PDFWAC 296-874-20022
Make sure portable, hook-on, and attachable ladders meet these requirements.
(1) You must position portable, hook-on, and attachable ladders so they do not tip the scaffold.
(2) You must make sure hook-on and attachable ladders meet all of the following:
(a) Specifically designed and used for that type of scaffold;
(b) Have rungs that are:
(i) Uniformly spaced;
(ii) Not more than sixteen and three-quarters inches apart;
(iii) At least eleven and one-half inches (29 cm) long;
(iv) Lined up vertically between rest platforms.
(3) You must position the bottom rung not more than twenty-four inches (61 cm) above the scaffold supporting level.
(4) You must have rest platforms at vertical intervals not greater than twenty-four feet (7.3 m) on supported scaffolds.