Manual of Purpose-Made Woodworking Joinery

104 Designing and making stairs to current building regulations

Stairwell wall surfaces

When measuring pre- formed stairwells to confirm

the height, length and width for the staircase to be

made or ordered, also check that the blockwork or

brickwork surfaces of the stairwell are straight, plumb,

square- cornered and without any mid- area irregulari-

ties. Check also whether the bare stairwell- surfaces are

to be plastered with float- render- and- set (skimmed)

plaster or dry- lined with so- called ‘dot- and- dab’ plas-

terboard. This is most important because wall- strings

were traditionally fixed directly to the structural wall

before plastering, but such fixings nowadays make it

more difficult for dry- lining operations – and there is

evidence that stairwells and stair- walls are being dry-

lined before the stairs are fitted and fixed.

12¾ risers produces 12¾ goings of, say, 220mm.
Therefore 12.75 × 220mm = 2. 805m as the measure-
ment of the stairwell opening from top- riser face to
the bulkhead position.

Allowances for half- turn landings

Figures 6.30(a)(b)(c): The traditional half- turn stair
with a half- landing in its mid- rise area was known
as a ‘dog- legged stair’. This was because there was no
space between the two flights and the tenons of the
outer string (the inclined board, housing the ends
of the steps) of each flight were housed in the same
newel post, giving the visual effect of a continuous
dog- leg shaped outer string.

Calculating the

position of the

bulkhead trimmer

from known step-sizes

Bulkhead

trimmer

255

12¾ risers

at 180–255 mm

= 2.040 m

Headroom

12¾

12¾ Goings at 220 mm = 2.805 m

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Figure 6.29 (a) A simple calculation to

establish the bulkhead- position for Headroom, if

forming the trimmed stairwell- opening.

*

Allow for nosing +

riser thickness +

10 to 18mm tolerance

Add allowances*

Trimmer to trimmer

(2.872 m)

12¾ goings (2.805 m)

*

Allow for apron

lining + grounds

* *

Figure 6.29 (b) Graphic illustration of the various allowances to be taken into account between the landing trimmer- or
trimming- joists to establish the bulkhead position.