Minimum Attic Opening Size

Minimum clearance required behind opening.

Minimum attic opening size.

Minimum opening size the 2012 international residential code requires an attic access opening for attics with an area greater than 30 square feet and a vertical height in excess of 30 inches. The rough opening cannot be less than 22 inches by 30 inches and must be located in a hallway or other readily accessible location. One is a minimum for any attic which has the required 30 headroom vertical height. When the access is located in a ceiling minimum unobstructed headroom in the attic space shall be 30 inches 762 mm at some point above the access measured vertically from the bottom of ceiling framing members.

Minimum vertical height of 30 inches measured from the top of the ceiling framing members to the bottom of the roof framing members. Minimum clearance required above attic opening. If mechanical equipment or appliances are housed in the attic there must be an unobstructed passageway large enough for the removal of the appliance. Note about attic clearance.

The access opening should be located in a hallway or other readily accessible location and minimum 22 x 30. For smaller attic openings with a minimum measurement of 18 x 24 you will need to measure the swing clearance inside the attic space. If the access is located in the ceiling the minimum. If the opening is located in a wall the 30 inch dimension must be vertical.

When located in a wall the opening shall be a minimum of 22 inches wide by 30 inches high 559 mm wide by 762 mm high. The 2007 california building code requires a minimum attic access opening of 20 inches by 30. The other is minimum for attics containing appliances and this latter one is more restrictive as it also includes where such dimensions are large enough to allow removal of the largest appliance meaning that the opening may actually be required to be. An attic access opening runs between the ceiling joists whenever possible.

Unobstructed headroom of at least 30 inches must be available above the attic opening. If there are no obstructions on the passageway to the attic furnace and it has a minimum 6 feet 1829 mm height and 22 inches 559 mm width along its entire run the walkway length limit goes up to 50 feet 15250 mm in irc international residential code and has no limit in umc universal mechanical code. Tuesday january 28 2020. To mount assist arm on attic floor 3 4 in.

The rough framed opening must be a minimum of 22 inches by 30 inches. Deep minimum the full width of opening must be present in attic. If the attic space is smaller than these specs then an access hatch is not required.