There are several factors to consider before investing in aluminium extension ladders. First you must choose from the two types – solid beam and truss construction.
Solid beam aluminium ladders
Because they use a solid side rail beam with aluminium rungs, solid beam aluminium ladders tend to be extremely sturdy.
The aluminium rungs are either connected to the side rails using a welded joint between the rung and side rails, or through use of an expansion plug pinching each rung to the side rails.
The plug method makes rung replacement easy, providing an easy method to tighten loosened rungs subjected to wear or tear.
By contrast, the welding method may require re-welding when replacement is necessary. Loose rungs are never a problem though.
When re-welding is required, the entire section of ladder may need to be replaced.
Truss construction aluminium ladders
A truss construction aluminium ladder is similar to the construction of a wooden one with a single, but important, difference – it is connected using rivets instead of glue and bolts.
Rungs are either welded or expansion plugged, supported by the top and bottom rails of the truss side beams.
This allows for both greater side beam heights and the capacity to carry a heavier load without the need for huge side rails, which add to the overall weight of the ladder.
On extension ladders, with two or more sections, the top sections are usually operated by a cable assembly, which is used by raising the second section with the rope.
This is not possible for many wooden ladders as they are too heavy. The rope or cable must have a slight tension on it when all sections are fully closed or at rest in its bedded position.
If the cable is too tight or too loose the sections will not lock at the same time. Since this is unsafe, adjustments will be necessary. You must also check the cable for excessive wear and tear and be sure it has the proper adjustment.
Take a look at all the aluminium ladders available at Browns Ladders.