Stairs add to the elegance of any room. They are a focal point in design. Elegant stairs can give a home personality. A beautiful stairwell not only provides functionality, it also adds character.
However, many people might not even realize the complexity involved in building any stair system. Even though we climb or descend thousands of stairs every year.
First, stairs should be comfortable to climb. They must be easy on your back upon ascent and just as easy and safe on your body when you descend. There are also approximate and similar height in the rise for every stair and there are similar sizes even for the step itself.
A stairs rise (or the distance in height between each step), is designed that way for a reason. The rise is usually between 7 - 8 inches. The step, which is also known as the thread, also has approximate measurements for a foot to feel comfortable. The thread is usually between 10 - 12 inches. Anything under or over these measurements might be might not feel right to most people. That's not saying that there aren't plenty of staircases around that do not follow these measurements and they function just fine. But these measurements are the standard in the trades because it was determined over time that this was the most comfortable for the average body.
Here are some common terminology and definitions.
A straight stairway with tiled treads, a double railing and two landings.
Commuter bottleneck on a staircase in a New York City subway station.The step is composed of the tread and riser.
tread - The part of the step that is stepped on. It is constructed to the same specifications (thickness) as any other flooring. The tread "length" is measured from the outer edge of the step to the vertical "riser" between steps.
riser - The vertical portion of the step between steps. This may be missing for an "open" stair effect.
nosing - An edge part of the tread that protrudes from the riser beneath. If it is present, this means that horizontally, the total "run" length of the stairs is not simply the sum of the tread lengths, the treads actually overlap each other slightly
bullnose - Where stairs are open on one or both sides, the first step above the lower floor may be wider than the other steps and rounded. The rounded portion of the step is called a "bullnose". The pickets typically form a semi-circle around the circumference of the bullnose and the handrail has a horizontal spiral called a "volute". Besides the cosmetic appeal, bullnoses allow the pickets to form a wider, more stable base for the end of the handrail. Handrails that simply end at a post at the foot of the stairs are usually unstable, even with a thick post. A double bullnose can be used when both sides of the stairs are open.
winders - Winders are steps that are narrower on one side than the other. They are used to change the direction of the stairs without landings. A series of winders form a circular or spiral stairway. When three steps are used to turn a 90° corner, the middle step is called a kite winder due to its similarity to a diamond-shaped kite.
stringer, stringer board or sometimes just string - The structural member that supports the treads. There are typically two stringers, one on either side of the stairs; though the treads may be supported many other ways. The stringers are notched so that the risers and treads fit into them. Stringers on open-sided stairs are often open themselves so that the treads are visible from the side. Such stringers are called "cut" stringers. Stringers on a closed side of the stairs are closed, with the support for the treads routed into the stringer.
trim - Trim (e.g. quarter-round or baseboard trim) is normally applied where walls meet floors. Within a flight of stairs there is no trim as the trim thickness will significantly eat into the tread width. Shoe moulding may be used between the lower floor and the first riser. Trimming a bullnose is a special challenge as the last riser above the lower floor is rounded. Today, special flexible, plastic trim is available for this purpose. Scotia is concave moulding that is underneath the nosing between the riser and the tread above it.