U Shaped stairs are basically 2 parallel flights of straight stairs joined by by a landing that requires 180 degree turn in the walk line. If a third flight is inserted into the middle of the stairs, it would become a double L stair (or quarter landing).
Advantages of U shaped Stairs:
- U shaped stairs can be easier to fit into an architectural plan.
- They offer some architectural interest.
- The landing(s) can offer a resting point part way up the stairs.
Disadvantages of U shaped Stairs:
- These types of stairs are a bit more difficult to build.
