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A treatise on architecture and building construction, prepared for students of the International Correspondence Schools (Volume 3) online

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THE LIBRARY

OF

THE UNIVERSITY
OF CALIFORNIA

LOS ANGELES

GIFT OF

ALLEN P. ST1TH



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A TREATISE

ON




PREPARED FOR STUDENTS OF

THE INTERNATIONAL CORRESPONDENCE SCHOOLS

SCRANTON, PA.



STAIR BUILDING, ORNAMENTAL IRONWORK

ROOFING, SHEET-METAL WORK

ELECTRIC-LIGHT WIRING

AND BELLWORK

WITH PRACTICAL QUESTIONS AND EXAMPLES



First Edition



SCRANTON

THE COLLIERY ENGINEER CO.
1899



Entered according to the Act of Congress, in the year 1890, by THE COLLIERY

KNGINEKR COMPANY, in the office of the Librarian of

Congress, at Washington.



PRESS OF EATON & MAINS,

NEW YORK.








CONTENTS.



STAIR BUILDING. Section. Page.

Introduction 11 1

Stairway Construction 11 2

Details of Construction 11 6

Balustrades 11 18

Stairway Design 11 22

Ordinary Forms of Stairways .... 11 22

Special Forms of Stairways 11 47

Wainscoting 11 54

ORNAMENTAL IRONWORK.

Introduction . 12 1

Cast-Iron Work ......... 12 2

Cast-Iron Stairs 12 17

Wrought- Iron Work 12 38

Office Grilles 12 49

Elevator Enclosures 12 54

Elevator Cars 12 74

Leaves and Foliated Work 12 85

Forged Work 12 91

Gates and Fences 12 93

Window Guards 12 100

Lamps and Brackets 12 105

Iron Structures 12 112

ROOFING.

Historical Introduction ...... 13 1

General Terms and Definitions .... 13 7

Varieties of Roofs 13 7

iii



iv CONTENTS.

ROOFING Continued. Section. Page.

Parts of a Roof 13 10

Design and Construction of Roofs ... 13 11

Thatching 13 14

Asphalt Roofing 13 17

Asbestos Roofing 13 21

Shingle Roofing 13 24

Tin Roofing 13 35

Sheet-Metal Shingles 13 49

Copper Roofing 13 55

Galvanized Sheet-Iron Roofing .... 13 6-1

Black Sheet- Iron Roofing 13 67

Sheet-Lead Roofing 13 71

Sheet-Zinc Roofing 13 77

Slate Roofing 13 81

Tiles 13 94

Glass Roofs 13 103

Stone Roofs 13 110

Flagpoles 13 113

Snow Guards ; 13 114

SHEET-METAL WORK.

Uses of Sheet Metal 14 1

Exterior Sheet-Metal Work 14 2

Wall Coverings 14 3

Cornices 14 7

Window Sills, Lintels, and Caps ... 14 17

Columns 14 20

Fire Doors and Shutters 14 21

Copings 14 23

Balustrades 14 26

Gutters 14 30

Conductors 14 41

Domes and Lanterns 14 47

Crestings 14 55

Finials 14 56

Interior Sheet-Metal Work 14 59

Materials Used in Sheet-Metal Work . 14 60



CONTENTS. v

ELECTRIC-LIGHT WIRING AND BELLWORK. Section. Page.

Electric- Light Wiring ..15 1

Fundamental Principles of Electricity .15 1

Wiring for Incandescent Lights ... 15 10

Wiring Calculations 15 41

Bell Construction and Operation ... 15 55

Annunciators 15 65

Special Electric Fittings 15 69

Electric Door Opener 15 69

Burglar Alarms 15 71

Electric Gas Lighting 15 72

QUESTIONS AND EXAMPLES. Section.

Stair Building 11

Ornamental Ironwork 12

Roofing 13

Sheet-Metal Work 14

Electric-Light Wiring and Bellwork 15



STAIR BUILDING.



INTRODUCTION.

1. Stair building grew out of the necessity of securing
an easy and safe passage from one level, or floor, to another.
Such a passage might therefore be regarded in its inception
as an inclined plane which connects two horizontal planes
and provided with a series of equal risers, or steps, formed
for the purpose of giving a sufficient footing to facilitate
travel.

The construction of wooden stairways is considered the
highest branch of joinery; more care and knowledge are re-
quired in their planning, more ingenuity in setting them
out, and more skilful workmanship in their execution, than
in any other work about a building.

The architect, in studying the plan and treatment of a
stairway, should consider its adaptability for the building in
which it is to be placed, its proposed situation, the weight
likely to come upon it, the width to accommodate probable
travel, and, especially, the ease of travel. It is not enough,
as is sometimes done, to roughly calculate the treads and
risers and sketch on the winders, leaving the stair builder to
make the best he can of the conditions.

The first and most important consideration in designing
stairways is their disposition for obtaining the utmost facility
of access to the various stories to which they communicate.
Care should be taken to secure proper headroom while
ascending and descending, and the treads and risers should
be arranged so as to secure easy travel. The proper width



2 STAIR BUILDING. 11

of the stairway has also much to do with its appearance ; in
a private house, it should never be less than 2 feet 8 inches
wide, and in public buildings never less than 4 feet 6 inches.
The staircase wherein the stairway is enclosed should be
given special attention, and the correct length and width
should be carefully considered. It is not conducive to sound
construction to be obliged to cut out trimmer beams; neither
is it good practice to have to piece out a few inches when
the staircase has been framed too large.

The importance of proper arrangement of stairways is
evident, when it is considered that they are seen by every
one, their convenience and beauty being readily appreciated,
and their faults and defects instantly detected.



STAIRWAY CONSTRUCTION.



MATERIALS USED.

2. The materials most commonly used in the construc-
tion of stairways are stone, iron, and wood ; the selection of
material should be based on the location and the use to be
made of the stairway. If placed outside of a building, stone,
owing to its natural capability of resisting atmospheric influ-
ences, should be used; while, if placed inside a building
designed to be fireproof, iron is generally selected, as it
possesses great resistance to heat. Both iron and stone are
preferable to wood when used in public buildings, where
the amount of travel requires extra strength; wood, how-
ever, is the material most commonly used, especially in pri-
vate buildings, where no heavy travel is to be expected.



TERMS USED IN STAIR BUILDING.

3. In stair building, a riser and tread together are
termed a step, the riser being the upright portion which
supports the tread, or horizontal part, upon which the foot is
placed. The nosing is the projection of the tread beyond
the face of the riser.



11 STAIR BUILDING. 3

The term run is applied to the aggregate width of the
treads.

Where the risers are parallel to each other on plan, thus
forming straight steps, the steps are called fliers ; but where
the risers radiate on plan, forming triangular treads, the
steps are called winders.

The term flight designates a succession of steps between
one starting place and the one next above it. The spaces
wider than steps, which constitute resting places between
the nights, or which are the terminations of the stairways,
are termed landings, or platforms. If the landing is square
and occupies half the width of the stairway, it is called a
quarter-space landing; but when it takes in the full width
of the stairway, it is called a half-space landing. The
space required for landings is sometimes filled in by winders ;
this is especially the case in geometrical stairways and those
in which the run is limited. In every case, it is the quan-
tity of space in the run that decides the nature of the land-
ing, whether it is to be quarter or half space, or filled in with
winders. Where the run is unlimited, a half-space landing
should be adopted; but where the run does not allow this
kind of landing, a quarter space is preferable to winders, as
the latter should never be put in a stairway when they can
be avoided.

The lower step of a flight sometimes has its outer end in
the form of a horizontal spiral, and is then termed a curtail
step. When the lower step is rounded to a semicircle, it is
known as a bull-nose step. Where steps have an outward
curve, they are called szvelled steps; this form is generally
tised when the front stringer is curved out at the starting of
the stairway.

If, in ascending a stairway, the hand rail is on the right-
hand side, the stairway is called a right-hand stairway. If
the hand rail is on the left-hand side, the stairway is called
a left-hand stairway.

The above are some of the more common terms used in
stair building ; others will be explained as occasion arises
for their use.



4 STAIR BUILDING. 11

GENERAL CLASSIFICATION.

4. Stairways are known as dog leg, open newel, and
geometrical. A C!OK-IOK stairway has no well hole, and the
face stringer of the upper flight is vertically over that of
the lower one. A well hole is the space on plan between
two flights when the stringers are not located in the same
vertical plane. The objection to dog-leg stairways is that
the hand rail is not continuous, but strikes the soffit of the
upper flight.

Where newels are placed at the angles of the well hole,
the stairway is termed an opeii-iiewel stairway; but when
the stringer is continued in a curve perpendicular to the
curve on the plan round the winders, the stringer is said to be
wniitlHMl, and the stairway is designated as geometrical.

5. The above classification relates more especially to the
general design than to the structural details, many of which




arc common to each. When classified with relation to the

s of construction, there are two systems-, the first

n the use of rough timbers, or carriages, cut to the



11



STAIR BUILDING.



angle of intersection between the treads and risers, as shown
in Fig. 1 ; the other, which is the more generally used, has
the treads and risers grooved, or housed, from f to ^ inch,
into the prepared stringers. In the first case, the .treads
and risers are nailed on the carriages, and, where they inter-
sect with the wall, a board of the same thickness as the
baseboard connecting with the stairway is scribed, or cut,
to the required outline so as to fit closely the angles of treads
and risers; this runs the full length of the stairway, forming
what is termed the \vall stringer. In favor of this method
of construction are its simplicity and strength. Against its
adoption may be adduced the great difficulty of satisfactorily
scribing the wall stringers, and even when this is success-
fully done, the stairway is likely, in time, through shrinkage
and jarring, to show imperfections.

The carriages, also called horses and springing trees,
for the second form of construction of stairways, are not cut




FIG. 2.



to the angle of treads and risers, as is the case in the first
method, but are simply straight scantlings of sufficient



G STAIR BUILDING. 11

strength to support the stairway and its probable load, rough
brackets being nailed on the sides of these scantlings and
fitted tightly under each tread, as shown at a, Fig. 2. In
some cases, where the treads and risers are enclosed in
stringers, the wall stringer only is housed to receive the
treads and risers, the front, or outer, stringer being cut
square to receive the tread, and mitered to receive the riser.
When thus prepared the front stringer is termed a cut-aiul-
uilierrii, or oiM'ii, stringer, the wall stringer being termed
a housed stringer. Occasionally both wall and front string-
ers are housed, in which case the front stringer is said to be
a close stringer. Geometrical stairways are seldom thus
constructed, the method being mostly confined to dog-leg
and open-newel stairways.

In geometrical stairways, the front stringer is cut and
mitered so as to meet the conditions arising from the
wreathed portion of the stringer and rail, which are assumed
to stand perpendicular to each other and in the same verti-
cal plane. The rail in this case is wholly supported by the
balusters, instead of by the newel, and the cut-and-mitered
stringer affords a substantial footing to the balusters, which
are dovetailed, glued, and nailed to the ends of treads; the
nosing and molding of the treads being returned their full
width on the face of the stringer. vStairs thus constructed
are said to have nosed and mitered moldings, and when
brackets are placed along the front stringer below the
nosing, the stairway is known as a bracketed stairway.



DETAILS OF CONSTRUCTION.



RISERS AND TREADS.



6. Height of Risers. In setting out a stairway, the

t consideration should be to ascertain the exact height

:\vecn the floors, the height to be measured from the top

of the floor below to the top of the floor above. For this



11 STAIR BUILDING. 7

purpose, a rule or rod is sometimes used, termed a story
rod, on which the whole number of risers is to be marked.
Care should be used in determining the risers, with the view
of constructing a stairway having steps of convenient height.
Experience teaches that between 6 inches and 7 inches rise
is the limit of easy stepping; therefore, the total height of
the story rod should be divided by either one of these num-
bers, which will give the number of risers required. Hav-
ing in this manner ascertained the number needed, divide it
into the height of the story rod; the quotient will be the
exact height of each riser.

7. Proportioning Treads and Risers. The next step
is to ascertain the width of the treads, not forgetting the
rules of proportion between treads and risers, and always
remembering that the number of treads in each flight is one
less than the number of risers; this is owing to the landing
being counted as one tread.

There are several rules for determining the proportion
which should exist between tread and riser for regular
stairways, and upon which depends not only the appearance
of the stairway, but the ease with which it may be traveled.

Three rules will be given, of which the first is the simplest,
and is generally preferred.

Rule I. Let the product of the tread and riser equal the
number 66.

For example, assume that the riser is six inches high, then
the width of the tread will be 66 -=-6 11 inches. In the
same way, the width of tread may be assumed, and the height
of the riser found.

Rule II. To any given height of riser in inches, add a
number that will make the sum equal 12; double the number
added, and the result will be the width of the tread In inches.

For example, assume that the height of a riser is 7 inches;
then 7 + 5 = 12, and 5x2 = 10, the width of the tread in
inches.



STAIR BUILDING. 11

Rule 111. Draw a right triangle, as slunvn in Fig. 3, with
a base of 24 inches and altitude of 11
inches. Mark the width of tread from
a on line a b,as a c; at c erect a per-
pendicular, cutting the hypotenuse at e.
Then c c indicates the riser.




Fit;, a



IIEA1>UOOM.

8. In trimming joists of staircases, the two cross trim-
mers which are called headers should be so placed as to
allow sufficient headroom to meet all probable requirements
of a stairway. The header (which determines the headroom)
should be placed so as to secure 7 feet of headroom from the
tread vertically beneath it. A careful drawing of the eleva-
tion of the stairway will accurately determine this point.

In cases where a number of winders are placed at the
bottom of a stairway, and the risers thereby stand one above
the other at the center from which they radiate, a consider-
able rise is produced at the commencement of the run, the
amount depending on the number of winders. In such a
case, the header is placed at the extreme end of the stair-
case, and thereby ceases to be a factor in the headroom.
This applies especially to boxed stairways, which are enclosed
between partitions.

Care should also be taken to make the staircase of the
correct width, which should be at least 5 inches wider than
the width of the stairway; that is, the distance from the
center of the rail of the flight to the facia of the floor land-
ing should be at least 5 inches, to permit the rail to pass
clear of the nosing on the landing.



STRINGERS.

9. Laying Out. A straight stringer is laid out by
means of a pitch board, shown at (a) in Fig. 4. This board
should be made of thin wood, with the grain parallel to the
hypotenuse, so that the effects of shrinkage will be the least



11



STAIR BUILDING.



possible. The base is cut to equal the tread, and the perpen-
dicular to equal the riser. At (b) is shown the stringer, as
marked out for the steps ; the dotted line a b is drawn at a
sufficient distance from the edge, so that the lower edges of
the riser and tread will intersect on the line of the under
side of the stringers, as shown at d. On the line a b, step
off, with dividers, distance equal to the slope length of the
pitch board. The latter may then be applied as shown, and
its outline marked on the stringer edges. Templets, as





PITCH BOARD.

(a)




FIG. 4.

shown at (r), should be made for the treads and risers, care
being taken that the pitch in both cases is alike, so that the
same shaped wedges can be used. The lines a deb show
the section of the tread, and a ef shows the shape of the
wedge. The tread and riser templets, when applied to the
stringer, should have their outer edges coincide with the
lines made from the pitch board, giving the outline shown
at S.

To form the housing, holes are bored in the stringers
adjacent to the nosing of the tread, as at c, and that portion
is removed by means of a chisel. The lines of the templets
may then be cut to the depth of the groove by a saw, and
the material removed with a router plane.

Such a stringer is shown in Fig. 5, with the exception
3-2



STAIR BUILDING.



11




Fir,.



treads and risers are attached to the stringers, wedged, and
glued into the housing, and the whole taken bodily to its
place in the building. The wedges are shown in place at b
and ,, Fig. 5.




Fir.. 6.



The wall stringer, as shown in Fig. G, and also the front
stringer, if a close one, are each grooved as already explained,



11



STAIR BUILDING.



11



the depth depending- upon the thickness of the stringer.
Two or more carriage timbers are used in the width of the
stairway, the number, depth, and thickness depending on
the width of the stairway and the load to be carried.

The front stringer, as shown in Fig. 7, is well nailed to the
front carriage timber a, while the other timbers are rough




FIG. i.



bracketed under each step alternately on the sides, and
nailed as shown at a, Fig. 2. A furring strip is nailed to
the wall in line with the lower edge of the carriage timbers,
to receive the lath.

The prepared mortised wall stringer is nailed to the wall
to square properly with the previously set carriage timber
and front stringer.

1O. Scribing Wall Stringers. When the treads and
risers are supported by rough cut carriages, it becomes
necessary to cut a wall stringer that will fit around the
steps and make a finish with the wall. In Fig. 8 is shown a
method of scribing a wall stringer. The stringer is repre-
sented as being laid with one edge on the line of the nosings,



13 STAIR BUILDING. H

and the instrument to be used is shown in position. The
hard-wood or iron bar bh has a hook on the lower end pro-
jecting sufficiently to enable the bar to clear the nosing when
the point b is touching the face of the riser. The bar b k is
placed against the guide ;// and loosely bound to it by the




FIG. 8.

metal straps e and /'. The strip n is fastened to m by a
bolt a, which can be tightened so as to preserve the bevel.
A small nick is made in the sliding bar b h at c, so that b c is
the height of a riser. When the point b is on the end of the
nosing, the nick c gives the position of the corresponding
point on the wall stringer. Other points may be found in a
similar manner, and the outline to which the wall stringer is
to be cut can then be drawn.



CONSTRUCTION OF STEPS.

11. A portion of the upper edge of the riser maybe
tongued into a groove in the under side of the tread, as shown
at a in (a), Fig. 9, instead of letting the whole thickness of
the riser into the tread, as shown at (b). The lower edge of
the riser may also be tongued into a groove in the upper



11



STAIR BUILDING.



13



surface of the tread beneath it, as shown at b in (a), in

which case the tread

would have to be

nailed up into the riser

as at c\ this method,

however, does not give

as good results as that

shown at a in (b).

The finished treads
and risers are glued,
and clamped together
with handscrews until
the glue has set. From
two to four well fitted
blocks are then glued
and nailed to the in-
ternal angle of the
tread and riser, as
shown at b in (b). In
Fig. 9 (b) are also shown
the dovetails for insert-
ing the balusters.

12. Bull-Nose

Steps. A form of step

much used is represented in
Fig. 10. The solid block is
sawed into shape, and the riser
is sawed out as shown, leaving
a veneer for the face of the riser.
The end b is firmly fastened to
the solid block with screws. At
a square hole is left the full
depth of the riser, into which
wedges are driven from each
end, as suggested at d. The
back of the veneer is covered
with glue, and, as the wedges
FIG. 10. are driven home, it is clamped





u STAIR BUILDING. U

firmly against the face of the block. The newel is generally
set on top of this step, as indicated by the dotted lines. The
second riser may be placed in the middle of the newel, as
indicated at c, or in any other position desired.

13. Curved Risers. Where risers are curved, they
should be made of solid wood, or of curved strips of seasoned
wood glued solidly together. It is often difficult to get sea-
soned wood in pieces large enough to make a solid curved riser.
In such cases it is desirable to bend pieces of 1-inch board
by kerfing. Fig. 11 illustrates the method of finding the



^






\\



\ \
\ \
\ \



FlO 11.

distance between kerfs for a curve of given radius. The
method is as follows: Cut one kerf, as at a; then, marking
the distance a d equal to the radius a o, bend the board to
position a b until the saw kerf is closed, as shown. Measure
the distance between d and , or, in other words, the deflec-
tion of the board between a and b. This length db is,
therefore, the distance between kerfs, which, if continued,
will shape the board to the curve a e. All the kerfs must be
made with the same saw.

14. Platforms. Where the stairways of a building are
of considerable length, and are straight in plan, it is best to
break the flight by a platform. Such a platform may be
projected from the side wall, as shown in Fig. 12. In a



11



STAIR BUILDING.



15



brick wall, the lookouts a, a should be set in at least 8 inches
with slip keys tightly wedged between the bricks and the
top of the timbers. The braces , b should be well fitted




FIG. 12.



and spiked to the lookouts; these braces serve to keep the
platform square and enable it to resist distortion by stress
brought to bear on the carriage timbers c, and should be




FIG. 13.



made of thoroughly seasoned wood. A flight terminating
in a platform should not contain more than 12 steps. A
perspective sketch of the platform is shown in Fig. 13.



CYLINDERS.

15. In geometrical stairways, the hand rail travels,
unobstructed by newels, from the first step to the last, some-
times over six or more nights ; it then becomes necessary to
wreath the stringer and rail around the well holes. The



16



STAIR BUILDING.



11



well holes thus treated are said to contain a cylinder. In
stair building, any form of a curve constitutes a cylinder
when used for this purpose. In a circular stairway, the
cylinder assumed has a complete circumference of a circle
for its plan, and the stringer and rail are made to wind
around it, following a curve termed a helix a curve of the
same nature as the winding thread of an ordinary screw.
The finished treatment of the stringer and balustrade is con-
tinued around -the cylinder, and where the stairway termi-
nates in a landing, the same treatment is continued along
the trimmer beam. The portion on the beam corresponding
to the stringer is called the facia. Thus it will be seen that
the stringer of the flights, the cylinder of the well hole, and
the facia of the trimmer beam are but parts of one continued
stringer known by different terms.



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