learn how to measure extension ladders

How to Measure an Extension Ladder

OSHA, the Occupational Safety and Health Administration, has established safety guidelines for measurement and use of extension ladders. The extension ladder measurement guidelines take into consideration the overall extended length of the extension ladder and the distance between rungs. Most of the other OSHA measurement guidelines are for ladder manufacturers like Sunset Ladder and Scaffold to consider when manufacturing safe extension ladders.

ez lift fiberglass ladder as light as aluminum ladderDuty Ratings and Extension Ladders
Type 1 and Type 1A extension ladders, also called Heavy Duty and Extra Heavy Duty, can extend up to 60 feet in two sections. Extension ladders that extend up to 72 feet and usually built in 3 sections. Type II, or Medium Duty extension ladders are safe to use up to 48 feet in two sections, and up to 60 feet in three sections. Type III, or Light Duty extension ladders are safe to use up to 32 feet and are made in only two sections. For more about Duty Ratings, see What are Ladder Duty Ratings and Ladder Load Capacities? post.

The measurements you should consider before buying or using an extension ladder are two aspects of ladder length (closed and extended), the distance between rungs, and the width of the base.

Measure Closed Ladder Length
You should consider the measurement of the closed ladder length when measuring the extension ladder for storage or for transportation.

Measure Extended Ladder Length
When measuring the extended ladder length, slide the telescopic fly section(s) to their last position supported by their rung locks. Then measure from end to end to get the overall extended ladder length.

Per OSHA guidelines, the highest level you can safely stand on is the third rung from the top, or that the extended ladder should exceed the roofline by 3 rungs when working with roofs. So measure from the base of the ladder to the third rung, and subtract that from the overall extended ladder length to know the safe extended length to work on.

Measure Distance Between Rungs
OSHA recommends equal spacing between rungs that should be between 10 inches and 14 inches. Most ladder manufacturers adhere to OSHA’s recommendations, but you should still do your due diligence and make sure the extension ladder for sale that you’re considering on buying, does adhere to OSHA’s recommendations.

Measure Base of Ladder
You should consider the measurement of the ladder base primarily for extension ladder for storage or for transportation. There are no safety determinations between ladder length and ladder width at this time. However there are OSHA recommendations on how to safely use extension ladders. See our How to Place Extension Ladders post to learn more.


Buy American Made Ladders
When you’re ready to buy a new step ladder or extension ladder, consider buying an American-made ladder. In 1997, Sunset Ladder and Scaffold began manufacturing safe quality ladders. To this day, Sunset Ladder Brand ladders are the ONLY step ladders and extensions ladders made in America! The Sunset Ladder Brand ladders are sold through different online vendors and retails stores nationally. Sunset Ladder and Scaffold also sell directly to the public. Give them a call today to buy that American-made ladder! Sunset Ladder & Scaffold Website