614
Section 4 Finishing
especially designed for stair work is illustrated
in Figure 18-30.
18.13 Spiral Stairways
Metal spiral stairways eliminate framing
and save space. See Figure 18-31. Units are avail-
able in aluminum or steel in a variety of designs
to fi t requirements up to 30 steps and heights up
to 22′-6″. Use of spiral stairs is often restricted
by building codes. Some codes permit use of a
spiral stairway for exits in private dwellings or
Wall rail
bracket
Handrail bolt
Figure 18-30. Hardware for stair rails. The handrail
bolt is concealed in the center of a joint. The nut is
accessible from below and can be adjusted with a
screwdriver or a hammer and nail set.
Center balusters
available for
all diameters
37 1/8" long
1/4 - 20 x 3/4"
thread cutting
screw drill
7/32" hole
Center column
4" O.D. x .125 or .156 wall
Spacer rings 4 1/2" O.D. x 1/2" to 1" long
the height of the spacer rings (1/2" x 1")
is determined by the floor to floor height
which dictates the rise factor
Bottom starter ring
4 1/2" O.D. x 2 1/4"
or 1 1/2" use 1 1/2"
with 3/4" wood tread
covers. All other
applications use
the 2 1/4" ring.
Lag screw
3/8 x 2"
lead shield
Drill 5/8" hole
1 3/4" deep
Bottom baluster is 40 1/8" long
1/4" x 1 1/4" carriage bolt & nut
drill 1/4" hole in baluster
Second baluster
is 48 1/8" long
All other balusters are
41 1/8" long with the
bottom hole pre-punched
8/32" x 7/16"
bolts & nuts
Aluminum handrail
Vinyl rail cover
Splice plate
Platform and top anchor cap
#14 x 1 1/4" screws
8/32" x 7/16"
bolts & nuts
Handrail
end cap
Figure 18-31. Assembly drawing of a spiral stairway.