The Construction of Fire-resisting Concrete Floors and Ceilings Combined.
Year: 1891

page_text: Date of Application, 7th Jan., 1891-Accepted, 7th Feb., 1891
COMPLETE SPECIFICATION.
The Construction of Fire-resisting Concrete Floors and Ceilings
Combined.
I, THOMAS POTTER, of Grange Park, Alresford, in the County of 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 :—
The object and nature of my invention is the construction of fire-resisting
concrete floors, which shall consist of two distinct portions, viz. 1st. the floor or
weight carrying portion and 2nd. the under portion, forming also the ceiling of
apartment beneath, and divided from each other in the way shewn by accompanying
drawing, and which affords a space between them as a chamber for ventilation,
electric light wires, gas or water pipes &c. and to afford protection by the introduction
of cold air between the two portions of the floor in case of fire.
The separation
or division of the floor into two portions permits the under one to withstand
intense heat without disintegration, and consequent falling away,--and the upper
portion to be flooded with water without injury.
In the carrying out of my invention I employ ordinary concrete, made with such
materials as Portland cement, lime, gypsum &c. and broken or crushed pottery, bricks,
clinker, coke, or other materials of a like nature, and in the following manner, the
lower or ceiling portion of the floor marked C on drawing is cast in slabs of the
form shown, and when of sufficient hardness, the slabs are placed in position,
resting on the bottom flanges of iron girders, or on projecting courses of brick,
stone, or concrete, or in chases cut into the walls. On some occasions it may be
necessary and advisable to cast this ceiling portion of the floor in situ.
The upper, or floor and weight carrying portion D is formed by depositing
concrete in a soft state on a permanent centering of corrugated sheet iron, or
temporary wood centres. I do not confine myself to the exact contour of curved
lines, nor to the proportions and composition of the concrete, nor the size and shape
of the iron girders, nor their distance apart.
I do not claim any novelty in the form of the upper portion D of the floor, nor
for the use of corrugated iron for centering, but I claim as a novelty the principle
of constructing fire-proof concrete floors divided into two portions, or sections, the
upper being the weight carrying and the lower the ceiling portion, but combined,
so that with a minimum amount of materials they encase and protect the girders
from the effects of fire; and also the upper portion by compressing and rigidly
fixing each end of the ceiling or lower portions (where they rest on the flanges of
the girders) causes them to become of the nature of a cantilever, whose largest end
being immovably fixed enables the remaining portion to be upheld thereby, and in
case of fracture from fire, or otherwise, to remain in position without disturbance-
in the way described. To protect the bottom flanges of the girders I use asbestos
fire proof cement in the way shown on drawing, and where the girders may be of
unusual width I use wire netting fixed in a groove on each side in the concrete, to
form a key for asbestos cement as Fig. A; or the ceiling slabs themselves may be
made to cover each one half of the bottom flange of girder and join together as
Figure B.
Having now particularly described the nature of my said invention, and in
what manner the same is to be performed, I declare that what I claim is :-
1st. The invention of a fire-resisting concrete floor and ceiling combined, of a
peculiar form and principle, with space between the two sections thereof for the

page_text: admission of cold air, gas and water pipes &c. as shown by the accompanying
drawing.
2nd. The principle of upholding the lower or ceiling portion in case of rupture,
on the principle of the cantilever, in the way described and shown by drawing.
3rd. The encasing of the bottom flange of iron girder by using asbestos or
other fire-resisting cement in the way described and shown by drawing.
Deted this 6th day of January 1891.
THOMAS POTTER.