If the access is located in the ceiling the minimum unobstructed headrom above the opening must be 30 inches measured vertically at some point over the access.
Minimum attic access size irc.
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.
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.
See the california mechanical code for access requirements where mechanical equipment is located in attics.
Where 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.
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.
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.
The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.
The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.
The rough framed opening must be a minimum of 22 inches by 30 inches.
Chapter 10 city amendment.
According to the 2006 international residential code r807 1 attic access homes with combustible materials in the ceiling and roof construction must have an access to attic areas that exceeds 30 square feet and with a vertical height of 30 inches or greater.
This 20 limitation applies to the minimum 30 height only low clearance attics.
See section m1305 1 3 for access requirements where mechanical equipment is located in attics.