WAC 296-24-76515
WAC 296-24-76515. Length of stairways
Long flights of stairs, unbroken by landings or intermediate platforms, should be avoided. Consideration should be given to providing intermediate platforms where practical and where such stairways are in frequent use. You must ensure that stairway platforms are no less than the width of a stairway and a minimum of 30 inches in length measured in the direction of travel.