Stairs are the most common way to provide possibility of moving from one floor to another. One alternative for providing access between floors is the stair lift. It is cheaper than residential elevator.

Naturally, as the complexity of the stairs increases, the installation cost will also increase. Curved rail lifts require a highly detailed on-site survey prior to order.

There are 4 types of stair lifts. First of them is cable drive system. These use a strong steel cable, the kind used in elevators, to advance the passenger. Sometimes it is said that cable drive stairlifts don't have smooth starts and stops but it depends on the model. 

Then there is chain lift. This is usually used heavy duty models and sometimes it can be considerable louder. Then there is a screw lift which uses a screw driven actuator as a lifting mechanism. This mechanism is powered by a rechargeable battery. The fourth option is ‘rack and pinion’ lift (which means gear and teeth). This makes a ride smooth and controlled. Speed can be set by installer, however, the systems must be cleaned and lubricated regularly to prevent damage to the components. Gear teeth can be hazardous, especially to children, but most models have hidden gears.