Manual of Purpose-Made Woodworking Joinery

Limiting factors 93

compared with Figure 6.2(b). Although, a single step

positioned at the head of a stair can be dangerous, as it

is not always noticed.

LIMITING FACTORS

There are many limiting factors to contend with in

stair design and in site- access for the assembled flights.

These include: 1) clashing door- and/or window-

positions; 2) structural intrusion of piers and offset

walls; 3) serving split (mezzanine) floors with incon-

sistent storey heights; 4) striking a regulatory balance

between shallow and steep stair pitches; both of which

are tiring to ascend and the latter type being dangerous

to descend; 5) achieving sufficient regulatory head-

room – defined in Figures 6.2(a) and (c) – so as not

to cause a tall person to stoop or suffer head injury;

and 6) achieving good access and adequate ‘clearance’

for the movement and manoeuvrability of furniture,

etc, up and down stairs. Where access to a stairwell is

restricted and/or awkward – which is not unusual when

replacement or additional stairs are being installed in a

property – the makers and fixers of the stairs often have

to complete the assembly of the separate made- up steps

and the strings by improvisation on site.

Stair design, then, is essentially an integral part of

the whole design of a building and perhaps only con-

cerns the architect – although to implement the archi-

tect’s design from small- scaled drawings (or take on

the role as designer and maker) means we need at least

as much technical knowledge as the designer. Also, we

need a good understanding of the Building Regulations.

Figures 6.2(a)(b)(c)(d): These plan- and elevation-
diagrams outline the four most common stair arrange-
ments in use. Although variations to these basic
designs can be made, they serve to compare the effect
on available floor space – and show where the ‘head-
room’ (HR) regulation applies – and highlights the
application of the headroom measurement for posi-
tioning the trimmed stairwell- opening.

ADDITIONAL CHANGE

Figure 6.3: In the diagrams in Figures 6.2(a), (b) and
(d), another change in direction could be achieved by
making allowance for a quarter- turn landing at the
top of each flight. This would reduce the total going by
one step – if required – as indicated in Figure 6.3 and

Figure 6.2 (c) Half- turn stair via a half- turn landing (d) Quarter- turn stair via four tapered steps. Note that – at the scaled-
design stage – the minimum legal headroom has been worked out to be above the third riser (*).

* POSITION OF BULKHEAD TRIMMER

HR

DOWN

HR

UP

*

*

1

2

3

(^567891011121314154)
1
1514131211109
2345678
(c) (d)
TOTAL GOING USED IN FIGURE 6.2(b)
DOWN
15
1413121110987654
3
2
1
Figure 6.3 A quarter- turn landing added at the top
reduces the total going by one step and changes the
designation to a half- turn stair.