Section 642-6-6 - MUBEC STRETCH CODE1. Appendix RA, RB, RC of the 2021 IECC is intended to provide flexibility to permit the use of more than one approach or technique to achieve compliance with the Stretch Code. The approach to be used for achieving compliance with the MUBEC Stretch Code is at the discretion of the building owner and the owner's designer. Where new construction satisfies the provisions of Appendix CA, CB, CC, RA, RB, RC of the 2021 IECC it will be considered in compliance with the MUBEC Stretch Code.