=23. Floor Construction.=—The floor construction of the building
consists of 3" × 6" yellow-pine pieces, set on edge and spiked
together. Such a construction as this is available for spans between
girders of from 10 to 15 feet, and does away with all secondary
girders, or beams. It also has an advantage in that it presents a neat
ceiling beneath when the edges of the planks forming the rough flooring
are beveled. On the top of this rough flooring, which is designed for
carrying the floor load, and which is so constructed that the joints
in the different pieces are broken, a 1-inch or 1¼-inch maple flooring
is laid. Maple is used for finished floors in factories principally
on account of its hardness and the excellent wearing surface that it
affords. The maple flooring available in the market runs in lengths of
from 3 to 16 feet, but the cost of the floor is greatly increased if
a minimum length of 6 or 8 feet is specified. Usually the flooring is
tongued and grooved and hollowed on the back, as indicated in Fig. 8.
The hollow back prevents the flooring from curling. In a better class
of finished flooring, the pieces are end-joined, or provided with a
tongue and groove on the end. This prevents the end of the flooring
from turning up and interfering with the smoothness of the floor and
the operation of trucks over it.
[Illustration: FIG. 9]
=24. Waterproofing and Dust Proofing.=—For the purpose of deadening
sound, and sometimes for the sake of waterproofing, sheathing paper or
felt is inserted between the finished flooring and the rough plank. By
the introduction of paper between the maple and the rough flooring,
dust and dirt are prevented from falling through the crevices due to
the shrinkage of the flooring boards above.
It is usual in finishing a floor around the edge to use about 2-inch
quarter-round molding, as indicated at _c_, Fig. 7. This molding is
also used around the wooden columns, or posts.
In order to prevent the posts from splintering at the corner, and
so that there is less likelihood of the occupants being hurt, a
stop-chamfer, or arris, is formed on the corner.
=25. Splice Pieces.=—There is one feature which must not be overlooked
in mill construction, such as occurs in this figure, and that is that
since the girders butt against the columns on top of the post caps,
usually flush, there is nothing to carry the boards at _d_, therefore
yellow-pine pieces or steel angles must be provided, as indicated at
_e_. These splice pieces answer two purposes, namely, to form a bearing
for the ends of the planks _f, f, f_, and also to tie the girders
rigidly together longitudinally, and thus increase the rigidity of the
floor construction.
For a similar reason, it is necessary to form a ledge, either by
reducing the size of the pier above, or by corbeling out, at the window
openings, as shown at _g_, for the support of the floor planks at _h
h_. On the top of the corbel so formed, usually a 3" × 8" yellow-pine
piece is securely anchored to the wall, to provide a bearing for the
ends of the rough floor planking.
=26.= Reference to _i_ and _j_, Fig. 7, shows that there is very
little room between the head of the window and the bottom of the
floor construction. By this means, the maximum amount of light near
the ceiling is obtained, and, besides, the ventilation is greatly
facilitated. This is one of the important features in factory
designing, as well as in school-house architecture.
=27. Foundation Walls and Piers.=—From the section of the wall shown
at _k k_, Fig. 7, it will be observed that the entire building is
practically supported on heavy piers, and that the 13-inch walls below
the window sills are only spandrel fillings. In some instances, 9-inch
walls can be used in these places, but it is not considered advisable
from the fact that beating rain will readily drive through a 9-inch
wall, and, besides, there is hardly sufficient sill for a heavy window
frame.
Attention is particularly called to the construction of the window sill
at _l_. In the better class of construction, heavy bluestone sills 5½
in. × 7½ in. would be used; but for cheap work, it is customary to use
a light 3" × 5" bluestone sill.
Where spandrel fillings more than 13 inches in thickness are used, or
where the thickness of the wall is much greater than the frame, as
indicated at _m_ in the basement, beveled bricks on edge are used for
forming the sloping wall inside. The purpose of the sloping sill is to
prevent the corners from being broken and damaged, and employes from
occupying them.
=28. Terra-Cotta Window Heads.=—In factory construction, the use of
terra-cotta window heads is not unusual, and the construction of such
a window head is indicated at _n_, Fig. 7. Where terra-cotta window
heads are used in this manner, some means of support must be had for
the brickwork above the window head, as terra cotta in itself is of
little use as an arch, or lintel. It is not uncommon to use angle irons
back to back, as indicated on the section of window head _n_. This
construction, of course, can only be used where the wall runs parallel
with the supporting floor, for if the head of the window receives beams
or girders it must necessarily be more strongly and rigidly constructed
with heavy channel irons, or =I= beams.
Where the windows of the basement, as shown at m, are brought down
close to the pavement, it is absolutely necessary that the pavement be
sloped away from these windows with considerable pitch, not less-than
1 inch in 1 foot, as otherwise the water is likely to lay against the
window sill or run under it, causing it to rapidly decay, the capillary
attraction of the window frame drawing up the water.
[Illustration: FIG. 10]
=29. Window Openings.=—Referring to Fig. 9, which shows the face view
of a bay of the wall illustrated in section in Fig. 7, the details of
the several window openings in the walls may be studied. The basement
windows are independent frames with double-hung sash, a rowlock brick
arch supporting the brickwork over the window head. In the practice
and design of window heads for mill buildings, it is usual to make the
radius of the window head equal to the width of the reveal. In this
instance, the distance across the opening is 4 feet 3 inches, and the
radius of the arched head is the same dimension.
The windows throughout the balance of the building are twin windows,
double hung, and the construction of the window frame and sash is shown
in the drawing. This frame is what is known as a =reveal frame=, and
is built in as the brickwork progresses. Sometimes the frame is slipped
in from the back, as shown in Fig. 10, and when this is the case the
work can be carried along without waiting for the window frames.
[Illustration: FIG. 11]
As distinguishable from the reveal frame, there is the =plank-frame
construction=, which is not built into the brickwork, but is built up
as shown in Fig. 11. When it is desirable to have the central mullion
_a_, Fig. 9, as narrow as possible, the box construction indicated
on the drawing is done away with and the window is hung by means of
overhead pulleys, the weights operating in the boxes at the sides.