Searching for a ladder? Here’s some info to help you find the right one. For many tasks, the rigid ladder is the type often used. Rigid ladders come in many varieties – fixed, extension, step, platform step, and roof. The fixed ladder is the most basic, and has no moving parts. Extension ladders are composed of two ladders where one nests in the other for easy storage. Step ladders are always joined by a hinge at the top of its inverted V form. The one with a platform is naturally called the platform step ladder. If you need to climb up the roof or do some outdoor house painting, you need a roof ladder, which has a hook at the top, for easy latching on the roof. Aluminium is the preferred material for ladders, except those used for electrical work, for which fibreglass ladders are used.