The provisions of this chapter shall not apply to:
1. Professional engineers licensed under chapter 542B.
2. Persons acting under the instruction, control, or supervision of, and those executing the plans of, a licensed architect or a professional engineer licensed under chapter 542B, provided that such unlicensed persons shall not be placed in responsible charge of architectural or professional engineering work.
3. Superintendents, inspectors, supervisors, and building trades craftspersons while performing their customary duties.
C93, §544A.17