footprint of 600 sq ft or less sit closer to an interior rear line (3 ft as read from the code in July 2026; Municode could not be re-read on Sept. 20, 2026, so confirm the distance and which lot lines qualify with the Zoning Desk).

Max size: 700 sq ft of living space on lots under 10,000 sq ft; 850 sq ft on lots of 10,000 sq ft or more; never larger than the principal house (17.16.030.G.7.a, as amended December 4, 2025). The DADU footprint may not exceed the house footprint, and no other accessory building may exceed 200 sq ft once a DADU is on the lot (G.1.b) · Setbacks: 3 ft minimum for a DADU with a footprint of 850 sq ft or less located behind the house; 10 ft where garage or carport doors open directly onto an alley; a footprint over 850 sq ft must meet the full district rear setback (17.12.040.E.1.a). No building over an easement or a platted setback

Max size: No fixed cap outside the Subchapter F (McMansion) boundary: only 40% building cover and 45% impervious cover (§ 25-2-773(B)). Inside that central-Austin boundary a new unit may not exceed the greater of 0.4 FAR or 2,300 sq ft; the lot total is the greater of 0.55 FAR or 3,200 sq ft for two units and 0.65 FAR or 4,350 sq ft for three (§ 25-2-773(E), as amended by Ord. 20250424-073, eff. May 5, 2025). Garages and lofts count toward gross floor area; carports and porches do not. · Setbacks: 10 ft (SF-1/SF-2/SF-3 base district, § 25-2-492), reduced to 5 ft when the lot is adjacent to an alley or to a lot with a use permitted in a multifamily or less restrictive district (§ 25-2-773(B)(3)).

Max size: Greater of 700 sq ft or 25% of the main structure's floor area, minimum 200 sq ft (Sec. 51A-4.510(c)(2)(C)(i), overlay lots). Outside an overlay the general accessory-structure cap applies: one structure may not exceed 25% of the main building's floor area and all accessory structures together 50%, excluding parking (Sec. 51A-4.209(b)(6)(E)(vii)(dd)-(ee)). · Setbacks: 3 ft when the structure is under 15 ft tall (Sec. 51A-4.510(c)(2)(B)(ii)); at 15 ft or taller the base district rear yard applies, 5 ft for single-family structures in R-5(A) and R-7.5(A) (Sec. 51A-4.112). Outside an overlay Sec. 51A-4.403(b)(2) lets an accessory structure under 15 ft sit 3 ft from a rear line on an alley, or on the line where there is no alley.

Max size: No numeric cap for a habitable accessory building in § 5.301. The limits are the district's lot coverage counting every roof on the lot (§ 5.301(a)(3): 50% in A-5, 45% in A-7.5, 40% in A-10, 30% in A-21 and A-43, 20% in A-2.5A; accessory habitable area counts, § 9.101 'lot coverage'), the district setbacks, the building code and a height no greater than the house (§ 5.301(c)(2)). The 120-to-400-square-foot table in § 5.301(b) applies only to non-habitable sheds and workshops, not to a habitable unit · Setbacks: 5 ft in A-5, A-7.5 and AR; 10 ft in A-10 and A-21; 25 ft in A-43 and A-2.5A. A habitable accessory building must meet the side and rear setback of the primary structure for its district (§ 5.301(a)(2)). The 3-ft reduction in § 4.705(d)(8) is for detached garages behind the rear wall of the house, not habitable space, and structures may not sit in easements

Max size: No floor-area cap: §4.06.03 sets location, permit, rental and setback standards for a Garage Apartment or Guest House but no maximum size. What binds is the district's maximum lot coverage for all buildings: 45% in SF-7, SF-8.5 and SF-10, 40% in SF-12.5, 30% in SF-16, 20% in RE and 55% in OTR (§2.06.04). A detached unit is a Guest House, defined in §7.01.01 only as "an accessory building used to house guests of the owner(s)" — confirm with Development Services before adding a kitchen · Setbacks: Same as the primary structure. Figure 4.06.04.1 gives the row "Guest House or Garage Apartment" setback note D, "Same as Primary Structure Setback", for front, side and rear, so it does not get the 3-foot (note A) or 10-foot (note B) rear setback ordinary accessory buildings use (§4.06.03(D), §4.06.04(G)). That is 30 feet in AG, RE, SF-16, SF-12.5, SF-10, SF-8.5, SF-7 and 2F, and 8 feet (20 feet for a garage facing an alley) in OTR (§2.06.04)

Max size: 1,500 sq ft. § 42-1 defines single-family residential to include 'a detached second dwelling unit of not more than 1500 square feet'; the cap was increased by the Livable Places amendments (Ord. 2023-801, eff. Nov 27, 2023). The code does not say how the area is measured; deed restrictions may set a lower cap or bar a second unit entirely. · Setbacks: Chapter 42 sets no interior rear building line for a single-family lot; it sets 10 ft along a rear lot line that abuts a collector or local street (§ 42-156) and 3 ft along a shared driveway 18 ft or wider (§ 42-159). Interior rear lines are governed by deed restrictions, the plat and the Building Code's fire-separation rules — confirm with the Houston Permitting Center.

Max size: 400 sq ft minimum; maximum 1,100 sq ft or 50% of the gross habitable floor area of the main dwelling, whichever is more restrictive, and never above the district's maximum lot coverage (§15.1800.2.C–E). The city's permit handout lists 45% total coverage in SF-6, SF-7, SF-9 and 2F with garage and accessory buildings capped at 10% of the lot (25%/10% in SF-20) — confirm current coverage limits with Building Inspections · Setbacks: §15.1800 sets no cottage-specific rear setback — the rear-yard rule of your zoning district and the accessory-building placement rules of Article 13 apply. The current Article 9 and 13 text could not be read in September 2026, so confirm your district's rear-yard figure with Plano Planning before designing

Max size: N/A: a detached second dwelling is not a permitted use. Detached accessory buildings are capped instead: all detached structures together, garages included, may occupy no more than 8% of the lot area and may not exceed 40% of the floor area of the principal dwelling (Art. IV, Sec. 4(d)(2); Art. VII, Sec. 4(d)(2)). Servants' quarters, the only accessory living space allowed, may not have kitchen facilities or separate utility connections (Art. I, Sec. 2) · Setbacks: N/A for ADUs. The district rear setback is 25 ft, but a detached garage, carport or other accessory building may extend into it with a minimum 3 ft from the rear lot line, or 18 in where the rear lot line adjoins an alley (Art. IV, Sec. 4(g)(2); Art. VII, Sec. 4(g)(2)). Building Inspection measures these to the roof overhang

Max size: The larger of 800 sq ft gross floor area or 50% of the main house's gross floor area, capped at 1,600 sq ft (UDC 35-371; IB 402 FAQ 1). Every lot may therefore have an ADU of at least 800 sq ft regardless of the size of the main house. · Setbacks: 5 ft standard for a detached ADU; may be reduced to 3 ft if the structure has no eave overhang within 3 ft of the line, and walls within 5 ft of the line must be fire-rated under the IRC (IB 402 FAQ 2; DSD ADU page). The ADU must be located in the rear of the lot (IB 402 FAQ 4).

Max size: 1,000 sq ft of gross floor area (21A.40.200.J.1). Only the ADU's floor area counts when the building also holds a garage or other accessory use; stairs to a second-level ADU, loft space under 7 ft and a storage-only basement with no internal connection are excluded (J.3). A covered patio up to 120 sq ft does not count toward the cap but does count toward lot coverage (H.3). Accessory buildings together may cover at most 50% of the rear yard in single/two-family districts (ADU Handbook v2.2). · Setbacks: 3 ft from the rear property line for a detached ADU (21A.40.200.E.3), rising 1 ft per foot of height above 17 ft (F.1.a). Additions, including a second storey on an existing garage, must meet these setbacks; a conversion with no expansion may keep the garage's existing setbacks (E.3 notes). Second-storey windows on a wall within 10 ft of a rear or side line must be clerestory (sill 6 ft up) unless they face the house, an alley, or a commercial or non-residential lot (K).

Max size: First floor of the detached accessory building may not exceed the greater of (a) one-third of the floor area of the principal dwelling's first floor or (b) 350 sq ft on lots of 2,500 sq ft or less / 500 sq ft on lots larger than 2,500 sq ft (Sec. 7-203(C)(1)). Only the first floor is capped; an upper floor is allowed within the 20 ft height limit. For this test, floor area includes space otherwise excluded by Sec. 2-145(A)(12)/(B)(14). · Setbacks: Detached ADU building allowed in the required rear yard: at least 1 ft from the rear lot line including architectural features (unless the zone requires less); 3 ft if a wall with windows or doors faces that line; 2.5 ft for portions taller than 13.5 ft and under 16 ft; 5 ft for portions over 16 ft; and, outside the historic districts, 5 ft including overhang where a neighbor's window or door sill under 20 ft high sits within 3 ft of the shared line (Sec. 7-203(C)(3)).

Max size: Gross floor area capped at the lesser of 750 sq ft or 35% of the combined floor area of house plus AD when the house is at least 1,000 sq ft; 500 sq ft or 45% when the house is under 1,000 sq ft (§12.9.2.A.2(e)). A detached accessory building approved after May 18, 2019 may hold an AD only if its footprint is 560 sq ft or less in R-5/R-6, 650 sq ft or less in the other R districts (§12.9.2.A.2(d)). GFA counts attic and basement space (§3.1.1). · Setbacks: New detached AD building: 5 ft to the wall on interior lots; 10 ft to the eave on corner lots (§12.9.2.A.2(b)). The general §3.2.6 rule that no accessory building may be closer than 8 ft to any wall of the main dwelling also applies.

Max size: 1,200 sq ft of floor area (LUC 20.20.120; confirmed on the City's 2026 Pre-Approved Plans page). The Director may approve a larger unit when it is an addition to, or a conversion of, an existing detached accessory structure; a converted guest cottage is exempt from the cap if not enlarged. The council draft also excluded up to 250 sq ft of garage or unheated storage per ADU - confirm that clause with Land Use Review · Setbacks: Detached ADUs use the middle-housing setbacks in LUC 20.20.538 Table C.1, which the council draft set at 10 ft in SR-3 through MDR-2 and 15 ft in LL-1, LL-2, SR-1 and SR-2; a DADU may sit on a rear lot line that abuts a public alley (LUC 20.20.120.D.2; RCW 36.70A.681(1)(i)). Attached ADUs use the main house's rear setback. Confirm the adopted table with Land Use Review, 425-452-4188

Max size: 1,200 sq ft: "An accessory dwelling unit may be developed up to 1,200 square feet" (BMC 12.14.135(D)(1)), 200 sq ft above the state floor (RCW 36.70A.681(1)(f)). A conversion of existing space may exceed 1,200 sq ft with the community development director's approval, up to 40 percent of the primary unit's gross floor area. Detached ADUs are exempt from the BMC 12.14.130 five-percent-of-lot cap on accessory buildings (BMC 12.14.135(D)(2)); hard surface coverage is the real limit · Setbacks: Same as the house. "Detached accessory dwelling units shall maintain the same rear yard setback as primary structures, except for those accessory dwelling units located on an alley, in which case the setbacks for structures adjoining alleys in BMC 12.14.060 shall apply" (BMC 12.14.070(B), quoted on the city's ADU checklist). Zone minimums: 35 ft in R-C, 15 ft in R-L1 and R-L2, 10 ft in R-M1 through R-M4; on an alley 0 ft, 3 ft for a garage door (BMC 12.14.030(A))

Max size: 1,200 sq ft of gross floor area (KZC 115.07(4)), above the 1,000 sq ft floor in RCW 36.70A.681(1)(f). Not counted: area under 5 ft of ceiling, uncovered rooftop decks or at-grade patios, and up to 200 sq ft of other exterior elements. Ordinance 4905 took ADUs out of the KZC 115.08 accessory-structure cap. Floor area ratio still bites: only the first 500 sq ft (lot under 8,500 sq ft) or 800 sq ft (8,500 sq ft and up) of a detached ADU behind the house is exempt from F.A.R. (KZC 115.42(1)(c)-(d)). · Setbacks: 10 ft, the house standard (KZC 15.30.060), relaxed by KZC 115.115(3)(o): a detached ADU without alley access may sit 5 ft from the rear line if the part inside the required rear yard is no taller than 15 ft above ABE and the rear yard does not abut an access easement treated as a rear line; a detached ADU may extend to a rear line abutting an alley if its eaves stay on the lot and sight distance (KZC 115.135) is met (RCW 36.70A.681(1)(i)). A converted garage keeps its setbacks (KZC 115.07(6)).

Max size: 1,000 sq ft: "The total square footage of an ADU shall not exceed 1,000 square feet" (RZC 21.04.1110.C.3.a) — exactly the floor RCW 36.70A.681(1)(f) sets. On a site over 10,000 sq ft the Administrator may allow more if the ADU is an affordable unit or a public benefit is provided (C.3.c). Watch the accessory-structure rule: accessory footprints may not exceed 60 percent of the house's ground-floor living area, excluding garage (RZC 21.04.1120.C.2.a) · Setbacks: 5 ft in the Neighborhood Residential zone, the same as the house (Table 21.08.300.A); accessory structures in NR and NMU "shall comply with the underlying setback regulations of the zone" (RZC 21.04.1120.C.5). The alley setback is 2 ft, and RZC 21.04.1110.C.2.b goes further: detached ADUs may be sited immediately abutting a lot line that abuts a public alley or right-of-way, overriding other setbacks — broader than RCW 36.70A.681(1)(i), which covers alleys only

Max size: 1,000 sq ft of floor area: "The ADU must not exceed a floor area of 1,000 square feet" (SMC 21.05.010.C(5)(a)(iii)) — the floor RCW 36.70A.681(1)(f) sets, not a foot more. ADUs are listed as "Exempt" from the 50 percent residential floor area ratio in R-1 through R-8, and SMC 21.04.030.C condition (10) exempts them from hardscape coverage (30 percent in R-1, 40 percent in R-4) and FAR calculations on a single-family lot. The 3,000 sq ft maximum building footprint per building still applies. · Setbacks: 5 ft for a stand-alone detached ADU in all six zones (SMC 21.04.030.C, Detached Accessory Dwelling Setbacks, conditions (4) and (7)). The house itself keeps 30 ft in R-1, 20 ft in R-8, R-12 and R-18, and a 12 to 20 ft minimum in R-4 and R-6 by building size. Condition (7): the 5-ft standard "only applies to stand-alone detached accessory dwelling units" — a DADU combined with a garage or covered patio takes the accessory-structure setback: 10 ft in R-1 through R-8, 5 ft in R-12 and R-18.

Max size: 1,000 sq ft of gross floor area for an ADU with up to two bedrooms; 1,200 sq ft with three or more bedrooms (SMC 23.42.022.G.1, as amended by Ord. 127376). Not counted: up to 250 sq ft of attached garage, any story that is underground, and up to 35 sq ft of long-term bike parking. A 1,500 sq ft ADU is allowed only on a Lowrise lot inside a frequent transit service area that has not been sold for more than $1,000 in 20 years (community land trust case). ADU floor area does count toward the lot's FAR, lot coverage and density · Setbacks: 5 ft for an ADU in Neighborhood Residential zones; 0 ft where the rear lot line abuts an alley (Table A for 23.44.090, footnote 3). The house itself needs 15 ft (10 ft with three or more principal units), so the cottage can sit closer to the back line than the house can. Structures containing floor area must be 5 ft apart, eave to eave (23.44.100.A)

Max size: 1,000 sq ft of floor area (SMC 17C.300.110(A)(2)). Building footprint up to 1,200 sq ft in every residential zone (Table 17C.111.205-2), counted within the lot's total building coverage cap of 50% in RA, 65% in R1, 80% in R2 and 100% in RMF/RHD (Table 17C.111.205-1, note 5). · Setbacks: 0 ft where the rear lot line abuts an alley; 5 ft where there is no alley (Table 17C.111.205-2). An existing garage or shed already inside a rear or side setback may be converted in place (SMC 17C.300.130(B)(4), 17C.111.240), but any added floor area puts the whole structure under current setbacks.

Max size: 1,000 sq ft of habitable area, excluding garage and other non-living areas (TMC 13.06.080.A.5.b). A Backyard Building is also limited to 40 ft wide (75 ft in UR-3) and 40 ft deep, and the lot's total floor area must stay within the UR FAR cap (UR-1: 0.6 for 1-2 units, 0.8 for 3+; UR-2: 0.8/1.0; UR-3: 1.0/1.2; TMC 13.06.020.F.1). · Setbacks: 15 ft in UR-1/UR-2, 10 ft in UR-3; 0 ft from an alley, and the rear setback may be measured from the alley centerline (TMC 13.06.020.F.1; 13.06.100.F.4.b). Retaining a 12-in DBH tree cuts it to 10 ft (UR-1/2) or 7.5 ft (UR-3). Buildings on the same lot must be 6 ft apart, 10 ft if either is over 25 ft tall.

Max size: 1,000 sq ft or less to count as an ADU (VMC 20.150 definition; City ADU page). A larger detached unit is still allowed, but it is treated as a regular middle-housing unit and pays full impact fees. The only floor is the Washington State Building Code minimum for a dwelling unit. · Setbacks: 5 ft minimum from the rear lot line; 0 ft from an alley (VMC 20.420.100.D, Flex-Plex building type). A detached ADU must also sit 10 ft from every other structure on the lot - house, garage, sheds, decks and stairs - or meet extra fire-code separation such as sprinklers or 1-hour rated construction (City ADU page).

Max size: 300 to 1,500 sq ft of habitable floor area (WMC 21.41.020(3)(b)), 500 sq ft above the 1,000 sq ft floor in RCW 36.70A.681(1)(f). Habitable floor area is gross floor area minus vehicle parking, covered and open-air floors and space under 5-ft ceilings, so a garage bay or low attic does not count. Building coverage (Table 21.32.050(1)) is the practical cap: R-1 steps from 40% on lots under 5,000 sq ft to 15% at 43,560 sq ft and over; R-4 35%; R-6 50%; R-8 55%; R-12 and R-18 60-65% · Setbacks: No separate rear setback: Table 21.32.030(2) sets one "minimum setback from interior property lines", 10 ft in R-1 (5 ft on R-1 lots under 15,000 sq ft, note 2) and 5 ft in R-4, R-6, R-8, R-12 and R-18. A detached ADU "may have the zoning setback reduced to zero from any property line abutting a dedicated public alley" (WMC 21.41.020(3)(c)). Add a 10-ft building setback from the edge of any wetland or riparian buffer (WMC 21.51.050(3))