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

page_text: Date of Application, 27th Feb., 1893
Complete Specification Left, 19th July, 1893--Accepted, 19th Aug., 1893
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 relates to the use of terra-cotta, burnt fire clay or burnt common
clay tubes, or, for certain purposes, solid concrete fire resisting slabs, to form the
ceilings of apartments. These tubes and slabs are slotted at each end to enable
their upper portions to rest on the bottom flanges of rolled or wrought iron girders,
and their lower portions to cover, and thereby protect from heat, the bottom
flanges of the iron girders.
The unsupported portions of these tubes and slabs carry no weight, and are not
of the nature of a lintol or arch, but assume the character of cantilevers and are
thereby less liable to fall in case of fracture.
On each end of the tubes, or slabs, fire clay, common clay, or concrete blocks
are laid, which may be square or rebated, to receive corrugated iron sheets to form
centreing for the support of a concrete floor. This concrete floor may be finished
by any of the ordinary processes in common use. By the means described I form
ceilings entirely disconnected from the floors of apartments above, with the objects
of 1st preventing the passage of sound; 2nd, also of transmission of heat in case
of fire; and 3rd to provide a chamber for ventilation, gas pipes, electric light
wires &c.
1000
THOMAS POTTER.
COMPLETE 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 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 improvements in the construction of fire resisting floors
and similar portions of buildings, and is an improvement on a Patent granted me
on 7th January 1891-No. 291.
Instead of the usual system of making concrete, clay-tube, and other fire
resisting floors, solid, or in combination with a series of cavities formed in solid
floors, I entirely disconnect the upper or weight carrying portion of the floor, from
the under or ceiling portion of the room immediately beneath.
My object in doing this is to avoid the danger arising from the contraction of
the under side of fire resisting floors made of concrete and similar materials during
a conflagration, through the great heat arising therefrom and the expansion or
neutral condition of the upper portion of the floor by reason of the temperature at
that point often being reduced, or remaining normal, owing to the volume of water
thrown thereon. These two opposite forces result in the occasional breaking away
or dislodgement of portions of the underside of such floors. By entirely separating
the floor portion from the ceiling portion this element of danger is avoided.
Another object is to provide efficient means for ventilation, also for safe and
convenient places, easy of access but absolutely safe from fire and from interference,
for gas pipes, electric light wires, bell wires, cold water pipes, hot water pipes, &c.;
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page_text: also to lessen the great weight which is common to most fire resisting floors, and to
deaden sound.
According to my invention I employ iron or steel joists, usually of the section
shown by A Figures 1, 3, 4 and 5, but other sections may be adopted. I fix the
joists a certain distance apart, preferably two or more feet. I next fix hollow fire-
clay, common brick clay, or concrete tubes of the transverse section shown by C,
Figure 2, made of refractory materials, and having slotted ends, upon the bottom
flanges of the girders, so as to allow a portion to pass under the girder and protect
the latter from fire. Upon the ends of the tubes I bed with mortar, blocks or
bricks rebated or otherwise, and made of burnt clay or concrete, and I then lay
plain sheet metal or corrugated sheet metal on the blocks, or in the rebates of same,
to form a permanent centreing for ordinary concrete, which I deposit thereon and
this forms a floor. I make grooves on the under sides of the hollow tubes as shown,
to form a key for the plastering.
The surface of the concrete floor may be cemented, paved, tiled, or covered with
wood or other materials as may be desired.
Figure 1 is a cross section, and Figure 2 a transverse section of a fireproof floor
according to my invention; A is an iron or steel joist; B. B rebated blocks;
CC slotted tubes; D plain sheet metal or corrugated metal centreing; G concrete
floor; and a. a. Figure 2 cement grout run in between the tubes.
Figure 3 shows a variation of the same description of floor adapted_for_certain
places where hollow tubes to form a ceiling would not be available. I make solid
slabs of burnt clay, cement, concrete, plaster, or similar substances, and of a
peculiar form, having each end slotted to allow a portion to pass under the bottom
Hange of girder, and also leave an air space between the said slab and the said
bottom flange.
When necessary I suspend a plaster ceiling, using metal lathing with wire clips
or suspenders.
A is an iron or steel joist; B a rebated block; & concrete floor; D sheet metal
or corrugated metal centreing; H longitudinal section of a concrete or burnt
clay solid slab, 6 inches more or less in width; J an ordinary plastered ceiling;
E metallic fireproof lathing of any kind in common use; C air space between the
plastered ceiling and the solid slabs; and K wire suspender to carry the weight of
the hanging plaster ceiling. By this arrangement I obtain increased protection
from fire for the solid slabs and the iron girders.
Where unnecessary, the plastered ceiling may be dispensed with, and the solid
slabs form a ceiling of themselves and be exposed to view.
Figure 4 shows another variation of the same description of floor; I use solid
burnt clay or concrete slabs of a parallel thickness throughout, and kept in position
by bolts and nuts secured thereto, and to a bar of iron resting on the bottom flanges
of the girder. The slabs may be plain on the under faces, or they may have a
series of dovetail projections and recesses made therein to form a key to hold a
plastered ceiling, as shown on the hollow tubes C Figure 2. A is an iron or steel
joist; B a concrete or burnt clay block; C air space between ceiling slab and
bottom flange of joists to prevent the transmission of heat in case of fire; Da
metal bar; G concrete floor; H fireproof concrete slab; L L bolts or fangs to
hold up the ceiling M.
Figure 5 is an arrangement for forming a sloping floor for terraces, flat roofs, &c.
No increase of materials is required to obtain this slope or inclination, and a level
ceiling is provided for. I use iron or steel joists at certain distances apart, and by
gradually increasing the depth of the said joists I obtain whatever slope or inclina-
tion may be required. I adopt a form of ceiling which is, if desired, applicable to
either of the floors shown by Figures 1, 2, 3 and 4, in preference to those otherwise
described and shown on drawing.
I fix hangers made of stout sheet metal, preferably about one and a half inch
wide and one eighth of an inch thick, and which are kept rigidly in place by
concrete or burnt clay blocks. Through these hangers I make mortices near the

page_text: bottom, and I pass iron bars about three quarters of an inch wide and a quarter of
an inch thick through the mortices, for the purpose of fixing thereto metal lathing
(to hold a plaster ceiling) by means of wire ties. The object of this form of ceiling
is that it may be adopted in preference to those shown by Figures 1, 2, 3 and 4
where light weight, or economy in cost is desirable.
A is an iron or steel joist; B a block of burnt clay, concrete, or other material;
Cair space between ceiling and bottom flange of girder; D plain sheet or corrugated
metal centre; E metallic lathing; F plaster ceiling; G concrete floor; b. b. b. are
metal bars on edge and d. d. angle iron bangers through which the bars b. b. pass.
It will be understood that this Specification and accompanying drawing illustrate
the methods by which I carry out my invention, but that the disposition and form
of the materials and their arrangement may be modified, and the nature of the
materials may be varied as may be found necessary, within the scope of my
invention.
I do not claim as my invention the use of corrugated iron to form centres for
supporting concrete floors, nor of metal lathing for ceilings, nor of dovetail grooves
made in ceiling slabs, tubes, or blocks to uphold plaster ceilings, all of which are
well known and in common use.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the said is to be performed, I declare that what I
claim is,
1. In the construction of fire resisting floors, a concrete floor resting on blocks of
a square or other shape or rebated, and made of burnt clay or concrete, or other
material, supported by or connected to iron or steel joists practically in the way
shown and described.
2. In the construction of fire resisting floors, ceilings made of various materials,
and by different methods, entirely detached and separated from the floor over,
practically as described and shown.
3. In the construction of fireproof floors the formation of chambers between the
said floors and ceilings, substantially in the way described and shown.
Dated this 18th day of July 1893,
THOMAS POTTER.