Improvements in the Construction of Fire Resisting Floors.
Year: 1893

page_text: Date of Application, 30th Nov., 1893
Complete Specification Left, 1st May, 1894-Accepted, 18th June, 1894
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Fire Resisting Floors.
I, THOMAS POTTER, of Grange Park, Alresford, Hants, Clerk of Works do
hereby declare the nature of this invention to be as follows:-
My invention consists of the combination of various materials, and in different
ways, for the better protection of the steel and iron joists, &c. used in constructing
fire resisting floors and ceilings, and in the general construction of fire resisting
floors and ceilings, and which consist mainly of improvements with regard to certain
methods of performing the same objects for which a Patent was granted me on the
Nineteenth day of February A.D. 1893, No. 4259.
In constructing a hanging ceiling attached to steel or iron joists, I use metal bars
or rods, resting upon the bottom flanges of the joists, and reaching from joist
to joist.
I crank the bars or rods at each end to enable them to hang down below the
joists, and to which metallic lathing and plastering is fixed.
The object of cranking the bars or rods is to enable a ceiling to be formed clear
of, and free from contact with the joists. I crank the bars at right or acute angles,
as may be necessary; and if required I make mortices, or attachments in the cranked
ends, and fix short bars thereto, passing under the bottom flanges of joists, to enable
tiles, concrete, asbestos, or other non-combustible material to be laid thereon as a
further protection against the effects of fire.
Another way of effecting the same object is to employ metal hangers, (similar to
those shown by Fig. 5 in drawing accompanying my Specification dated Feb. 27,
A.D. 1893, No. 4259) and shouldering, or cranking these in the way just described,
and making mortices therein for holding loose bars of metal, or attaching the latter
in any other convenient way for the purpose of affixing metallic lathing thereto.
These hangers may be made to clip or rest upon both sides of the iron joists, and
in one piece of metal, or they may be made in two pieces and fastened together by
means of bolts and nuts, or otherwise, below the bottom.flange..
Additional protection may be given to the bottom flanges of the joists by affixing
in mortices, or otherwise, two loose metal bars, instead of oue, and a short distance
apart, to enable a double covering of metallic lathing and plastering to be used.
I form the floor by using concrete burnt clay, or other blocks, upon which
permanent centering of corrugated iron is laid of any desired curve or shape, as
more fully described in the Patent previously referred to dated Feb. 27 A.D. 1893
No. 4259. Where very great protection from fire is necessary I also use fireclay,
common clay, or concrete blocks, and grooved so that the upper portions rest upon
the bottom flanges of the joists, and the under portions are beneath the joists.
These blocks being fixed on each side of the joists, meet in the centre of the
bottom flange, where they butt against each other, or are grooved, V jointed or
otherwise arranged to key together. These blocks are not of the nature of skew
backs, but form bearing blocks for supporting corrugated iron centres for concrete
floors, or clay or concrete blocks are bedded on them for a similar object.
Where very great width of flange has to be covered, I foreshorten a portion of
the blocks which passes under the flanges, so as to form a groove or channel to
enable tiles, slabs of any kind, asbestos, or some similar material to rest upon the
projections of the blocks and in this way protect the bottom flanges of the beams
or joists from great heat.

page_text: To more completely protect the portions of iron or steel box girders which,
owing to their great depth, often project below the general ceiling line, I use metal
bars attached to the bottom flanges, and turned down at right angles at each end.
In each of the turned down ends I make mortices through which iron bars pass,
and project beyond the said ends. To these ends I bolt or otherwise secure, vertical
bars of iron, which I secure to the top flanges of the beams in various ways.
Metallic lathing is fixed to the vertical bars and to the horizontal bar passing
through the turned down ends, and the lathing is plastered in the usual way,
securing a complete encasement of the beam or girder.
I also case the sides of box girders or beams, as a fire protection, with concrete
or brick blocks resting upon the bottom flanges, and these 1 employ also to support
the common iron or steel joists which are fixed at right angles to the girders.
Dated this 29th day of November 1893.
THOMAS POTTER.
Improvements in the Construction of Fire Resisting Floors.
I, THOMAS POTTER of Grange Park, Alresford, Hants Clerk of Works do
hereby declare the nature of this invention and in what manner the same is
to be performed, to be particularly described and ascertained in and by the following
statement:-
My invention relates to the construction of fire proof floors, and ceilings, and is
an improvement on Patents granted me on February 7th 1891 No. 291 dated
7th January 1891 and on 19th August 1893, No. 4259 dated 27th February 1893.
My objects are 1st to totally disconnect floors from the ceilings beneath; 2nd to
form a series of hollow chambers in which gas pipes, electric light wires &c. can
be safely deposited, and to facilitate means for artificial ventilation; 3rd to prevent
the transmission of sound from apartments beneath the floor, to apartments above,
or over the floor; and 4th to reduce the weight of materials usually employed in
the construction of fire-proof, or fire-resisting floors.
In carrying out my objects, I crank metal bars, rods, or tubes, at one end, to
clip the bottom flatiges of steel or iron joists. The other end of the metal bars,
rods, or tubes which hereafter I call "hangers "-I also crank to form a bearing
for bars or tubes of metal called "lathing bars" to rest upon. The hangers are of
a length, that, when suspended from the metal joists, and the lathing bars rest upon
their bottom portion, a cavity is left between the latter and the bottom flanges of
the joists, forming an air space to check the transmission of heat in case of fire.
I sometimes make two hangers and a lathing bar of one piece of metal, so as to
span from joist to joist, but preferably I make the hangers separately with a mortice
in each for the lathing bars to pass through, so that the bearing bars may be of an
independent nature i.e. merely resting on the hangers, and in this way allow freedom
for expansion in case of a conflagration. The purpose of the lathing bars is to
take the place of the ordinary wood ceiling joists, and uphold metallic netting or
lathing, which is wired to the lathing bars; plastering mortar of any description is
then applied to the metallic lathing or netting, and a fire resisting ceiling giving
great protection to the floor above is in this way constructed. To form the floor
proper cover and encase the bottom flanges of the joists with blocks made of
burnt fire clay, common clay, or concrete, and I leave an air space between the
blocks and the bottom flanges of the joists. The blocks being laid dry, or bedded
with mortar on each side of the joists, and on the flanges, meet in the centre of the
'under side of the latter, where they either butt against each other, or if preferred
are rebated, grooved or keyed together. These blocks which I call "flange casings,"
are not of the nature of skewbacks, or abutments of an arch, but constitute bearing
blocks for corrugated iron centres to support concrete in a soft state, to form floors.

page_text: As, however, the requirements for fire proof floors vary a great deal with regard
to the necessary amount of resistance to a fire, the weight to be supported, and
otherwise, 1 vary the details of my invention in different ways. For instance
Figure 1 is a section of a floor and ceiling where it is desirable to minimise the
quantity of concrete to be used for the floor proper, and to effect this I employ
blocks of concrete or burnt clay resting upon the flange casings. A is a concrete
floor-C flange casing-D hanger-E lathing bar-F metallic lathing-G plastered
ceiling-H corrugated iron centre-J air cavity-L steel or iron joist-M bearing
block.
The method of construction is as follows,-When the joists are fixed, the
flange casings C are placed in position, the hangers D, which may be from an inch
to one and a half inch in width, are suspended to the flange casings, and about
12 inches apart, the bearing blocks M are bedded with mortar or cement on the
flange casings C, the corrugated iron centres H are laid on the blocks, and
concrete A in a soft state is deposited thereon to form a floor, which may be
hereafter covered with cement. tiles, or wood in the usual way.
The lathing
bars E are next fixed by passing them through mortices made for the purpose
in the iron hangers D, and wire netting or metallic lathing is wired to these
bars; lastly a plastered ceiling G is executed in the ordinary way.
Figure 2 is a section of a floor similar to Figure 1 except that I foreshorten
the under portion of the flange casing C and slide in burnt clay, or concrete
rebated blocks B; this form of construction would be desirable where the bottom
flanges of the joists were unusually wide. The reference letters are the same and
apply in the same way as for Figure 1.
Figure 3 is a section of a similar floor and ceiling, but to provide for cases where
the form of flange casing is not adapted, I use an extra short length of lathing
bar K from a to b placed alongside the usual lathing bars E, to create increased
strength or stiffness for the purpose of supporting the form of flange casing shown
by C which is made of burnt clay or concrete. The mortices in the hangers D
are made sufficiently wide to admit the passage through of the two lathing bars E
and K. A is a concrete floor-B any kind of tile, wood, or cement casing-
C flange casing-D hanger-E lathing bar-F metallic lathing-G common
ceiling--K short length of lathing bar a to b-L steel or iron joists.
Figure 4 is a section showing another variation of the same floor adapted for
purposes where the concrete is required to be deeper than usual to obtain great
strength. In this arrangement the flange casings C are rebated, grooved, recessed,
or made with a projecting lug to give an abutment to the corrugated iron centres H
which are supported by the flange casings. A is a concrete floor-C flange casing-
D metal hanger-E lathing bar-F metallic lathing-G common plaster ceiling-
H corrugated iron centre-J air space.
Figure 5 is a section showing an arrangement for executing floors without the
ceiling portion, and using corrugated iron centres temporarily, and not to form
permanent centering. Temporary. iron hangers B are passed over the joists at
intervals to uphold a wood plank P in the manner shown, N is a bearing block of
wood, fixed at intervals or in one continuous length, having an iron bar fixed to the
top portion to receive the thrust of the corrugated iron H which rests upon the
bearing block N. After the concrete has been deposited in place, and is set
sufficiently, the nuts on the hangers B are unscrewed, which liberates the block N,
the plank P, and the corrugated iron H, that they may be re-used for a similar
purpose elsewhere. A is a concrete floor-B hanger-C flange casing-
H corrugated iron, N bearing block and P the supporting wood plank.
Figures 6 and 7 are cross and transverse sections respectively, of a compound
girder projecting below the general ceiling line, in connection with fire proof floors
and banging ceilings, executed in either one of the ways previously described.
A is a compound girder; D hangers of iron or steel of any convenient size, a foot
apart, suspended to and clipping the flange casings C; E a lathing bar fixed in the
same way as described at the commencement of this Specification; F metallic

page_text: Jathing of any suitable description, which is wired to the lathing bars E and to the
hangers D; ordinary plastering mortar G is applied to and upheld by the metallic
lathing F; B is a floor joist of usual dimensions fixed to the compound girder on
angle plates, in the usual way; H is asbestos or other non conducting blocks, or
pads, fixed at intervals on the angles of the bottom plates of the compound girder A,
to retard the passage of heat during a conflagration.
In this way the beam is completely encircled with air, and metallic connection
where a high temperature is most likely to prevail during a conflagration, is
practically avoided.
It will be understood that the Specification and accompanying drawing describe
and show the various methods by which I carry out my invention, but that the
details of drawings are to no particular scale, and that the dimensions and form of
any portion, or of the whole, may be modified as found necessary within the scope
of my invention.
い
I do not claim as my invention the use of corrugated iron to form centering or
of metallic lathing for ceilings-or of the use of plastering mortar on metallic
lathing.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is-
1st. In the construction of fire proof and fire resisting floors and ceilings, a
concrete floor supported on burnt clay or concrete blocks similar to the shape and
form shown, and upon corrugated iron arranged as described and shown, the
whole supported by steel or iron joists, practically as shown and described.
2nd. In the construction of fire proof and fire resisting floors and ceilings,
suspending ceilings by metal hangers in various ways to entirely separate and
divide the floor and ceiling; practically in the way shown and described.
3rd. In the construction of fire proof and fire resisting floors and ceilings, the
*complete encasement of bottom flanges of metal joists.
4th. The formation of a floor without the permanent use of corrugated iron
centres, or of supports or scaffolds erected from below, practically as shown and
.described.
5th. In the construction of fire proof floors and ceilings the complete encasement
of compound joists or girders projecting below the general ceiling line, practically
in the way shown and described.
6th. In the construction of fire proof floors and ceilings the combination of
concrete, metal flange shields, metal hangers, corrugated iron, and metallic lathing
and lathing bars to form fire resisting floors, practically as shown and described.
Dated this 30th day of April 1894.
THOMAS POTTER.