IMPROVEMENTS FLOORS AND ROOFS FOR WAREHOUSES, MILLS, AND OTHER BUILDINGS, MORE ESPECIALLY WITH A VIEW OF RENDERING THEM FIRE-RESISTING, AND IN MODES OF CONSTRUCTING THE SAME
Year: 1876

page_text: LETTERS PATENT to George Northcroft, of Liverpool, in the County of Lan-
IN
caster, Architect and Surveyor, for the Invention of "IMPROVEMENTS
FLOORS AND ROOFS FOR WAREHOUSES, MILLS, AND OTHER BUILDINGS, MORE
ESPECIALLY WITH A VIEW OF RENDERING THEM FIRE-RESISTING, AND IN
MODES OF CONSTRUCTING THE SAME."
Sealed the 23rd June 1876, and dated the 22nd April 1876.
PROVISIONAL SPECIFICATION left by the said George Northcroft at the
Office of the Commissioners of Patents on the 22nd April 1876.
GEORGE NORTHCROFT, of Liverpool, in the County of Lancaster, Architect and
Surveyor. "IMPROVEMENTS IN FLOORS AND ROOFS FOR WAREHOUSES, MILLS,
AND OTHER BUILDINGS, MORE ESPECIALLY WITH A VIEW OF RENDERING THEM
FIRE-RESISTING, AND IN MODES OF CONSTRUCTING THE SAME."
1st. The object of my Invention is to erect the floors and roofs of buildings as
indestructible as the walls and of similar kinds of materials, and thus prevent the
destruction of the said buildings by fire when the contents of one compartment
become ignited.
.
2nd. In carrying my Invention into effect, I construct the roofs and floors of the
buildings of fire-bricks or other blocks made of sufficiently fire-resisting materials
for the requirements of the case. These bricks are variously shaped, their mutual
support in the arch being usually aided by a series of projections fitting.into
corresponding recesses in the adjoining blocks. They are bonded with rolled iron
or steel, and form a series of compound flat arches, being arched in two directions
at right angles with each other. These arches are made in either one or two
thicknesses, but where two thicknesses (with a vacant space between) are used the
keystones and skewback bond through and tie both thicknesses together.
3rd. The compound arched floor is formed by dividing the space between the
end walls into a series of bays by means of rolled iron or steel girders filled in with
the flat arches, the skewback blocks of which entirely cover the top and bottom as
well as each side of the rolled girders. The arches are uniform throughout, the
soffit and crown being parallel to each other. The bricks are set in mortar, cement,
or fire-clay, but the girders are surrounded with an asphalt bedding, so that in case
[Price Gd.}

page_text: f
the floor got greatly heated the asphalt. would soften and allow the girder to
freely expand and contract. The crown and soffit can if desirable be grooved with
dovetail grooves to hold a concrete floor or a plaster ceiling, or both: The surface
of the floor can be, however, of any of the usual materials laid on the patent floor.
The ends of the arches and side skewbacks rest on a cast iron bond plate forming
a continuous tie round the building. Shoes are .cast to receive the ends of the
cast iron or steel girders which rest on-globes or rollers in the said shoes, constructed
so as to allow the said girders freedom of longitudinal expansion. The skewbacks,
keys, and bricks are, as said before, grooved and tongued into each other, and the
double skewbacks moulded so as to enclose between them the rolled iron beams.
In each groove I usually insert a bond of hoop iron vertically on edge running the
whole breadth of the room..
4. All the joints of the skewbacks, keys, and bricks are splayed or radiated on
the principle of an arch, whereby the vertical or downward pressure is at once
transmitted laterally by means of the double set of wedge-shaped keys acting at
right angles with each other. The beds of the tonguesrand grooves are, however,
level in all cases, and the back joints at right angles thereto.
When the walls of the building are brought up to an uniform level throughout,
I set on the cast iron band, securing the same with holding down bolts at each shoc.
I then build the arches on flat centering, first. I set the girders and skewbacks
next the keys, parallel-thereto;. I fill in the sides so as to complete the soffit, and
proceed to set the upper or crown course on a moveable centre, specially, made in
halves to slide on each other. No delay is occasioned to the progress of the build-
ing by the construction of, the floor. From the nature of the material, no injury
can arise through inclement weather, and. when together, it forms with the walls
a thoroughly homogenous structure equal in strength and indestructibility.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Northcroft in the Great Seal Patent Office on the 21st October
1876.
GEORGE NORTHCROFT, of Liverpool, in the County of Lancaster, Architect. and
Surveyor. "IMPROVEMENTS IN FLOORS AND ROOFS.FOR WAREHOUSES, MILLS, AND
OTHER BUILDINGS, MORE ESPECIALLY WITH A VIEW OF RENDERING THEM FIRE-
RESISTING, AND IN MODES OF CONSTRUCTING THE SAME."
1st. The object of my Invention is to erect the floors and roofs of buildings as
indest ructible as the walls and of similar kind of material, and thus prevent the
destruction of the said buildings by fire when the contents of one compartment
become ignited, and by regulating the thickness of the floor according to the size of
the building and material warehoused preventing goods in the adjoining compart-
ments being damaged by heat.
2nd. In carrying my Invention into effect I construct the roofs and floors of the
building of fire-bricks or other blocks made of sufficiently fire-resisting materials
for the requirements of the case. These bricks are variously shaped, their mutual
support in the arch being usually aided by a series of projections: fitting into
corresponding recesses in the adjoining blocks. They are bonded with rolled iron,
cast-iron, or steel, and form a series of compound flat arches, being arched 'in two
directions at right angles to each other. These arches are made in either one or two
thicknesses, but where two thicknesses (with a vacant space between) are used the
keystones and skewbacks bond through and tie both thicknesses together.
3rd. The compound arched floor is formed by dividing the space between the end
walls into a series of bays by means of rolled iron, cast iron, or steel girders filled in
with the flat arches, the skewbacks and blocks of which entirely cover the top and
bottom as well as each side of the girders. The arches are uniform throughout, the

page_text: :
soffit and crown being parallel to each other. The bricks are set in mortar, cement,
or fire-clay, but the girders are surrounded with an asphalt composite bedding so
that in case the floor got greatly heated the asphalt would soften and allow the
girder to freely expand- and contract. The crown and soffit can if desirable be
grooved with dovetail grooves to hold a concrete floor or a plaster ceiling, or both.
The surface of the floor can be, however, of any of the usual materials laid on the patent
floor. The ends of the arches and side skewbacks rest on a cast-iron bond plate
forming a continuous tie round the building. Shoes are set to receive the ends of
the rolled iron, cast-iron, or steel girders, which, rest on globes or rollers in the said
shoes, constructed so as to allow the said girders freedom of longitudinal expansion.
The skewbacks, keys, and bricks are, as said before, grooved and tongued into each
other, and the double skewbacks moulded so as to enclose between them the rolled
iron, cast iron, or steel beams. In each groove I usually insert a bond of hoop
iron, vertically on edge running the whole breadth of the room.
4th. All the joints of the skewbacks, keys, and bricks are splayed or raidiated on
the principal of an arch, whereby the vertical or downward pressure is at once trans-
mitted laterally by means of the double set of wedge shaped keys acting at right
angles to each other. The beds of the tongue and grooves are, however, level in all
cases, and the back joints at right angles thereto.
When the walls of the building are brought up to an uniform level throughout, I
set on the cast iron bond, securing the same with holding down bolts at each shoe.
I then build the arches on flat centering, first I set the girders and skewbacks
next the keys, both parallel and at right angles thereto, and fill in the sides so as to
complete the soffit, and proceed to set the upper or crown course on a moveable
centre specially made in halves to slide on cach other. No delay is occasioned to
the progress of the building by the construction of the floor. From the nature of
the material no injury can arise through inclement weather, and when together it
forms with the wall a thoroughly homogeneous structure equal in strength and
indestructible.
DESCRIPTION OF DRAWINGS.
Figs. 1, 2, and 3 are transverse views, and Fig.
forms of patent floor.
longitudinal section of various
Fig. 1 floor for warehouses, workshops, and other buildings of ordinary strength.
Fig. 2 floor for mansions, lighter workshops, or public or domestic dwellings.
Fig. 3 and 4, for warehouses, mills, or other buildings where great strength is
required. In these A, A, are the girders enclosed in skewbacks B, B; C, C, are the
keys; D, D, other bricks; E, E, walls; F, bond plate; G, roller and shoe supporting
girders; H, abutment on girder to assist walls in sustaining the arch; I, I, hoop iron
bond pieces; I, cieling; K, flooring of asphalt, concrete, or other material; L, timber
joist and flooring above fire-proof flooring; M, hollow airspace, which can if desirable
be filled in with concrete.
Having now described my Invention and the best mode known to me of carrying
it into effect, I wish it to be understood that what I believe to be new and desire to
claim under the herein-before in part recited Letters Patent is
1st. The arrangement or combinations of blocks splayed in both directions and
forming a compound arch for the purposes described.
2nd. The combination in floors or roofs of blocks with grooves and offsets and
iron bond embedded therein running the entire breadth, or nearly so, of the floor or
roof for the purposes described.
3rd. The combination of fire-proof flat arches and rolled or cast girders, with
metal skewbacks rivetted or bolted thereon, enclosed in the brickwork, yet free to
expand and contract with heat.
4th. The general arrangement of fire-proof floors (illustrated by Figures 3 and 4),
having two or more courses of brickwork with spaces between, jet connected by
keys or otherwise, so that the thickness of the floor can be varied according to the

page_text: size of the building and bulk of material to be sustained, and thus the heat be
prevented from radiating through from one compartment to another.
In witness whereof, I, the said George Northcroft, have hereunto set my
hand and seal, this Nineteenth day of October, in the year of our Lord
1876.
Witness
W. P. THOMPSON,
6, Lord Street, Liverpool,
British & Foreign Patent Agent.
GEORGE NORTHCROFT (18)