The Occupational Safety and Health Administration (OSHA) has received thousands of questions and requests for clarification about their occupational health and safety standards from employers, individuals, unions, and other organizations throughout the years. When OSHA responds to these questions, they typically do so through a Letter of Interpretation. These letters are posted on the OSHA website, and address many topics; they are a great resource for employers because they may answer your question(s) about a particular standard or topic. However, be aware that the letters only address the specific question asked, and may not apply to your exact situation. Also, the letters are strictly interpretations issued by OSHA, and do not alter the meaning of the actual OSHA standards.  The intent of this newsletter series will be to provide insight into some of the more unique interpretations provided by OSHA.

This article (Part 7) will address requirements for attachable scaffold ladders used in construction; toe-hold minimum distance requirement. and discuss briefly 29 CFR 1926.500; General Duty Clause. 

Question: What OSHA construction scaffold requirements apply to attachable (bolt-on) scaffold ladders? Is fall protection required for workers as they climb up or down these ladders??

OSHA responded that under 29 CFR Part 1926 Subpart L (Scaffolds), §1926.451(e)(2) details the requirements for use of "portable, hook-on and attachable ladders..." Section 1926.451(e)(2) requires that:

(i) Portable, hook-on and attachable ladders shall be positioned so as not to tip the scaffold;

(ii) Hook-on and attachable ladders shall be positioned so that their bottom rung is not more than 24 inches (61 cm) above the scaffold supporting level;

(iii) When hook-on and attachable ladders are used on a supported scaffold more than 35 feet (10.7 m) high, they shall have rest platforms at 35-foot (10.7 m) maximum vertical intervals.

(iv) Hook-on and attachable ladders shall be specifically designed for use with the type of scaffold used

(v) Hook-on and attachable ladders shall have a minimum rung length of 11 1/2 inches (29 cm); and

(vi) Hook-on and attachable ladders shall have uniformly spaced rungs with a maximum spacing between rungs of 16 3/4 inches.

As you can see from §1926.451(e)(2)(iii), when attachable ladders are used on supported scaffolds more than 35 feet high, they must have rest platforms at no more than 35-foot intervals. There is no requirement in the standard that workers use fall protection while climbing up or down these ladders.

Under the terms of the standard, these six items for portable scaffold ladders are clearly defined, however in practice they are often misused.  We will look at some common errors that are made when these scaffold access ladders are utilized in the field. 

The first mistake that has been observed in the field is the assumption that scaffold frames are an allowable means for access.  While utilizing the crossbraces is specifically prohibited in 1926.451(e)(1), it is often assumed that frames that have the appearance of ladder rungs are compliant.  Often the manufacturer specifically excludes their frames from being used for access and requires an attachable ladder instead.  On the other hand, there are some scaffolding manufacturers that do allow for their frames to be used and they have been designed to meet these requirements.  Compare the two images below.  Can you tell which one of these has a compliant built in ladder system?  The answer should be clear, that figure 2 is compliant.  More often than not, masons and other trades will incorrectly assume that Figure 1 frame is a viable option. 



Figure 1                                                                                                                                                          Figure 2

Another common mistake relating to scaffold access is the requirement for rest platforms at heights exceeding 35’.  This requirement is often overlooked and can also vary with different manufacturers.  An example of this is the Hydro-Mobile mast climber scaffolding commonly used in construction for masonry requires a rest platform at 30’.  Any manufacturer requirement would automatically supersede OSHA requirements.  Again, this is a good reminder to make sure you are referencing the manufacturers requirements for use no matter the type of scaffolding you are utilizing. 

Finally, there is a common issue in which an assortment of scaffolding components, from different manufacturers, are used to complete a scaffolding system.  This includes any portable attachable ladders.  The scaffolding standard specifically states that hook-on and attachable ladders must be specifically designed for use with the type of scaffold in use.  It is recommended that an extension ladder be used as an alternative if a compliant attachable ladder is not available. 

Question 2: Is there a toe-hold minimum distance requirement for attachable ladders used on supported scaffolds?

The scaffold standard is silent about toe-hold clearance distances for attachable ladders used on supported scaffolds. However, under the "General Duty Clause" (Section 5(a)(1)) of the Occupational Safety and Health Act, employers must "furnish to each of [its] employees from recognized hazards that are causing or are likely to cause death or serious physical harm...." It is recognized in the industry that there must be sufficient toe-hold clearance on ladder steps to enable the workers to safely use the rungs.

It should be noted that seven inches of clearance is generally recognized minimum; see, for example, the American National Standards Institute standard A14.3-2002, section, which calls for 7 inches of clearance behind ladders. Note also that in §1926.1053(a)(13), the shortest clear distance permitted behind a fixed ladder is 7 inches (except for an elevator pit ladder, in which case it is 4.5 inches)

Cited Source:  “Department of Labor Logo United States Department of Labor.” Requirements for Attachable Scaffold Ladders Used in Construction; Toe-Hold Minimum Distance Requirement. | Occupational Safety and Health Administration,