Modern ladders are generally constructed from three materials: wood, aluminum and fiberglass. While each type of ladder has its benefits and trade-offs, a fiberglass ladder does have some advantages to consider.
Perhaps the biggest advantage a fiberglass ladder has over its aluminum counterpart is resistance to electricity. Even though a fiberglass ladder may use aluminum rungs, the rungs themselves are kept separate. Fiberglass does not conduct electricity, so it is much safer to use around power lines than highly-conductive aluminum.
A fiberglass ladder is also constructed from man-made material, which gives it an advantage over wooden ladders. Natural materials like wood can have significant variations in quality, so a weaker wooden ladder rung or support beam could fail without warning. Fiberglass beams are uniform and inherently strong. Aluminum may be more consistent than wood, but different manufacturers use different grades of aluminum. A cheaper aluminum ladder could bend under a load.
Many handymen and construction workers find that a fiberglass ladder is more resistant to bad weather conditions. Wood ladders can eventually rot after a few cycles of wet and dry exposure. A fiberglass ladder does not absorb moisture or weaken significantly in the sun.
A fiberglass ladder is also flame resistant, making it ideal for firefighters scaling smaller buildings. Fiberglass will scorch and briefly flame under a direct heat source, but will self-extinguish after that source is removed. Aluminum ladders may also be more flame resistant than wood, but they can conduct electricity transferred by water. The main drawback of a fiberglass ladder is weight versus size. Fiberglass is heavier than either wood or aluminum, so it cannot be used in long extension ladders.
A fiberglass ladder may not be completely problem-free, but it does offer a more durable alternative to natural wood and a safer alternative to conductive aluminum. If height or weight is a serious consideration, then fiberglass may not be preferable to wood or aluminum. But by and large homeowners do not need extremely tall ladders to perform most chores, so the overall shelf life and inherent strength of a fiberglass ladder may be ideal.