Note: Descriptions are shown in the official language in which they were submitted.
W093/20302 2 ~. 3 3 7 4 2 PCT/AU93/00156
Title: "LINTELS"
BACKGROUND OF THE INVENTION
(l) Field of the Invention
THIS INVENTION relates to lintels and, in
particular, to lintels made of concrete and the like.
(2) Prior Art
Lintels of various kinds are used in brick
walls to continue brickwork over the top of doors and
windows. Commonly the lintel is a length of angle iron
with the iron overlapped at its ends over the top of the
course of bricks at each side of a window or door
opening which finishes at the upper level of the door or
window. A variation of this style of lintel is seen in
US 4106247. The brickwork then continues with the next
course extended over the iron lintel. In time such
lintels are corroded particularly in environments such
as at the seaside. Concrete lintels are uæed, but ~or
these to have any long term stability against sagging,
they must be large in cross-section and they are
visually obvious witbin a ~rick wall llnless specially
treated with facing bricks. Large sectioned lintels in
concrete are heavy and not readily handled on a building
site.
OBJE~T OF THE INVENTION
It is an object of the in~ention to provide a
lintel which is basically relatively easy to handle on a
building site and, in use, resists sagging and corrosion
to a degree greater than hitherto possible.
NATURE OF THE INYENTION
The invention achieves its object by providing
a lintel for spanning openings such as windows, doors
and the like in a brick, block, or other like type wall
comprising:
an elongate body part ~ufficient in length
to span the opening with an upper surface for the laying
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of courses of bricks, blocks, etc. thereover;
characterised in that there is provided a
plurality of upstanding pins, posts or stops arrayed
along the length of the upper surface of the elongate
body part;
said pins, posts or stops being provided in
a predetermined pattern for projection into the perpends
between bricks or blocks laid, in use, over the lintel
to resist shear induced by the bricks thereover.
The term pins, posts or stops used herein is
to be taken to encompass any member which projects from
the surface of the lintel to project into the perpend
between bricks thereover and provide resistance to
shear. Thus pins, posts or stops (referred to for
convenience simply as pins or posts with the intention
that the broader function of a stop is to be read into
the term) might have a variety of geometries so long as
their shape is consistent with the need to project into
a~perpend and resist shear. A pin, post or stop might
therefore have planar, plate form characteristics and
still perform the invention by providing resistance to
` ~ shear at the top of the lintel.
The term bricks ox blocks used herein is to
include any block form construction wherein bricks or
the like are laid in courses with perpends therebetween.
Thus masonry and other block like constructions are
encompassed by the inventian where lintels are required
to support the construction over openings.
In use of the above defined lintels, the pins
or posts inter-engage with the bricks therebe~ween and
together with the weight of the courses above they
enable resistance to sagging of the lintel. By this
means the dimensions of the lintel may be reduced below
what would be otherwise necessary in a concrete lintel
~;~ 35 able to resist sagging of the lintel under the weight
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W093/20302 ~ 1 3 3 7 Q 2 PCT/AU93/00156
of bricks above.
It is believed that failure of a lintel
without pins is in part associated with failure of the
bond between lintel and bricks, which bond is especially
likely to fail when a damp proofing membrane is used
therebetween. The pins, posts or stops projected into
perpends opposes the shear stresses associated with this
failure. For a lintel to sag, the courses of bricks
above it must slide outwards relative to the lintel.
This outward movement exerts a force on the pins which
is resisted by the pins. The tendency to move outwards
is greatest towards the ends of the lintels and the
force required to be xesisted to prevent this movement
is also greatest towards the ends of the lintel. To
- ~ 15 resist this force, the number of perpends supplied with
pins or posts may be increased towards the ends of the
lintels. Conversely, the weight of the wall above a
lintel is believed to be loaded downwardly and outwardly
so as to load the bricks sideways against the pins,
posts or stops within the perpends between the bricks.
This outward loadins opposes the movement of the pins,
posts or staps which would be required if the lintel is
to sag. The weight of bricks over the lintel loads
outwardly such that a greater load is applied against
pins, posts or stops on the outer ends of the lintels
and the number of perpends supplied with pins, posts or
stops at the outer ends may be increased, or conversely,
the number of pins or posts at the centre may be
reduced.
3Q In one particular construction of the above
defined lintel, at each perpend to receive a pin or
post, the lintel may have two such pins or posts
projected therefrom, established by U-shaped elements
embedded in the lintel with their two arms projected
therefrom. The U-shaped elements may -be associated
W093/20302 2 1 ~ 3 7 ~ 2 PCT/AU93/001~6
within the lintel with an elongate length of reinforcing
rod embedded in the lintel as will become more clear
below.
BRIEF DESCRIP~I19~9~ AWINGS
S The invention will now be described with
reference to various preferred embodiments as shown in
the accompanying drawings, in which:
FIG. l is an elevation of a part of a brick
wall showing a lintel in accordance with the present
invention set in place;
FIG. 2 is a perspective section of a wall as
in FIG~ l;
FIG. 3 is a side elevation indicating a
pattern of pins or posts which might be used on a lintel
in accordance with the present invention in a wall of
the type illustrated in FIG. l;
FIG. 4 is a side elevation of an alternate
form for a lintel in accordance with the invention;
FIG. 5 is a vertical section through a wall as
in FIG. 2 showing details of a lintel in accorda~ce with
the present invention; and
FIG. 6 is a transverse section through a
lintel in accordance with the present invention showing
a lintel in accordance with the invention in greater
detail.
PREFERRED EMBODIMENTS
In FIG. l, a brick wall l0 is provided with a
lintel ll (shown cross-patched) over an opening 13 in
the wall l0. The lintel ll may be a cancrete lintel as
described below. It may be reinforced internally with a
length of reinforcement (not shown) embedded therein.
The wall l0 may be a brick veneer wall in a standard
form of dwelling. The preferred embodiments refer to
brick veneer and cavity brick constructions using
standard house bricks but the invention has application
~ Wog3/20302 2 13 3 7 l 2 PCT/AU93/00156
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in respect of all forms of brick and block construction.
The lintel is dimensioned with a cross-section which
matches that of a single course of bricks so as to mate
into the brickwork in a tidy fashion with an end which
overlaps the lower course of bricks at the sides of the
window as at 12 in FIG. 1. The length of the lintel is
normally equal to an even number of bricks and mortar
spacings therebetween.
In its preferred form, the lintel of this
invention is formed by concrete. In its usual form, it
requires some tensile reinforcement or tensile strength.
However, it will be clear to a man skilled in the art
that the mechanics of the pins or posts to be described
below will be realised no matter what the material of
the lintel might be. Conseguently, the invention should
not be interpreted to be restrictPd to concrete.
However, the ensuing description is with regard to the
:
use of concrete.
- As stated above, the lintel is able to be used
with brickwork, to support courses of bricks over doors,
windows, and the like. In cavity brick constructions,
a sepaxate lintel can be used in each wall of the double
wall of bricks, at the top of an opening to be spanned
by further courses of bricks.
FIG. 2 is a perspective view of a lintel 11
as in FIG. 1, at an end of the lintel. The lintel 11
has split bricks 38 applied thereto with mortar
imitating spacings therebetween such that the lintel
, merges with the wall when installed. The lintel
preferably has a reinforcement 39 extended through the
material of the lintel. A damp proof membrane 40 can be
used above the lintel and a sealant can be applied
between the damp proof membrane 40 and a top surface of
the lintel 11.
In FIG. 3, the lintel 11 is shown as it would
W093/20302 PCT/AU93/001~
21337~
lie in place in wall 10 without a course of bricks
thereabove. This way, the pins or posts 14 can be seen.
There may be pins or posts at each perpend to put a pin
or post between every pair of adjoining bricks, or,
S various perpends may be left without pins. As described
above, loading is downward and outward so that in the
region 16, every second perpend might be provided with a
pin or post, or no perpends (as will be described below)
may need to be provided with pins, and every perpend in
the regions 15 and 16 at the outer ends of the lintel
;~ 11 can be provided with pins. In a preferred form of a
lintel of the type illustrated in FIG. 3, if the width
of the opening is L then the centre region 16 width
might be ~L and the outer regions 15 and 17 might be
egual in length. Other designs besides this are
possible (see below). The length of the lintel will be
longer to some considerable degree to load the weight
above the lintel into the brickwork at each side of the
opening. With standard brick dimensioned lintels, a 600
mm opening might be spanned by a 960 mm lintel. A 3600
~- mm opening by a 4080 mm lintel. To avoid sagging of the
lintels, the longer lintels may require larger numbers
of courses over them to provide sufficient total cross-
section to resist sagging and to keep the shear stresses
in the mortar joints and on the pins to an acceptable
low level. For a 3600 mm opening a lintel of standard
brick cross-section and the above described pin or pos~
pattern, at least six courses of bricks will be likely
, to be required over the lintel to avoid its sagging.
The number of courses steadily drops to two when the
opening width is reduced to 2100 mm from the six at 3600
mm for lintels of the above type.
; In FIG. 4, the lintel 32 extends across a
space between walls 33 and 34 with shear pins 35 as
above except in this embodiment the centre 36 is free of
~ W093/20302 2 ~ 3 3 7 4 2 PCT/AU93/00156
shear pins. This is possible as the shear pins which
are most called on in realising the effect of the
invention are the outer shear pins, the ones towards the
ends of the lintel.
In FIG. 5, a roof truss 18 is shown over a
timber wall 19 with a brick veneer wall 20 spaced
therefrom over a lintel 21. The lintel 21 has a facing
brick 22 attached thereto so that visually the lintel 21
is hidden and the wall 20 appears to be continuous down
to the top of the opening over which lintel 21 extends.
Pins or posts 23 extend into the perpends of the next
course of bricks and wall 20 may be attached in the
usual way by suitable connectors or brick ties 24 to
frame 19 to bind the two elements of the wall. The wall
19 may be the usual load bearing stud wall. A damp
~;~ Proof membrane 37 may be fitted as shown.
In FIG. 6, the lintel 25 in concrete has a row
of facing bricks 26 applied thereto so that it merges
into the wall when in place. The upper surface 27 has
an array of pins or posts therealong at chosen i~tervals
and at each interval, the pins or posts may be U-
shaped elements 30 with their arms 28 and 29 projected
out of the upper surface to a degree which puts their
ends into the perpends of a course laid thereover. The
U-shaped elements 30 may be attached to a length of
reinforcement 31 inserted into the lintel at its
formation. The U-shaped elements and the reinforceme~t
may be welded together as a prefabricated assem~ly which
is held within the concrete of the lintel as the
concrete sets in a suitable mould. Of course, other
shapes besides U-shapes might be used. Pairs of
vertical pins are not the only geometry which could be
used. Single pins, loops and multiple posts might
project into a perpend so long as the resistance to
shear forces exerted by the courses over the lintel
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WOg3/20302 21 3 3 7 4 2 PCT/AU93/00156
exist. The pins may be eight gauge galvanised rod. The
reinforcement might be a length of galvanised Yl6 rod.
A welded assembly of rod stock to form reinforcement and
pins or posts is best galvanised after welding for
maximum anti-corrosive properties. The concrete lintel
is typically 85 mm deep with rod 31 set 40 mm therein
- from the top. The concrete lintel might be 97 mm wide
with a 20 mm facing brick set 7 mm therein at a front
face to duplicate full width brick. It wili be clear to
those skilled in the art that the dimensions will vary
to suit the application and particularly the nature of
the bricks or blocks being laid. The dimensions herein
are likely with conventional bricks.
Use of the above described lintel has
lS advantages over standard lintels such as improved fire
; rating in addition to sag resistance and corrosion
resistence. Performance of the lintel is enhanced in
usuage such as in FIG. 2 by the provision of weep holes
in the mortar above the damp proof membrane to enable
dràinage of moisture otherwise trapped above the
membrane.
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