On June 4th 2019, acceptance criteria AC509 (proposed new acceptance criteria for concrete walls built using construction-scale 3D printing) was unanimously approved by a committee of building officials during the ICC-ES evaluation committee meeting. AC509 is the result of collaborations between CC Corp and ICC-ES and its approval is a major milestone in the history of construction-scale 3D printing. This event may be regarded as the first major regulatory step towards addressing the building code compliance issue of 3D printed buildings.