For windows located in an IRC structure:
KMC 21.06.215: A building permit is not required when replacing an existing window in an IRC structure as long as no alteration to any structural member is required.
NOTE: Even when a building permit is not required, the window related code requirements listed below must still be met. Skip to Step 4.
A building permit is required when installing a window where none was present, and when replacing an existing window if any structural alterations are necessary (such as when a larger header is required to be installed because the replacement window is wider than the original window). Skip to Step 3.
For windows located in an IBC structure:
There is no situation where a window installation or replacement in an IBC structure is exempt from requiring a building permit. Go to Step 3.