This bill adopts the 2018 International Building, Plumbing, Mechanical, Fuel Gas, and International Existing Building Codes, as well as the commercial provisions of the 2018 International Energy Conservation Code, which require all new commercial buildings constructed after July 1 to meet higher energy efficiency standards. The bill also adopts Appendix Q of the 2018 International Residential Code, which outlines codes for tiny homes. 

The bill requires that a building inspector give written notice the same day of the inspection and provide a code reference for violations upon request. Regarding multi-family units and townhomes, the bill lowers the threshold for air changes per hour, which measure air leakage rates, from three to five. Single-family homes must meet a 3.5 air changes per hour. The bill requires whole-house mechanical ventilation systems in residential homes to meet certain efficacy standards for energy efficiency. 

The bill clarifies codes and required agreements for installations within shared walls between condos and townhomes.