Difference between stringer and bowstring.

The stringer and bowstring are the main structural details of many ladders. Their function is the same: to support the steps and other elements of the structure. What is the difference between a stringer and a bowstring? Information on this is set out below.

How the details look

Parts of the ladder in question are inherently inclined beams. In the above image, these supporting elements are adjacent to the edges of the steps:


As you can see, one part has a jagged shape in the upper part, and the second has smooth contour on both sides. But besides visual, there are other signs that make up the difference between a stringer and a bowstring. And the first, most important point is the way of fastening the steps. In the case of a kosour, they are laid on the horizontal of the teeth, leaving the ends visible. In the bowstring, grooves are made from the inside, where the ends of numerous transverse strips are placed. Sometimes the steps are not held in the slots, but on the bars nailed to the beam.

There can be a different number of stringers in the stairs. Most often there are two of them. But in some designs, only one such element is provided. In addition, there are structures with a central stringer and two lateral ones. As a rule, these are stairs with a decent flight width. The bowstring, in turn, is used only in duplicate. In this case, the beams are located exclusively on the sides.

The next point concerns the installation of the enclosing elements on the stairs. It is worth noting here that the kosour cannot directly support the balusters. Their bottom with such a device is on the steps themselves. Meanwhile, enclosing parts can be installed on the bowstring, but then it must have impressive thickness parameters. Otherwise, an overhead strip of the required width is attached to the beam of the named variety, and the columns are attached to it, leaving the desired gap between them.

It must be said that stairs with load-bearing elements of both types occupy a different area of ​​space. What is the difference between a stringer and a bowstring in this regard? It consists in the fact that the version of the structure with a stringer with one length of steps will be more compact. Such a ladder looks a little simpler, but its installation in small rooms is more expedient. Bowstrings also take up some space on the sides. The staircase with them looks richer and more elegant. A similar design is better suited for large spaces.


Kosour Bowstring
Serrated shapeSmooth contours
Positions under the stepsGrips the steps from the sides
Not always in double quantitySuch beams are used only in pairs
Balusters on the stepsThe guardrails rest on the bowstring or a bar nailed to it
A ladder with beams of this type is more compactThe whole structure takes up more space
The structure with a stringer looks simplerGives the staircase a more dramatic look