To convert your attic to living space you cannot provide access via a ladder.
Attic access code requirements.
Your attic may presently have a fixed ladder a pull down ladder or no ladder at all.
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 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.
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.
The rough framed opening.
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.
What your attic probably does not have is a set of code compliant stairs.
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.