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REAL ESTATE
AND
(Copyright, 1017, by The Record and Guide Co.)
NEW YORK, NOVEMBER 10, 1917
FINDING SUBSTITUTE METHODS OF BUILDING
Possibilities of Reinforced Concrete Cited—Use of Struc¬
tural Steel Could Be Minimized to Avoid Excessive Cost
By H. H. MURDOCK. of Jardine, HiU Ss Murdock, Architects
AT a time when building materials
are at a higher level than formerly,
and one's calculations, based on pre¬
vious standards of cost of construc¬
tion, are upset, it is interesting and
instructive to figure out what means
can be employed to offset these higher
prices of materials by substituting
other methods of construction.
An analysis of the cost of a large,
high-grade loft and show-room build¬
ing, built in the usual fireproof fashion,
with structural steel frame and brick
enclosing walls, with limestone for the
lower three stories and terra cotta for
the upper two stories, shows that if
this building were duplicated today
exactly as it was built in 1915-1916, the
increase in cost would be approxi¬
mately 40%, based on structural steel
costing $100 per ton erected. This
analysis also shows that if structural
steel could be procured at what it cost
in 1915-1916 that the increase in cost, if
the building were duplicated, would be
approximately 21%. In other words,
the rise in cost of structural steel
erected represents approximately one-
half of the total increase. _ Here, then,
we have a good opportunity to study
the possible substitutes.
Reinforced Concrete Possibilities.
Formerly cast iron was used almost
universally for columns and with good
results. There have been very^ few, if
any, cases of failures and even in a fire
cast iron has stood the test, if properly
fireproofed. The usual construction for¬
merly was cast iron columns and steel
or iron beams and independent walls.
Many of our older office buildings are
constructed in this way.
The use of reinforced concrete has
been growing more general. It has
practically supplanted mill construc¬
tion. It is used even in fireproof struc¬
tural steel frame buildings to a greater
or less extent. For floor construction
the usual construction is reinforced
concrete or terra cotta blocks or a
combination of reinforced concrete and
block. It has been used with satis¬
factory results, not only for the floor
slabs, but for beams and girders with
structural steel or cast-iron columns.
The interesting question is how much
further can the use of reinforced con¬
crete go toward reduction in cost of
building.
To ascertain what the difference in
cost would be at today's prices be¬
tween structural steel and reinforced
concrete for the frame work and rough
floor construction only, an analysis has
been made, using the known costs of
a ten-story, high-grade loft and office
building now being erected. This build¬
ing has approximately 11,000 sq. ft. per
floor, with regular column spacing, and
throughout 120 pounds per square foot
live load.
The counterpart of the steel frame
and rough floor construction, maintain¬
ing the same column spacing and
height of stories, has been estimated
in reinforced concrete. No attention
has been given to the walls, plastering,
finished floors, mechanical equipment,
etc.. it being desired to make the com¬
parison on the main frame work and
rough construction only. Every con¬
sideration has been given, however^ to
be sure that if the building were dupli¬
cated in reinforced concrete construc¬
tion the same architectural results
would be obtained. Manifestly, if
liberties were taken in order to make
use of adopted standards simply to cut
the cost the comparison would be of
no value.
This comparison shows a consider¬
able saving in favor of the reinforced
concrete frame work over sturctural
steel at today's prices, i. e., assuming
steel at $100 per ton erected. It shows
that at today's prices of cement and
bars that the reinforced concrete
frame can be built as cheaply as struc¬
tural steel frame, even if the price of
structural steel should drop to $70 per
ton erected, not to mention the fact
that if structural steel dropped to this
price reinforcing bars would also un¬
doubtedly drop too, giving the rein¬
forced concrete frame a still further
advantage.
The cost of reinforced concrete frame
and rough floors of this particular build-
in.e: would be $149,000, against a total of
$190,000 for structural steel and rough
concrete floors, with structural steel fig¬
ured at $100 per ton erected, a saving of
$41,000 at present market prices.
It must not be assumed that this
same saving would work out on every
building. To show the best compara¬
tive results floor area should be large,
column spacing regular and the height
not exceeding ten or twelve stories.
On two or three, or even five or six,
story buildings, the familiar wall bear¬
ing construction, with perhaps rein¬
forced concrete girders and beams and
cast iron or steel columns, will prob¬
ably figure out more economically than
all reinforced concrete. Apartment
houses that are likely to have
irregular column spacing and light floor
loads will not» as a rule, show a saving
in reinforced concrete.
Every one is familiar with the large
reinforced concrete buildings that have
been built in Brooklyn, Long Island
City and the Bronx, and a visit to other
cities impresses one with the larger
use that is made of reinforced concrete
for loft and show-room buildings and
often for office buildings and hotels.
For some reason there is an absence
of such buildings of reinforced con¬
crete on Manhattan Island. This may
be due to the fact that the large build¬
ings have been too high to build in
reinforced concrete. It may be that
the loaning institutions have hesitated
to make loans on reinforced concrete
buildings for fear they may collapse.
It may be that the Building Code was
not favorable to this type of construc¬
tion. (Since October 6, 1915, article
16 of the Building Code has been in
effect, setting forth the present re¬
quirements for reinforced concrete.)
And it may be that no one has thought
of the substitution or partial substitu¬
tions.
It is unquestionably true that there
has been a natural hesitancy to use
reinforced concrete because of failures
that have occurred just as there are
still people who are opposed to
sprinkler systems for fear of an un¬
expected—or perhaps they would say
expected—shower. These same people,
however, more than likely have their
offices in buildings with reinforced
concrete floor construction and stand
beside their safes with no thought of
a hurried trip to the basement. If the
prejudice against using reinforced con¬
crete horizontally has been overcome,
why should a similar prejudice remain
against using it vertically?
On any proposed building of the
general type suggested above, which
can be suitably constructed of rein¬
forced concrete, it would pay, at to¬
day's prices, to have it figured both
ways. To accomplish this it is essential
to have plans worked out for each type
of construction, and no one should
allow himself to oe persuaded that this
is not necessary.
The purpose of this article is not to
boom reinforced concrete, but only to
point out wherein savings by substitu¬
tion of materials may be made. Un¬
doubtedly this comparison could be
carried further ai.^, in other items in a
building, savings shown by using re¬
inforced concrete in place of brick, etc
Consideration must also necessarily be
given to column sizes and depth of
girders and beams as to whether the
reinforced concrete requires larger
sizes with the consequent heightening
of the building and reduction of floor
space.
^Monolithic Slab Construction.
On the floor construction itself it is
possible and in fact common practice to
use monolithic slab construction, that is,
casting the rough slab and applying the
finished wearing surface directly to it,
instead of introducing the usual cinder
fill on a cushion under the wearing sur¬
face. While this does not provide_ a
space to receive piping and conduits,
these can be cast into the slab. The
saving in this monolithic construction
is quite an item.
The possibilities of a combination of
materials offer plenty of opportunity
for savings, especially along the line of
use of cast iron for interior columns
and reinforced concrete exterior col¬
umns and walls. These uses can only be
suggested here, but were an architect to
approach a given problem with an open
mind unprejudiced against cast iron or
reinforced concrete unquestionably eco¬
nomical adaptations could be worked
out.
Consideration can also well be given
to the obtaining of materials as well
as their cost. Delays cost money. If
cement, gravel and bars can be ob¬
tained promptly and structural fabri¬
cated steel cannot, this is an important
item to take into account.
Progress is continually being made
toward improvement of building ma¬
terials and methods, and in the sub¬
stitution of materials and construction
to reduce the cost of building. At this
time with the changes that have taken
place in the prices of materials rela¬
tively, and on account of the price and
scarcity of labor, especially unskilled
labor, there is greater opportunity than
ever for constructive work along the
line of substituting other types of con¬
struction and materials, and especially
by the introduction in every branch, of
labor saving methods.
RBCORD AND GUIDE IS IN ITS FIFTIETH YEAR OF CONTINUOUS PUBLICATION.