Some designs for oak staircases include straight, L-shape, U-shape, curved and spiral. The straight variety includes a simple oak straight staircase, with or without a closed string. The string is the piece of wood that closes the gap between one step and the next. Depending on if the staircase juts up against a wall or is free-standing, it may have one or two railings. More elaborate straight designs include balustrades with decorative newels or end posts.
L-shaped or U-shaped stairs are often used to conserve space and to make climbing easier. These are actually two flights of stairs connected by a landing, which provides a place to stop and rest if needed. These types of stairs almost always have substantial handrails or balustrades, especially in office situations. Some modern designs use oak frames for the balustrades and fill in the side panels with glass.
Curved oak staircases add graceful looks to rooms. They often are used to build staircases in places where there is not enough space for landings but straight stairs would be too steep. Elaborate curved staircases are often features of Southern mansions, as seen in the movie "Gone with the Wind."
Spiral staircases are similar to curved ones, but they go straight up from one floor to the next. They are built around single center posts, with the steps angling as they go up and around the posts. Sometimes the posts are used as handrails, but curved balustrades may be placed from top to bottom.