Manual of Purpose-Made Woodworking Joinery

114 Designing and making stairs to current building regulations

blind- mortises in the newel posts should be marked.

This can be triggered off by laying each newel tightly

against the shoulders of the string- tenons and haunch-

ing, then by pencilling their outline onto the newels.

These outlines can then be squared across the inner,

adjacent face of the newel to give the mortise and

haunch positions. This technique can also be applied to

the handrail- tenons (See Figures 6.43c and d).

After the newels have been mortised, all tenons

should be tried for fit. At this stage, the draw-

bored holes in the newels, strings and handrails can

be done – rather than leaving this task to the site

carpenter – and the drawn- up quality of the shoulder-

fits can be checked by driving in 12mm Ø tapered

metal draw- bore pins, hooked at their ends for easy

removal (as shown in Chapter 3).

Figure 6.43 A, B, C and D illustrate the marking out

on the four unfolded faces of a bottom newel post to

receive a protruding step housed into its front face. As

shown below FFL, an allowance is normally given at

the bottom of newels to cater for the various methods

of site- fixing. The tops of the newels may or may not

be finished, depending on whether they are finished in

themselves, or are to have separate caps fitted on site.

Riser- and tread- housings into strings are com-

monly 12mm deep, but because the risers into

newel- housings are screwed through the risers’

back- side – and not wedged – the housings in the

newels should be 18mm deep.

Stair assembly

Figures 6.44(a)(b)(c): Assembling a stair flight

has always presented a problem in the gluing- up

There are two reasons for dowelling tenons in stair
work. 1) The tenons are not wedged and may become
loose if shrinkage occurs and 2) by draw- bored dowel-
ling (offsetting the drilled dowel- hole by about 2mm
in the tenon only, towards the shoulder of the newel
post), the shoulders of the joints can be pulled up
when the blunt, pencil- like sharpened dowel is driven
in. It also has to be understood that a rhomboidal-
shaped frame of two parallel newel posts and a hand-
rail parallel to the outer string, cannot be cramped
together (especially on site) in the normal way that a
square- shaped frame is cramped.
The traditional rule for draw- boring is that the
centre of the positioned dowel should be twice its diam-
eter from the shoulder of the joint – as illustrated above.

Marking out handrails and newel posts

Figure 6.43: Before assembling the stair flight, the
shoulders of the handrail tenons are best marked from
the shoulders of the outer- string tenons, by laying
and cramping the handrail along the string’s top edge.
Also before stair- assembly, the step- housings and

A

A

Part Plan

B

FFL

900

mm

B

C

C

D

D

Figure 6.43 A, B, C, D: Elevation and part plan of
unfolded newel- post faces.

Minimum BSI

sizes

230 mm

maximum

centres for

screws

(BS 585)

Two blocks per

step for stairs

up to 900 mm wide

38

38 75

Figure 6.44 (a) The tongued riser is glued to the tread

groove, then at least two blocks are glued and rubbed

into position – and pinned, if necessary, to achieve a

true right- angle after checking the inner L- shape with a try

square.