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Exterior Door Undercuts
- Thread starter Phil B
- Start date
In the IECC. The IECC requirements do not directly say you cannot undercut. However, undercutting increases air leakage, which is regulated for both commercial and residential buildings.
For commercial buildings, Section C402.5.2 (2018 edition, or C402.5.4 2021 edition) limits air leakage for fenestration. For swinging doors, the maximum leakage is 0.20 cfm/sq. ft.
For residential buildings, Section R402.4.3 (2018 and 2021 editions) limits air leakage for swinging doors to 0.50 cfm/sq. ft. However, there is an exception for site-built doors. However, I would not consider undercutting to be site-built.
For commercial buildings, Section C402.5.2 (2018 edition, or C402.5.4 2021 edition) limits air leakage for fenestration. For swinging doors, the maximum leakage is 0.20 cfm/sq. ft.
For residential buildings, Section R402.4.3 (2018 and 2021 editions) limits air leakage for swinging doors to 0.50 cfm/sq. ft. However, there is an exception for site-built doors. However, I would not consider undercutting to be site-built.