Senate Study Bill 3070 - Introduced SENATE FILE _____ BY (PROPOSED COMMITTEE ON LOCAL GOVERNMENT BILL BY CHAIRPERSON WEBSTER) A BILL FOR An Act relating to county and city regulation of accessory 1 dwelling units. 2 BE IT ENACTED BY THE GENERAL ASSEMBLY OF THE STATE OF IOWA: 3 TLSB 5633XC (2) 91 ms/js

S.F. _____ Section 1. Section 331.301, subsection 29, paragraph a, 1 Code 2026, is amended to read as follows: 2 a. A county shall allow a minimum of one accessory dwelling 3 unit on the same lot as a single family residence within a 4 zoning district where a single family residence is an allowed 5 principal use, in accordance with the following conditions: 6 (1) An accessory dwelling unit shall comply with all 7 applicable building regulations as defined in chapter 103A . 8 (2) An accessory dwelling unit shall not exceed one thousand 9 square feet or fifty percent of the size of the single family 10 residence, whichever is larger. The size calculation of an 11 accessory dwelling unit shall exclude unfinished basements. 12 (3) An accessory dwelling unit shall be prohibited or 13 limited only to the extent that a state historic building code 14 restriction, as adopted by a county in accordance with section 15 103A.43, subsection 3 , a deed restriction , or a rule of a 16 common interest community, as defined in section 499C.1 , limits 17 or prohibits the construction or use of an accessory dwelling 18 unit. The imposition of an ordinance, motion, resolution, or 19 amendment regulating accessory dwelling units that is more 20 restrictive when applied to a common interest community than 21 when applied to a single family residence is prohibited. 22 An accessory dwelling unit proposed for a lot within a 23 historic preservation district as defined in section 15.445, 24 subsection 3, shall be regulated only to the extent that the 25 historic preservation commission as defined in section 15.445, 26 subsection 2, determines that the proposed accessory dwelling 27 unit would be incongruous with the historical, architectural, 28 archaeological, or cultural aspects of the district, and enters 29 into its records the reasons for such determination. 30 (4) If a manufactured home as defined in section 435.1, 31 subsection 3 , or a mobile home as defined in section 435.1, 32 subsection 5 , is used as an accessory dwelling unit, the 33 manufactured home or mobile home shall be converted to real 34 property by being placed on a permanent foundation and assessed 35 -1- LSB 5633XC (2) 91 ms/js 1/ 4

S.F. _____ for real estate taxes pursuant to section 435.26 . 1 Sec. 2. Section 331.301, subsection 29, paragraph e, Code 2 2026, is amended by adding the following new subparagraph: 3 NEW SUBPARAGRAPH . (5) “Size” means the gross living area 4 of the primary dwelling unit excluding garages, decks, and 5 unheated porches. 6 Sec. 3. Section 364.3, subsection 23, paragraph a, Code 7 2026, is amended to read as follows: 8 a. A city shall allow a minimum of one accessory dwelling 9 unit on the same lot as a single family residence within a 10 zoning district where a single family residence is an allowed 11 principal use, in accordance with the following conditions: 12 (1) An accessory dwelling unit shall comply with all 13 applicable building regulations as defined in chapter 103A . 14 (2) An accessory dwelling unit shall not exceed one thousand 15 square feet or fifty percent of the size of the single family 16 residence, whichever is larger. The size calculation of an 17 accessory dwelling unit shall exclude unfinished basements. 18 (3) An accessory dwelling unit shall be prohibited or 19 limited only to the extent that a state historic building 20 code restriction, as adopted by a city in accordance with 21 section 103A.43, subsection 3 , a deed restriction , or a rule 22 of a common interest community, as defined in section 499C.1 , 23 limits or prohibits the construction or use of an accessory 24 dwelling unit. The imposition of an ordinance, motion, 25 resolution, or amendment regulating accessory dwelling units 26 that is more restrictive when applied to a common interest 27 community than when applied to a single family residence is 28 prohibited. An accessory dwelling unit proposed for a lot 29 within an area designated as an area of historical significance 30 shall be regulated to the extent that the city or commission, 31 pursuant to section 15.459, subsection 3, determines that the 32 proposed accessory dwelling unit would be incongruous with the 33 historical, architectural, archaeological, or cultural aspects 34 of the area, and enters into its records the reasons for such 35 -2- LSB 5633XC (2) 91 ms/js 2/ 4

S.F. _____ determination. 1 (4) If a manufactured home as defined in section 435.1, 2 subsection 3 , or a mobile home as defined in section 435.1, 3 subsection 5 , is used as an accessory dwelling unit, the 4 manufactured home or mobile home shall be converted to real 5 property by being placed on a permanent foundation and assessed 6 for real estate taxes pursuant to section 435.26 . 7 Sec. 4. Section 364.3, subsection 23, paragraph e, Code 8 2026, is amended by adding the following new subparagraph: 9 NEW SUBPARAGRAPH . (5) “Size” means the gross living area 10 of the primary dwelling unit excluding garages, decks, and 11 unheated porches. 12 EXPLANATION 13 The inclusion of this explanation does not constitute agreement with 14 the explanation’s substance by the members of the general assembly. 15 Under current law, a county or city shall allow a minimum of 16 one accessory dwelling unit (ADU) on the same lot as a single 17 family residence in accordance with certain conditions. 18 This bill specifies that a county or city shall allow a 19 minimum of one ADU on the same lot as a single family residence 20 within a zoning district where a single family residence is an 21 allowed principal use. 22 Under current law, an ADU shall not exceed 1,000 square 23 feet or 50 percent of the size of the single family residence, 24 whichever is larger. The bill specifies that the size 25 calculation of an ADU shall exclude unfinished basements. 26 Under current law, an ADU shall be prohibited or limited only 27 to the extent that a state historic building code restriction, 28 as adopted by a county or city in accordance with Code section 29 103A.43, would prohibit or limit the ADU. The bill strikes 30 this condition. The bill requires that an ADU proposed for 31 a lot within a historic preservation district as defined in 32 Code section 15.445, or an area designated as an area of 33 historical significance pursuant to Code section 15.459, shall 34 be regulated only to the extent that the historic preservation 35 -3- LSB 5633XC (2) 91 ms/js 3/ 4

S.F. _____ commission or city determines that the proposed ADU would be 1 incongruous with the historical, architectural, archaeological, 2 or cultural aspects of the district, and enters into its 3 records the reasons for such determination. 4 The bill defines “size” to mean the gross living area of the 5 primary dwelling unit excluding garages, decks, and unheated 6 porches. 7 -4- LSB 5633XC (2) 91 ms/js 4/ 4