Manual of Purpose-Made Woodworking Joinery

92 Designing and making stairs to current building regulations

Figure 6.1(c): The above concept of relating a step
to a triangle can also be applied to a multiple of steps,
as illustrated above, whereby the ‘total going’ of all
the steps (equally divided horizontally between the
face of the top step and the face of the bottom step)
and – likewise – the ‘total rise’ of all the steps (equally
divided between the lower- and the upper- floor
levels), forms a pitch angle according to the ratio of
the total going (TG) related to the total rise (TR).
Figure 6.1(d): In considering an acceptable pitch-
angle, the total rise is of course a constant, but as
shown by comparing Figures 6.1(c) and 6.1(d), an
adjustment to the total going alters the angle of pitch.
This is an important factor in stair design, especially
when trying to fit a staircase into a small space where
there is a limited TG.
As seen in Figures 6.1(c) and (d) above, TR (total

Figure 6.1 (d) Although the scaled total- rise and the
number of divisions at 6.1(c) is equal to the illustration at
6.1(d), it can be seen how an increased going of each
step alters the pitch angle. Figure 6.1(c) has a 40° pitch;
6.1(d) has 29°.

X

TG

4

TR

5

(d)

Figure 6.2 (a) Straight- flight stair; (b) Quarter- turn stair via a quarter- turn landing.

rise) is divided by five, unlike TG (total going) which is

divided by four. This is because the top steps – marked

X in each Figure – are in fact part of the landing and

therefore are not included in the horizontal division.

As the top surface of a step is called a ‘tread’ and the

vertical face is called a ‘riser’, as a rule it can be said that

in any single flight of stairs, there must always be one less

tread than risers. When initially designing a staircase

and calculating how many steps can be used to meet

the various regulations, this basic rule ensures a correct

trial- and- error division of TR related to TG.

Although straight flights of stairs are quite common,

they are not universally regarded as being very attractive

and they are not always possible with a restricted going,

i.e. a limited stairwell length. For these reasons, changes

in the direction of the stair are often made.

DIRECTIONAL CHANGES

If you think of directional changes – in any stair

design – as they would relate to a spiral staircase

having a complete turn of 360°, then it can be readily

seen that a quarter- turn stair changes direction by

90° and a half- turn stair changes direction by 180°.

Although three- quarter- turn stairs, changing direc-

tion by 270°, can be found in older- style properties,

they are not seen nowadays in modern dwelling

houses. Apart from straight flights, quarter- turn and

half- turn are the two most common types of turning

stairs – and are turned by introducing either a quar-

ter- or half- turn landing (an intermediary platform),

or tapered (winding) steps. With tapered steps (the

modern term), because they are considered to be

potentially more dangerous, it is safer to keep them at

or near the bottom of a staircase, if possible.

15 14 13 12 1110 9 8 7 6 5 4

3

2

1

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HEADROOM* HR*

UP

DOWN

* Note: Headroom height determines

the position of the bulkhead trimmer

(a) (b)