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3524 Extension Ladders - Keller US
3524 Extension Ladders - Keller US


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3524 24ft Type II Aluminum D-Rung Extension Ladder


SizeStyleMax. Safe Working HeightReach HeightLoad Capacity
24ftMulti Section21ft23ft225lb Load Capacity Commercial Use

The 3524 Aluminum 24ft Extension Ladder has a duty rating of 225 pounds and interlocking side rails. The D rungs are slip resistant. Spring-loaded locks operate smoothly for easy operation. Shoes rest flat or are held in spur position with swiveling shoes feature. Mar-resistant end caps help protect the surface ladder is leaning against. Exclusive 3-piece rung-to-rail connection means twist-proof performance every time.


  • Exclusive 3-piece rung-to-rail connection means twist-proof performance
  • 1-1/2in slip-resistant D-rung steps
  • Durable extruded rung locks are spring loaded to operate smoothly
  • Mar-resistant end caps
  • Smooth operating pulley with polypropylene rope
  • Heavy duty modified I-beam side rails
  • Durable shoe rests flat on slip resistent pad or is heldin spur position with swiveling shoes feature


FeatureSize / Details
Max. Safe Working Height21ft
Max. Open Extended Length21ft
StyleMulti Section
Load Capacity225lb Load Capacity Commercial Use
Duty RatingType II Duty Rating
Approx. Closed Length144in
Approx. Cu. Ft. Per Unit8.3
Approx. Product Weight (lb)32.7
Approx. Shipping Weight (lb)32.7
Base Width18-1/4in
CertificationsANSI A14.2 (2007), OSHA
Flange Dimension15/16in
Max. Load225lb
Number of Sections2
Reach Height23ft
Section x Rungs2 x 12
Rails Dimension3in
Rung Dimension14-3/4in x 1-1/2in
Rung TypeD-Rung

Package Contents

Part NumberQtyDescription



Additional 3500 Series Models

Model No.SizeMax. Safe Working HeightMax. Open Extended LengthStyleApprox. Closed LengthApprox. Product Weight (lb)
352020ft17ft17ftMulti Section120in26.2
352424ft21ft21ftMulti Section144in32.7
352828ft25ft25ftMulti Section168in42
353232ft29ft29ftMulti Section192in53.3
353636ft32ft32ftMulti Section216in74.4
354040ft35ft35ftMulti Section240in82.4

Different types of ladders are designed to keep you safe and productive when climbing or standing. Using the wrong style of ladder or simply ignoring the limitations of climbing equipment can result in a fall or serious injury.
Height reach Height is referring to the actual ladder height. Extension ladders should be 7 to 10 feet longer than the highest support or contact point, which may be the wall or roof line. The highest standing level is four rungs down from the top. The highest permitted standing level on a stepladder is two steps down from the top.

Reach height is the maximum reach assuming a 5’6” person with a vertical 12” reach.
Ladders are designed to safely hold up to a specific amount of weight. The Werner Performance System defines five different capacities using a color and star rating system. The Duty Rating is defined as the maximum safe load capacity of the ladder. A person’s fully clothed weight plus the weight of any tools and materials that are carried onto the ladder must be less than the load capacity.

Performance system
Werner offers ladder made from fiberglass and aluminum. Each material has characteristics which make it best for certain applications, or one material may simply fit the personal preferences of the user. For example, if working around electricity users should select fiberglass products due to their non-conductive side rails.