Old shingles are to be left intact on a roof with a 6:12 slope. The climate is severe and hail must be accounted for. According to code, the ice shield shall extend from the eave to a minimum of what distance inside the exterior wall lined?

Old shingles are to be left intact on a roof with a 6:12 slope. The climate is severe and hail must be accounted for. According to code, the ice shield shall extend from the eave to a minimum of what distance inside the exterior wall lined?