This section is from the book "Notes On Building Construction", by Henry Fidler. Also available from Amazon: Notes on building construction.
In laying out winders it should be remembered that when a person on the stairs is using the handrail he places his foot on the steps about 18 inches in from the balusters; each winder should, therefore, at a distance of 18 inches in from the handrail, have a width equal to that of the treads of the fliers,2 otherwise (the fliers being properly proportioned) the winders will at this point be too narrow in proportion to their height.
This cannot always be accomplished in dog-legged stairs; for instance, if it were absolutely necessary to introduce three winders into a quarter-space of the landing of the stair shown in Fig. 200, these could only have a width of 9 3/7 inches at 18 inches in from the handrail, whereas the fliers have a width of 10 inches.
For a similar reason four winders should be avoided as much as possible in dog-legged stairs. It will be seen in Fig. 226 that the width of treads at 18 inches from the newel can never be more than 7 inches. Thus the treads of the winders must be narrower than those of the fliers, and therefore inconvenient.
Four winders are, however, very frequently introduced as shown, for they are often absolutely necessary in order to gain the height required within the space available.
1 If the height to be gained were the same as in Fig. 201, viz. 10 feet 10 inches, the rise for the steps would be 130/19 = 6 16/19 inches.
2 If the staircase be narrower than 3 feet, the width of treads should, of course, be kid off along the centre of the winders. It is sometimes considered better to have three or even five winders than four ; because when there are four there is a riser of need less length running into the angle of the staircase (see Fig. 226).
As it is difficult to follow these rules under all circumstances, they are often infringed, and in common staircases it is considered quite sufficient if there is a proper width of tread in the centre of the length of the winders.
In consequence of the inner ends of winders having such narrow treads, while their height is the same as that of the other steps, the inclination of the line of nosings of the winders is much steeper than that of the fliers - which gives a sudden and ungraceful change to the inclination of the handrail above them.
To avoid this, and in order to gain some additional width at the inner ends of the winders, they are in some cases made to "dance," - that is, they are drawn so as not to converge to the same point, but so that each is directed upon a different point - found in a manner too intricate to be entered upon in this Course.
Fig. 233. Scale, ¼ inch = l foot.
In Fig. 233 the first four and the last four steps are parallel - but the remainder are "balanced" or "dance," as above described.