Spiral staircase is the most interesting design that a staircase can get. There are so many variations and types of spiral staircases and they all are lovely and they add extremely good quality to the interior where are installed. There are Continuous stairs (Circular stairs, Spiral stairs and Helical stairs) and Turning stairs which are sub classified as: Quarter turn stairs (Newel quarter turn stairs, Geometrical quarter turn stairs); Half turn stairs (dog legged stairs, Open newel half turn stair, Geometrical half turn stairs); Three ? quarter turn stairs and Bifurcated stairs.  
The images are clearly showing the installation process of several of them in accessible and understandable way.

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