The San Francisco call., 1897-06-20
TAXPAYERS VIEW
THE NEW ROOFING
Interested Citizens Visit
the City Hall for In
spection.
Mayor Phelan at Last Approve;
the Artiflc al Stone Over
Corrugated Iron.
Danger of Fire Thoroughly Averte
AM Plenty Of Light and V nti-
lstion Secured.


inspecting the new roof OF the City Hall.
So much has been said against and in
favor of the new plan of covering the mu-
nicipal building that property-owners.
who feel that after all they will have to
foot the bills, are taking advantage of the
chance to see the work while under way,
so that they may judge OF what the roof
may be when it is completed.
The contract is no small affair, as the
extent of surface to be covered must be
nearly three acres. Only small part is
completed, but all who have seen the re-
suit of the plans when fully carried out
have been entirely satisfied. At one time
it seemed that Mayor Phelan would stand
against Messrs. Creswell and Broderick,
the other members of the Board OF City
Hall Commissioners. but an inspection OF
a finished section of the roof convinced
him that wise choice of material had
been made.
During The progress of the erection of
the City Hall, extending over period of
some twenty-four years, it was found nee
essary to build the structure in sections,
provided for periodically by legislative
acts empowering the municipality 10 ap-
propriate sufficient sums for the work
acter OF roof-covering which would uIti-
mately be adopted each section of the
building, when completed, was protected
from the elements simply by temporary
roof Of the rudest character, formed of or.
binary wooden supports, with sheets of
corrugated iron on top.
Section by section was thus finished,
and while the entire structure stood com
plete in every other respect the root was
as above deser bed.
The present City Hall Comm issioners
having convInceu themselves that the
mansard roof, as originally contem plated,
was not the proper nor the practical COW
eIIng for the building, resolved finally to
place a roof which would be fire proof and
enduring and appropriate in every re-
spect.
Thy were confronted by the fact that
the City Hall, within which were situated
so many court cham bers County Clerks
offices and public and law ibrari s, with
their precious contents, was covered by a
thoroughly dangerous and infammable
roof, consisting of hundreds of thousands
of feet of lum Der and a light metal top
ping, which stood in imminent danger of
destruction by fire, and which would
necessltate, If fire occurred, the flooding
OF the building with water and the de-
struction of its contents.
After careful consideration of the many
varied characters of roofs suitable for i'm
mense structures they resolved finally 10
adopt a com binauon artificial stone and
metal covering, supported by an exte nsive
steel frame.
The past experience of the City Hall
Commissioners has been that the metal
roof and cutters have been destroyed by
people who, reaching the top OF the struc-
ture by stealth, have for their own profit
appropriated large quantities of lead ana
sheet copper, which acts were not at the
time discovered and which injury was
never known until the winter rains sud-
denly came pouring down through the
building.
A slate covering which received
thorough investigation was found not
practlcA ble owing to the slight incline of
the slopes, and because of the fact that
such covering would be subject to crack
ing by the walking of the workmen and
others over The surface. The same OBJ
iections were found applicable to the tile
roof.
The asphalt and gravel covering was
also given proper attention, and was much
discussed, but having been found only
suitable to very fat surface, because OF
the nature OF materials that kind of roof
was abandoned.
The object OF the commission was to
obtain for the building a roof which
would be i'm mperishable in case of fire, and
would provide excessive strength as
earthquake, and also one which would
necessltate the least repair, and, if in
Jured, would be most easily remedied, and
one which would afford the facility of
constant walking upon it by workmen or
Others such as is necessarily demanded
In every large building.
They therefore, after patient invest tiga-
tlon OF the value and CAPACITY of the
varied materials employed in buiIdinr,
found that OF all the most lasting and
most desirable was artificial stone. par
ticularly when re-enforced by metal They
found that the ext erience OF the past
also pronounced artificial stone as aImost
ind estructibe.
The experience of architects and engi-
neers shows that with age, unlike other
materials, artificial stone increases in
strength and durability and that The ar
pense of repairs to the City Hall roof
which IN the past has been enormous. will
be IN the future, thro gh this system of
roof, reduced to minimum. In fact. IL
VIII be almost nothing, as the roof is prac-
tically monolith with an iron basis
The metal being embedded in the arti-
fetal stone prod uces a roof so strong that
upon 1t may be placed extraordinary
weights, and any number of people walk
ing or romping upon it's surface will not
crack 1t or inIure it in any way.
a commendable feature of this roof is
that the ordinary metal cutters, which in
many buildings, to more or less extent.
stop up from the accu nulati of de bris
and dust in their contracted spaces and
overflow, or are torn and distorted by ex-
pansion and contraction, and injured BIZ
persons walking in or on them, have been
abandoned. Great inclined slopes at the
base OF the roof are formed of artificial
stone of the same character, and contin-
uation of the roof delivers the water with
greatest dispatch to the down pipes, or in
case of stoppage of the down pipes the
water passes out in overflow pipes above
he main cornice line.
A great deck platform rom feet to 10
feet in wild b is formed above the ridge of
the roof, perforated with large glass lenses
similar TO those found in the sidewalks of
the City, Illuminating thoroughly the en-
tire attic. and affoTding the means of ad-
hitting light through proposed light wells
from the attic to the various hallway
floors OF the building, which are now desti.
tute of natural light.
The great steel framework, which sup
ports the artificial stone root, consists of
trusses, purIines and columns weighing
$50 tons is of the best modern type, airy,
substantial and so braced as to form the
most rigid construction in conformity
with the great building beneath.
Ample space is provided beneath this
structure of steel for siorage-rooms of the
finest character. well ligh ted, and through
the system of louvre ventilators around
the deck line, extending over the sections