Chapter 18 Stair Construction
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18.8 Treads and Risers
The thickness of a main stair tread is gener-
ally 1 1/6″ or 1 1/8″. Hardwood or softwoods
may be used. FHA requires that stair treads
be hardwood, vertical-grain softwoods, or fl at-
grain softwoods covered with a suitable fi nish
fl ooring material.
Lumber for risers is usually 3/4″ thick and
should match the tread material. This is espe-
cially important when the stairs are not covered.
In most construction, the riser drops behind the
tread, making it possible to reinforce the joint
with nails or screws driven from the back side
of the stairs. Figure 18-17 shows basic types of
riser designs. A sloping riser is sometimes used
in concrete steps since it provides an easy way
to form a nosing.
Where the top edge of the riser meets
the tread, glue blocks are sometimes used. A
rabbeted edge of the riser may fi t into a groove
in the tread. A rabbet and groove joint may also
be used where the back edge of the tread meets
the riser.
Stair treads must have a nosing. This is
the part of the tread that overhangs the riser.
Nosings serve the same purpose as toe space
Total run: The horizontal distance occupied by the
stairs; measured from the foot of the stairs to a point
directly beneath where the stairs rest on a fl oor or
landing above.
Nosing: The part of a stair tread that projects beyond
the riser.
along the fl oor line of kitchen cabinets. They
provide toe room. The width of the tread nosing
may vary from about 1″–1 1/2″. It should seldom
be greater than 1 3/4″. In general, as the tread
width is increased, the nosing can be decreased.
Figure 18-18 illustrates a number of nosing
forms. Cove molding may be used under the
nosing to cover the joint between riser and tread
and conceal nails used to attach the riser to the
stringer or carriage.
Basement stairs may be constructed with an
open riser (no riser board installed). Sometimes
an open riser design is built into a main stair
to provide a special effect. Various methods
of support or suspension may be used. Often
custom-made metal brackets or other devices
are needed.
Rabbet and
groove
Vertical Sloping Open
Overlap
(nosing)
Figure 18-17. Basic stair riser shapes. For the open riser, the tread should overlap the riser at least 2″.
Cove
(optional)
Nosing designs
Tread
Riser
1 1/8" to 1 1/2" nosing
Figure 18-18. Common tread nosings.