608
Section 4 Finishing
18.9 Types of Stringers
Treads and risers are supported by stringers
that are solidly fi xed to the wall or framework of
the building. For wide stairs, a third stringer is
installed in the middle to add support.
The simplest type of stringer is the built-
up stringer. It is formed by attaching cleats
on which the tread can rest. Another method
consists of cutting dados into which the tread
will fi t, Figure 18-19. This type is often used
for basement stairs where no riser enclosure is
called for.
Standard cut-out stringers are commonly
constructed for either main or service stairs.
This is the type created in the earlier layout
description. Prefabricated treads and risers are
often used with this type of stringer. An adap-
tation of the cut-out stringer, called semihoused
construction, is shown in Figure 18-20. The
cut-out stringer and backing stringer may be
assembled and then installed as a unit or each
part may be separately installed.
A popular type of stair construction has
a stringer with tapered grooves into which
the treads and risers fi t. It is commonly called
housed construction. Housed stringers can be
purchased completely cut and ready to install.
They can be cut on the job, using an electric
router and template. Wedges with glue applied
are driven into the grooves under the tread
and behind the riser, Figure 18-21. The treads
and risers are joined with rabbeted edges and
grooves or glue blocks. To assemble the stairs,
the housed stringer is spiked to the wall surface
and into the wall frame. The treads and risers
are then set into place. Work is done from the
top downward.
Housed construction produces a stair that
is strong and dust tight. It seldom develops
Backing stringer
Cutout stringer
nailed or screwed
to backing stringer
Figure 18-20. This is a semihoused stringer, an adap-
tation of the cut-out stringer.
Built-up stringer: A stringer to which blocking has
been added to form a base for adding treads and
risers.
Cut-out stringer: A stair stringer into which the rise
and run are cut.
Housed stringer: A stair stringer where the edges of
the steps are covered with a board.
Stringer
Dado
(Depth equal to
1/3 stringer
thickness)
Tread
Figure 18-19. Open riser stairs. Treads are set into
dados cut in the stringer.
Wedges
Taper 3/4"
per 1'
Routed for
treads and
risers
Figure 18-21. In a housed stringer, risers and treads
are let into the stringer. This type of housing is diffi cult
to make.