2021 Code Changes to Residential Building Envelope
Every three years, the International Code Council (ICC) goes through the process of updating the building codes outlined in the International Energy Conservation Code (IECC). The IECC is the model energy code in the U.S., and updates to the 2021 edition were just finalized by the ICC. Changes to the codes come from ICC staff, industry groups, government, and the general public. The 2021 IECC contains a large number of changes that impact building energy use.
The 2021 Residential IECC calls for increased R-values in attic, slab, and continuous insulation for walls. It also includes new options in the prescriptive tables for insulation on wood-framed walls and basement walls. Increases were also made to performance requirements for windows in most climate zones. The table below highlights the insulation R-value changes, and the cells outlined in yellow indicate a change from the 2018 code to the 2021 code.