Installing Manufactured Stairs, continued
After everything's fastened, the installer adds reinforcing
glue blocks on the back sides of all the tread, riser, and
stringer joints (Figure 5).
5. Glue blocks are stapled and glued to every
joint from the underside (left) to add solidity and
prevent squeaks. Next, cove molding is finish nailed
beneath each tread nosing (right).
The bullnose riser assembly is a good example of the blend
of efficiency and quality. The process involves routing and
kerfing out a strip of 1-inch finish plywood for the riser,
bending it around a radius form, gluing and nailing the whole
assembly in place, trimming the butt end to length, and
attaching the finished riser to the staircase (Figure 6). It
probably takes less time for a worker to do this in the shop
than it would take a carpenter on site to set up his power
6. Kerfed plywood is bent around a pre-made form
to make a bullnose riser.
You can figure on two people taking part of a morning just to
install the stairs (Figure 7). Railings might take the whole
afternoon. If you've got a bigger set of stairs, like a full
90-degree radius stair, you'll need some extra labor on hand to
help with the lifting. And, of course, expect the fine work to
7. Two men can easily carry and place a typical
straight staircase (left). For large or complicated
staircases, you may need more manpower. The installer
pins the lower staircase section in place, using a
scrap of landing tread to determine the correct height
for the top edge of the riser (right). He places the
first screw where cove molding will cover it
By the way, if the stairs are big, remember to leave a way
into the building. I forgot that once, and we had to cut a
large curved stair in two pieces just to fit it through the
Before you place stairs, a last check of openings and of
plumb and level is a good idea. On the job featured here, the
installer was confused for a minute because someone had removed
a post under the floor to pour the basement slab. Every time
the installer tried to shim up the landing, the floor below
dropped instead -- until it dawned on him that he needed a
temporary post in the basement.
But if the framing is on the money, as it should be,
installing a staircase is like installing one cabinet: Get it
in place, check all your dimensions and spacing, check level
and plumb, fasten it, and you're done.
With a two-piece assembly, as soon as the lower run is
tacked and clamped in place, you can walk on it (carefully!)
while you're putting in the upper section. The joint where the
two sections meet has to be dead-on plumb and level, and
shimmed flush as needed (Figure 8). This location is a good
place to put fasteners, because the landing newel-post will
cover them up later.
Figure 8. The joint
at the landing newel (left) serves as a focal point for
aligning the entire stair assembly. The installer shims
and plumbs this location carefully, then screws through
the upper stair stringer into the lower stair riser to
firmly lock the joint (right). Fasteners at this point
will be covered later by the newel-post.
That center joint is the focus for the whole stairs -- you
get it right and pin it, and then adjust at the top and bottom
of the stairs if you have to. Most of the time in new
construction, everything fits right in place, but if there's
any planing or shimming needed in a remodel job, do it at the
bottom or the top.