What size does an attic access opening need to be?

Minimum rough-framed opening of 22 by 30 inches, required when the attic is over 30 sq ft with at least 30 inches of clear height (IRC R807.1).

The IRC requires an attic access opening where an attic has an area greater than 30 square feet and a vertical clear height of 30 inches or more. The rough-framed opening must be at least 22 inches by 30 inches.

There must be at least 30 inches of clear headroom above the access opening, measured vertically from the opening into the attic space.

If equipment such as an air handler is located in the attic, the opening must be large enough to remove that equipment. The access is typically placed in a hallway or other readily accessible location.