Extension Ladder

Extension ladders are sized by nominal extended length in feet. The class breaks into bands: up to 16 ft for single-storey eave and low roof work; 16–20 ft for gutters, second-storey windows and standard residential roofs; 20–26 ft for two-and-a-half-storey commercial soffits and taller residential roofs; 26–32 ft for three-storey commercial walls, steep roofs and chimney work; and 32+ ft for three-plus-storey access. Sizing starts from the height to reach, then adds the losses: required section overlap and the 4:1 setup angle both eat into reach, and access above a roofline needs the ladder extending about 3 ft past the support point. After length, duty rating is matched to the combined weight of worker, tools and materials.

• Roofing, gutter and eavestrough access
• Exterior siding, trim and painting
• Window installation and washing on multi-storey buildings
• Utility, cable and signage work at height
• Tree trimming near structures
• General exterior repair and inspection

• Set the base one unit out for every four units of working height — the 4:1 rule in OSHA 29 CFR 1926.1053 — and extend at least 3 ft above a landing used for access.
• Duty ratings under ANSI ASC A14 run from 200 lb Type III to 375 lb Type IAA; the rating covers worker plus tools.
• Aluminum ladders are prohibited near energized overhead lines and electrical equipment — fiberglass is the non-conductive option.
• Maintain three points of contact, keep the body centered between the rails, and tie off the top on long setups or in wind.
• Inspect rung locks, rope and feet before each use; a worn rung lock is how fly sections fail suddenly.

ANSI ASC · A14.2

Safety standard for portable metal ladders, including duty rating types.

ANSI ASC · A14.5

Safety standard for portable reinforced-plastic (fiberglass) ladders.

OSHA · 29 CFR 1926.1053

Construction ladder rule covering setup angle, extension above landings and use practices.