Fig. 1 shows the plan of a dog-legged stair. The first thing to be done
is to take off the sizes on a rod. First take the rod, marked Fig. 3.
Cut this rod in between the brick walls, taking care to try it between
the walls where the two flights come together at risers 12 and 13.
Set off on each end of this rod the thickness of plaster; now set off
the face of wall strings so that they will be flush with the face of
the skirting. Then set back from face of the string half an inch, the
depth of the housing, this will be the end of the treads and risers.
Next set off the centre of the rod, draw the newel and string on the
rod, half their thicknesses on each side of the centre line. Then set
back towards the centre from each face of the centre string, half an
inch, the depth of the housing. This gives the length of the treads
and risers; and if ordinary care is taken in setting out this rod, and
working to it, no mistake can be made.
The height rod is seen at Fig. 4. Set off on this rod the height from
the top of the bottom floor to the top of the top floor. Now divide
this height into as many parts as there are to be risers, and the
distance from one division to another represents the height from the
top of one tread to the top of the next. The number of risers and the
height of them must be regulated by circumstances. A few hints only can
be thrown out here. The rise should not be less than 6 inches or more
than 7¼ inches, while the going and the rise added together should not
be less than 16½ inches or more than 18 inches. Thus, it will be seen,
the going should be regulated by the rise. For instance, say the rise
is 7¼ inches, then the going should not exceed 10¾ inches; this would
make the going and rise added together 18 inches. Now, the stairs
would be easier if the going was only 9¾, as this would make the two 17
inches, which is a better average than 18 inches. These remarks are not
laid down as a fixed and unaltered rule, but are intended as a guide in
the setting out of stairs of any description. Mark off on the height
rod the floors, joist and ceiling of both landings, as shown at Fig. 4.
In putting in the landing, use the height rod to get the height of the
joist, but care must be taken to take the height from the proper floor
level, in case the floor is not down.
Fig. 5 shows the going rod. Put one end of this rod against the back
wall, and mark on to it all doorways, trimmer joists, &c. The width
of landing and the going must be regulated by circumstances, but the
risers, newels and all joists must be marked on to the rod as shown. In
putting in these trimmers it is always as well to square them, that is,
put them in square to the side walls, then should the back wall be out
of square the difference will be in the landing.
Fig. 6 shows the pitch board. These are best made of zinc. Make the
rise equal the height of one rise on the height rod, and the going
equal the going of one step on the going rod.
Fig. 7 shows the construction of one step. A plan and elevation of
the stairs should always be made to a scale of, say, ¾ of an inch to
the foot, or, if possible, to 1½ inch to the foot, and all openings,
headroom, &c., should be shown. The line H H, Fig. 2, is drawn parallel
to the line of nosings on the bottom flight, and at a height above them
of 7 feet. Then the bottom edge of the top landing must be kept above
this line to give sufficient headroom. The setting out of the strings
and glueing up of the steps, &c., will be seen on Plate III.
[Illustration: PLATE 3.]