Stairs provide a means to move from one level to another safely and easily. There are many types of stairs, and as a matter of precaution, they must have side rails that can assist in the climbing activity. All stairs will have treads and risers that must be comfortable and safe to use. 12-inch treads and 6-inch to 8-inch risers are a standard that is accepted in most building codes.
The most common type of stairs is one that has a single flight of stairs that connects the lower level and the upper level. These straight stairs are easy to build. They are useful where the number of risers is less than 16 or the height to be climbed is less than 12 feet. You can have a straight stir with a landing when heights exceed 12 feet. This will increase the area that is required by the stairs, and may not be suitable for small rooms. Quarter turn stairs or L shaped stairs will conveniently turn the direction of the stairs at a landing. They are visually more interesting and create a visual barrier that can add to privacy concerns. They can easily be located in the corner of a room. They are however difficult to built and landings may require proper supports. Handrails have to be more carefully designed and constructed. Winder stairs have triangular steps that allow the stairs to change the direction. They make staircases more compact, though they are not easy to use, as care has to be taken, due to the change in tread widths. Handrails on these stairs are also difficult to install.
Another type of stairs that is commonly used in large buildings are U shaped stairs. They are easy to fit into most architectural plans and will have two landings or a large landing that allows the stairs to completely change direction. They are difficult to build and must have adequate support structures. Spiral staircases make for a type of stairs that are very compact and occupy the least space. They will have stair treads going around a central pole, while every riser takes you up a certain height. They can be architecturally attractive, though their handrailings are difficult to construct. The central pole is all the support that is required and all loads are transmitted directly downwards. They are not easy to navigate, and thus not allowed as a primary access for buildings.
Other types of stairs are curved stairs and ladders. While curved staircases are architecturally very pleasing and commanding, ladders are the most difficult to climb. Information supplied by Stellar Stairs.