Side outlet device for a box gutter rainhead

A side outlet device suitable for use in combination with a rainhead to form an overflow assembly is adapted to enable the rainhead to be mounted external to the building in relation to a wall of the building, to one side of a box guttering extending interiorly along the wall, whereby water flowing from the roof is able to pass through the side outlet device to a downpipe via the overflow device. The side outlet device has a respective end section at first and second opposite ends, with the first end section having a form corresponding to the form of a box gutter end section such that, with the side outlet device mounted in relation to the wall, the first end section extends through the wall and is receivable in the gutter receptor of the overflow device. The second end section is adapted for connection to the box guttering to enable water to flow from the box guttering and through the side outlet device to the overflow device.

FIELD OF THE INVENTION

This invention relates to a side outlet device suitable for use with a rainhead overflow device for a box guttering system.

BACKGROUND OF THE INVENTION

The Australasian Standard AS/NZS 3500.3:2015 (‘3500.3 Standard’) Stormwater drainage code (titled Plumbing and drainage Part 3 Stormwater drainage) specifies and provides a respective illustration of three types of overflow device for box gutters, namely (a) a rainhead, (b) a sump/side overflow device and (c) a sump/high capacity overflow device. That 3500.3 Standard, as well as each subsequent edition specifies, in relation to a type (a) overflow device, that:

Rainhead denotes “A collector of rainwater, generally of rectangular shape, at the end of a box gutter and external to a building, connected to an external downpipe. It has a similar function to a sump.”

In contrast, the 3500.3 Standard and subsequent editions specifies, in relation to each of type (b) and (c) overflow device, that:

Sump denotes “A collector of rainwater, generally of rectangular shape, in the sole of a box gutter and connected to a downpipe within the building perimeter. Its function is to increase the head of water at the entry to the downpipe and thus increase the capacity of the downpipe.”

When a blockage occurs in a downpipe to which a rainhead is connected, the rainhead is intended to operate without an increase in the depth of water flow in the box gutter, even if operating up to its maximum design hydraulic capacity. Rather, water is required to overflow a wall forming a weir at the front of the rainhead and discharge to atmosphere. In contrast, a blockage that occurs in a downpipe to which a sump, of either type (b) or (c), is connected requires an increase in the depth of flow in the box gutter, up to the maximum design hydraulic capacity of the box gutter, in order for the sump device to allow overflow to occur. Thus, apart from some similarity in function, a rain head is installed and operates in a different manner to a sump.

A sump typically is mounted in the sole of the box gutter, between successive lengths of the gutter, and on roofing within the perimeter of a building. In contrast, a rainhead is typically external to the building, above an external downpipe. Specifically, the rainhead is mounted on an external wall of the building, adjacent to the perimeter of the roofing and at an end of the box gutter.

The present invention is directed to providing a side outlet device suitable for use with a rainhead overflow device for a box guttering system that facilitates the use of a rainhead in an increased range of applications. In combination with a rainhead, this invention provides an alternative to the sump/side overflow device of 3500.3, except that the downpipe is located on the outer face of an external wall of a building, rather than on the inner face.

BROAD DESCRIPTION OF THE INVENTION

According to a first aspect of the present invention, there is provided a side outlet device suitable for use in combination with an overflow device comprising or consisting of a rainhead to form an overflow assembly; wherein the side outlet device is adapted to enable the rainhead to be mounted external to the building in relation to a wall of the building, to one side of a box guttering extending interiorly along the wall, whereby water flowing from the roof is able to pass through the side outlet device to a downpipe via the overflow device; and wherein the side outlet device has a respective end section at first and second opposite ends, with the first end section having a form corresponding to the form of a box gutter end section such that, with the side outlet device mounted in relation to the wall, the first end section extends through the wall and is receivable in the gutter receptor of the overflow device, and with the second end section adapted for connection to the box guttering to enable water to flow from the box guttering and through the side outlet device to the overflow device.

In a first form, the side outlet device has a channel shape in cross-sections between the opposite ends defined by a base and opposed side walls upstanding from the base and joined across the first end by an end wall upstanding from the base, with at least one of the side walls having a region with a reduced height above the base to define an opening in which an end section of a length of box guttering is laterally receivable. In a second form, each of the side walls has a region with a reduced height above the base to define an opening in which an end section of a respective length of box guttering is laterally receivable. In each of the first and second forms the end wall may have a reduced height above the base, between the side walls, to define an opening in which an end section of a length of box guttering is receivable towards the second end.[009] According to a second aspect of the present invention, there is provided an overflow assembly including:

(a) an overflow device comprising or consisting of a rainhead; and

(b) a side outlet device enabling the rainhead to be mounted external to the building in relation to a wall of the building, to one side of a box guttering extending interiorly along the wall, whereby water flowing from the roof is able to pass through the overflow device to a downpipe;
wherein the side outlet device has a respective end section at first and second opposite ends, with the first end section defining a box gutter end section that, with the outlet device mounted in relation to the wall, extends through the wall and is receivable in the gutter receptor of the overflow, and with the second end section adapted for connection to the box guttering to enable water to flow from the box guttering and through the side outlet device to the overflow device.

In each of the first and second aspect of the invention, the overflow device most preferably is an overflow device comprising or consisting of a rainhead, for enabling water from the roof of a building and draining into and along a box gutter to flow into an external downpipe of the building, wherein the overflow device is adapted to be mounted external to the building in relation to a wall of the building, adjacent to a box gutter end, such as a box gutter end section extending through the wall, to enable water flowing from the roof to pass through the overflow device to the downpipe; wherein the overflow device is a rainhead comprising:a tub member having an inlet at an upper extent of the tub member,
an internal receptacle in the tub member, and
a chute provided in the tub member,
wherein the tub member further includes:a lower extent at which the tub member defines both a bottom wall at which the receptacle is adapted or adaptable to be connected to a downpipe and a chute outlet;a side at which the receptacle is adapted to be installed in relation to an external wall of a building, between an end of a box gutter section of guttering and an upper end of a downpipe of the building, whereby water from the box guttering is able to flow into the receptacle through the inlet and discharge through the bottom wall to the downpipe; anda wall that is common to the receptacle and the chute whereby, in the event of a blockage restricting the discharge of water through the bottom wall, water is able to rise in the receptacle to overflow an upper edge of the common wall and to discharge substantially vertically in the chute and to drain through the chute outlet.

In each of the first and second aspects of the invention, the side outlet device can have any of five different forms, depending on the manner in which, relative to a horizontally disposed line extending between the opposite ends of the side outlet device, the second end section of the side outlet device is adapted to receive water from box guttering, at the second end section of the outlet device. In a first form, the side outlet device is adapted to receive of second end section of the side outlet. In second and third forms, the side outlet device is adapted to receive water only from a single box gutter section communicating with one or other of those sides. In fourth and fifth forms, the side outlet device is adapted at the second end section to receive water from each a first box gutter section communicating with one or other of those sides, as well as from a second box gutter section communicating along the horizontally disposed line.

The overflow device of the invention may operate in a similar manner to the prescribed rainhead illustrated in 3500.3 Standard (herein the “prescribed 3500.3 rainhead”). Under normal flow conditions up to the design hydraulic capacity of the box gutter, stormwater is able to discharge into the downpipe to which a rainhead is connected, and from the downpipe to flows unimpeded to an authorised point of discharge for the building via an underground stormwater drainage system. However, the overflow device of the invention differs significantly from the prescribed 3500.3 rainhead in that:

a) The weir formed by the internal wall in the overflow device is concealed by the external wall, such that the weir is internal and not visible;

b) If the downpipe is blocked, or its flow capacity is exceeded, water first overflows the internal, non-visible weir, potentially impacting with the external wall before discharging down to atmosphere through the chute outlet at the bottom of the rainhead. This is in contrast to the prescribed 3500.3 rain head, as the latter causes the water to overflow the outer face of a front wall, comprising an external, visible weir, and thereby discharge to atmosphere; and
c) As a consequence of the external wall of the overflow device, water overflowing the weir is redirected so as to have an almost downwards trajectory by the time it reaches then bottom of the overflow chute. In contrast, the prescribed 3500.3 rainhead, the overflowing water has an initially horizontal trajectory that alters increasingly beyond the weir to downwards, due to the force of gravity (that is, it has a trajectory similar to water spilling over a waterfall or spillway). In this regard, the chute defined between the internal wall and the external wall spaced from the internal wall accords substantially with the usual meaning of denoting a channel or passage enabling unimpeded flow, such that the chute outlet most preferably provides no impediment, or at least minimal impediment, to such flow.

In addition to differences a) to c), the overflow device of the invention, at least in preferred forms, enables a secondary overflow provision. The latter provision is by an outlet or opening (typically rectangular, but other shapes, such as circular may be used) that is provided in the external wall and has sufficient capacity to operate as a supplementary overflow facility. However, it is likely to require extreme conditions, of both the downpipe and internal receptacle on the one hand and the weir and chute overflow provision on the other hand to be blocked, before such supplementary facility will be required. The overflow device is preferably proportioned such that the chute has adequate, or more than adequate hydraulic capacity, to discharge the water for the maximum design flowrate in the box gutter and rainhead. However, the overflow device could also be proportioned to have a relatively narrower chute, which would result in the primary overflow having a hydraulic capacity less than the design maximum flowrate, with the deficit in hydraulic capacity of the primary overflow then being provided by the secondary overflow. Most commonly, however, the primary overflow would be designed to have adequate, or more than adequate, hydraulic capacity, and the secondary overflow would not be required hydraulically. However, the secondary overflow could still be installed within the device for aesthetic reasons.

In addition to these differences, the overflow device of the invention is considered to have a significant aesthetic advantage over the prescribed 3500.3 rainhead as the spacing between the internal and external walls that forms the chute effectively hides the end of the box gutter and the weir, other than a small portion that may be visible if an outlet/opening is provided in the external wall to enable a supplementary overflow facility. The overflow device of the invention is considered to be visually preferable device, and hence more likely to be selected by architects, building designers, building owners, developers, plumbers and the like, over a rainhead like the prescribed 3500.3 rainhead.

The overflow device of the invention has a further substantial advantage in facilitating visual inspection from below (typically at ground level), as compared to commonly available rainheads. A check of whether the primary overflow outlet is blocked or clear can be conducted quickly and easily by an untrained person. As long as the primary overflow remains visually clear, the overflow device of the invention will continue to operate as intended in protecting the building from internal flooding. This is unlike previously proposed rainheads that requires access to the rainhead itself, or above it, for inspection purposes. Thus, the invention has substantial Occupational Health and Safety benefits in association with routine maintenance and inspections.

A downpipe is able to drain water from the internal receptacle by engagement of the upper end of the downpipe with the outlet provided in the base wall of the tub. The outlet preferably is preformed and of a size suited for engagement with a downpipe of a standard size. However, the outlet may be formed on site to suit a previously installed downpipe where there is a need to allow an installer the option of cutting an outlet hole to fit a particular size or location of downpipe.

The top of the internal wall most preferably is lower than the bottom of the inlet. The top of the internal wall also may be lower than an upper edge of each of opposite sides of the overflow device that extend from the mounting wall to the external wall, and also lower than an upper edge of the external wall. An upper edge of the internal wall that enables it to form or function as a weir may be sharply edged or rounded. The secondary overflow outlet, if provided, may have a bottom edge that is lower than the top of the internal wall, such as by about 25 mm or more.

Assuming that there is no blockage, the internal receptacle during normal flow conditions up to the design flow rate should be large enough to receive all water flowing through the inlet from a box gutter without the receptacle overflowing.

When the overflow device is used in conjunction with the side outlet device, the resultant overflow assembly enables use of the overflow device essentially in the usual manner, by the side outlet device adapting flow laterally with respect to box guttering. For this, the second end section may be adapted for connection to the box guttering at one or other of opposite sides of the second end section that are spaced laterally with respect to the spacing between the first and second ends of the outlet device. Thus, as viewed from the first end, the outlet device may have a left hand form or a right hand form, for receiving water from a box guttering extending laterally to the second end section of the outlet device from the left or from the right, respectively. However, the side outlet device may have a third form able to receive water from respective box gutterings, one guttering extending laterally to the second end section of the outlet device from the left and the other guttering extending similarly from the right. Also, as detailed earlier herein other arrangements are possible.

In order that the invention may more readily be understood, description now is directed to the various embodiments of the invention illustrated in the accompanying drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

With reference toFIGS. 1 to 6, there is shown an overflow device10, comprising or consisting of a rainhead, according to a first aspect of the present invention. InFIG. 1, the device10is shown as installed in relation to a building represented only by a section through a parapet wall12, an adjacent wall13and part of the structure of roofing14, for enabling water from the roofing to drain along a box gutter16on the roofing14. In the arrangement ofFIG. 1, the device10is mounted externally of the building on wall12, adjacent to a corner of the building defined by walls12and13, with the gutter16extending along the wall13. As seen inFIG. 1, the device10is mounted on wall12adjacent to an end of the box gutter16that extends through a purpose-cut opening18through wall12. The arrangement enables water to flow from the gutter16into an external downpipe20of the building, via the overflow device10.

The overflow device10comprises a tub22that includes a rear mounting wall24, an internal wall26and a base portion28. The arrangement is such that the tub22defines an internal receptacle30above the base portion28, between mounting wall24and internal wall26and also between sidewalls32each of which extends between a respective edge of walls24and26. The internal wall28forms a weir and the arrangement is such that water accumulating in receptacle30is able to overflow the upper edge of wall26when the hydraulic capacity of the receptacle30and downpipe20is exceeded, or when either the receptacle30or downpipe20is blocked, or partially blocked (thereby reducing their hydraulic capacity). However, the base portion28defines an outlet33adapted for engagement with the upper end of downpipe20for the intended purpose on water draining from receptacle30through the downpipe20rather than overflowing the weir provided by wall26.

The overflow device10further includes a front, or external wall34spaced forwardly from the internal wall26and joining across extensions of the sidewalls32. The arrangement is such that a chute36is defined between walls26and34and between sidewalls32, with the chute36having a chute outlet38defined by the internal wall26, the external wall34and the sidewalls32. Thus, in the event that water does overflow the weir provided by wall26, the water is able to discharge substantially unimpeded under gravity, through the chute36and the chute opening38.

The upper extent of mounting wall24is shaped to define, or is provided with, a gutter receptor40that forms an inlet41to the receptacle30. As shown, the gutter receptor40forms a rectangular opening42in the upper extent of the mounting wall24with a horizontally extending flange44projecting from the lower edge of the opening42, away from the internal wall26, with a respective upright flange46extending similarly away from each side of the opening42. The arrangement is such that the opening42and flanges44and46define the inlet41and receptor40is adapted to receive the end of the box gutter16to enable water flowing from the end of the gutter16to discharge into the receptacle and then through the outlet33of base portion28and into downpipe20.

The internal wall26has an upper edge that defines a weir26a. The height of wall26is less than that of the external wall34and the sidewalls32, and preferably not more than the height of the flange44that extends from the lower edge of opening42in the mounting wall24.

The overflow device10is adapted to be mounted externally of the building, with rear wall24of the device10located against the building wall12. The device10is mounted at a location at which the device10is adjacent to an end section of the box gutter16that projects outwardly with respect to the roofing14, into an opening12aformed through the wall12. At that location mounting wall24of the device is adjacent or against the wall12of the building with the flanges44and46received inwardly into the opening12a. The arrangement is such that, within the opening12a, the end section of gutter16is engaged received in the gutter receptor40, with the receptor preferably shaped so that the channel shape of the gutter16is neat in the receptor40(apart from a small gap allowed for the installation of a silicone sealant), whereby, with the overflow device10so mounted, water is able to flow from the roof of the building to drain along the box gutter16to flow from the end of gutter, through the inlet41and into the receptacle30. Thus, the water is able to discharge through the outlet33defined by the base portion28, into the downpipe20, if the receptacle30and the downpipe20are unblocked. However, if one or each of the receptacle30and the downpipe20is blocked, or partially blocked, or if, during an extreme rainfall event (i.e. having an intensity greater than the maximum design rainfall intensity), the hydraulic capacity of receptacle30and downpipe20are exceeded, or if the hydraulic capacity of the storm water drainage system downstream of the rainhead and downpipe is exceeded, water is able to fill receptacle30so as to overflow the weir26a, to discharge through the chute36to overflow outside the building.

As indicated, the chute36is defined between walls26and34and between sidewalls32, with the chute outlet38defined by the internal wall26, the external wall34and the sidewalls32. The chute36is disposed upright, when the device is mounted as described, so that water is able to discharge through the outlet38, in the event that water does overflow the weir provided by wall26a, by the water passing through the chute36and the chute outlet38by substantially by unimpeded free-fall under gravity. Preferably the lower edge of at least the internal wall26is below the underside of base portion28so that the tendency for water to flow around the lower edge of wall26does not enable water to pass across the underside of portion28towards wall12. This arrangement provides a ‘drip edge’, and its purpose is to prevent the flow of water laterally along a horizontal external surface to a vertical external surface, down which the flow or water can result in (unwanted) staining and/or water damage.

As a precaution, should flow through both the internal receptacle30and the chute outlet38become blocked, such as by leaves or twigs or foreign objects, an overflow outlet48may be formed in the external wall34. The overflow outlet48may be provided at a level at which its bottom edge is below the level of the weir defined by the internal wall26, but above the calculated impact point of the free overflow from the internal wall7forming a weir. A more detailed explanation of the secondary overflow outlet34in the external wall34is provided earlier herein, prior to reference to the accompanying drawings.

A moulding49may be provided around the upper extent of the external wall34and the sidewalk32both to lend rigidity, and to improve the aesthetics, of the device10. To facilitate attachment of the rainhead to the side of the building, an attachment member50as shown inFIG. 5may optionally be provided in addition to the fixing lugs51.

The alternative construction shown inFIGS. 7 and 8is generally the same as that forFIGS. 3 to 6with the exception that the moulding49A is provided internally of the tub3.

The flow control or overflow device10comprising a rainhead may be constructed of any suitable material. It may be of a metal such as steel, stainless steel, COLORBOND or Zincalume protected steel, aluminium or copper. Alternatively, the device10can be made of a suitable plastics material. Also, while the illustrated embodiment shows external box-shaped forms of overflow device10, it is to be appreciated that while it usually is necessary for the mounting wall24to be flat, the sidewalls32and the external wall34may be curved or bent. Indeed, the sidewalls32may curve to merge into a curved front or external wall34. A variety of configurations can be adopted to suit practical needs or aesthetic requirements that do not affect functioning of the overflow device.

The relative dimensions of key features of the overflow devices described with reference toFIGS. 1 to 8of the drawings will preferably be according to the prescribed 3500.3 rainhead. The dimensions can be chosen to comply with the requirements of the Australasian Standard AS/NZS 3500.3:2015 and subsequent editions, but are not limited to so complying. Those requirements require that the rainhead is physically sealed to the box gutter and has provision to overflow outside the building without restriction in up to a 1-in-a-100 year rain event. The rainhead may be sized to be slightly wider than the box gutter that it is servicing, such as to act as a cover plate around broken edges of masonry or render where the box gutter penetrates the outer wall of the building.

The actual sizes of the rainhead suitable for the particular application and location of use will be determined based on the design flow rate for a given roof catchment area having a design rainfall intensity for a 1-in-a-100 year reoccurrence for a specific location in Australia as defined in AS/NES 3500.3.

Currently AS3500.3 limits the maximum flow rate of all overflow devices to 16 litres per second. The dimensions of an overflow device comprising or including a rainhead desirably are based on both engineering design and aesthetic considerations. The dimensions are not required to be limited to any specific flow rate, and can be designed (by engineering principles and/or physical testing) to accommodate substantially larger flow rates that the maximum of 16 litres per second currently prescribed by 3500.3.

The following equations are utilized to compute the nappe profiles downstream of a box gutter, and of the internal wall26, respectively. Downstream of the Box Gutter (Free Overfall)—SeeFIG. 9:

y=heh0-Vu⁢yVu⁢x⁢X-gh02⁢Vu⁢x2⁢X2whereY=yh0heis the brink depthVuyis the vertical velocity component at the brinkVuxis the horizontal velocity component at the brink

X=xh⁢0h0is the uniform depth in the box gutterx and y are horizontal and vertical coordinates of the upper nappe respectively.

Downstream of the Internal Wall (Sharp-Crested Weir)—SeeFIG. 10.

y=(-0.4⁢2⁢5⁢(xH)2+0.055⁢(xH)+0.1⁢5+0.5⁢5⁢9)⁢Hwhere H is the upstream energy level (equivalent, in this case, to the upstream depth)x and y are horizontal and vertical coordinates of the upper nappe respectively.

Turning now toFIGS. 11 and 12, there is depicted a building60of which only roofing61, opposite left- and right-hand side parapet walls62L and62R, and a front parapet wall64, are shown. A central section64A of the front wall64is set back to form a U-shaped recess65between opposite, left and right side sections64L and64R of wall64, with the recess65having recess sidewalls65L and65R. Each side section64L and64R forms a front corner with a respective one of sidewalls62L and62R. As seen inFIG. 12, and the arrows “A” inFIG. 11, the direction of the flow of rainwater over the roofing61is perpendicular to and towards the sections of the front wall64. To accommodate drainage of the rainwater, the building has separate box guttering66extending along and against each section64A,64L and64R of front wall64, to provide a central box section66A and side sections66L and66R to the left and right of central section66A.

The section on line X-X ofFIG. 11is shown inFIG. 12, showing wall section64A of the building60, as well as the wall section621, in the background, roofing61and guttering section66A. Also shown are the overflow device10A comprising a rainhead, the side outlet device70A, while an overflow assembly72A comprises the combination of devices10A and70A.

Each guttering side section66L and66R has a highpoint68intermediate of its ends from which oppositely extending lengths of box guttering fall along the respective front wall sections64L and64R, to their outer ends. The outer-most length of guttering of each side section66L and66R has an end that projects into an opening in the respective sidewall62L and62R at which it communicates with a respective overflow device10L and10R. Each device10L and10R is in accordance with the first aspect on the invention and preferably corresponds with a device10as described with reference toFIGS. 3 to 6orFIGS. 7 and 8, and functions in relation to its box gutter length in the manner described for those overflow devices10. The arrangement is such that water is able to drain from the high point68of each side section66L and6R so as to drain through the respective one of devices10L and10R.

The inner-most length of guttering of each side section66L and66R extends from the highpoint68, along the respective front wall section64L and64R, to an end at a corner between its front wall sections64L and64R and a respective recess sidewall65L and65R. At that corner the innermost length of guttering terminates at a respective side outlet device70L and70R that projects into an opening in the respective front wall64L and64R. At that opening the outlet device70L and70R communicates with a respective overflow device10L′ and10R′. Each device10L′ and10R′ is in accordance with the first aspect on the invention and preferably corresponds with a device10as described with reference toFIGS. 3 to 6orFIGS. 7 and 8, and functions in relation to its side outlet device in essentially the manner described for functioning of each of those overflow devices10relative to its box gutter. Each side outlet device70L and70R is in accordance with the third aspect on the invention and preferably corresponds with a device later described herein with reference to the drawings. The arrangement is such that water is able to drain from the high point68of each side section66L and66R so as to drain through the respective one of devices10L′ and10R′. As will be appreciated, water flowing to device70L approaches from the left as viewed from in front of the building, while water flowing to device70R approached from the right. As a consequence, device70L is of opposite hand to device70R, such as due the devices70L and70R being mirror opposites.

The guttering central section66A has a low-point69intermediate of its ends to which each of oppositely extending lengths of box guttering falls from its outer end. The arrangement is such that water is able to drain to the low point69from each end of central section66A so as to drain through a side outlet device70A according to the third aspect of the invention, and then to discharge through an overflow device10A according to the first aspect of the invention. The side outlet device70A preferably corresponds with a device as later described herein with reference to the drawings and, as can be appreciated, it is can simultaneously receive water flowing from the left and right as the device70A is viewed from in front of the building. The device10A preferably corresponds with a device10as described with reference toFIGS. 3 to 6orFIGS. 7 and 8, and functions in relation to the side outlet device70A in essentially the same manner as described for the functioning of those overflow devices10relative to their box gutter section.

FIGS. 13 and 14provide similar perspective views of overflow device10A according to the first aspect of the invention shown in combination with a first form of a side outlet device70A according to the second aspect of the invention, to form a first form of an overflow assembly72A according to the third aspect of the invention.FIG. 15provides a perspective view of the overflow device10A apart from other components, while the side outlet device70A is shown inFIGS. 13 and 14, while a perspective view of a respective component of the side outlet device70A is shown in each ofFIGS. 16 and 17. As evident fromFIGS. 11 and 12, the overflow assembly72A ofFIGS. 13 to 17is suitable for use at a location such as shown at low-point69of guttering central section66A ofFIGS. 11 and 12. As depicted inFIG. 13, assembly72A is intermediate of end sections73of oppositely extending lengths of box guttering installed along the inner face of the central wall section64A of the external parapet wall64, such that water is able to drain along each length of box guttering to the low-point69, where the water is received into the side outlet device70A and then to pass through an opening74through the wall section64A, into overflow device10A to discharge under gravity via downpipe20A. The device10A preferably corresponds with a device10as described with reference toFIGS. 3 to 6orFIGS. 7 and 8, and functions in relation to the side outlet device70A in essentially the same manner as described for the functioning of those overflow devices10relative to their box gutter section.

The side outlet device70A may be of unitary construction formed as if from a single piece of appropriate sheet material, such as steel or other material detailed above. Alternatively, the device may be formed of an inlet section Y shown inFIG. 17and an outlet section Z shown inFIG. 16. As formed or assembled, the side outlet device has an open-topped, channel-shaped body75that extends between an inlet end75aand an outlet end75band is defined by a horizontally disposed base77and upstanding sidewalls78. At the inlet end75aof the body75the device70A has an end wall79that is upstanding from the base77and joins the sidewalls78. Over a distance from the end wall79, a part of the length of each sidewall78has a reduced height above the base77to form a rectangular opening80that is bordered by the end wall76, horizontally extending flange80aand an upright flange80b, with the flanges80aand80bof each sidewall78projecting outwardly away from the other sidewall78. The arrangement is such that each opening80, the end wall79and the flanges80aand80btogether define an inlet81that is adapted to receive the end of a respective box gutter section73to enable water flowing from each gutter section73to discharge into side outlet device70A and to flow therein from the inlet end75ato outlet end75b. From the outlet end75b, the water is able to flow into the overflow device10A and then to discharge via downpipe20A. To enable this, the body has a cross-section at the outlet that has substantially the form and dimensions of a box gutter for which the overflow device10A is designed to cooperate when used in the manner described with reference toFIGS. 3 to 6orFIGS. 7 and 8. Thus, the outlet end75bof the body75of the side outlet device70A can be received into the opening74through the parapet wall section64A and, within the opening74, the outlet end75bof device70A can be received and engaged in the receptor40A of device10A, so that water is able to flow from device70A to device10A. As will be appreciated, the flow through device70A to device10A is able to be received from both the left and right hand side of device70A, via respective box gutter sections73.

The base of the side outlet device77is set lower than the base (or ‘sole’) of box gutters73to an extent that relates to the hydraulic operation of the device77. AS3500.3 does not permit box gutters to change direction. However, the lower base of the side outlet device77creates a ‘knickpoint’ within the water flow, whereby free overran occurs from gutters73into the side outlet device77, allowing the side outlet device77to be considered as separate, deeper box gutter with water then flowing from the inlet end to the outlet end of the device77, and then into the downpipe via the overflow device comprising or including a rainhead, as previously described.

FIG. 18andFIGS. 19, 20, 21 and 22are similar toFIGS. 13 to 17, but show the overflow device10L′ in combination with a second form of the side outlet device70L to form a second form of overflow assembly72L. The device70L is suitable for use as the device70L in the arrangement ofFIGS. 11 and 12. In each case components of the overflow device10A or10L′ ofFIGS. 13 to 22correspond to components of the device10ofFIGS. 3 to 6and have the same reference numeral, such that duplication of description is not necessary. Rather it is sufficient to limit description to matters of difference between devices70A and70L and, hence, between overflow assemblies72A and72L. In the device70L, only one sidewall78has a reduced height above the base77to form a rectangular opening80that is bordered by the end wall76, horizontally extending flange80aand an upright flange80b, with the flanges80aand80bof the one sidewall78projecting outwardly away from the other sidewall78. As viewed from in front of the building ofFIG. 11, the one sidewall78with reduced height is the left hand sidewall78. The arrangement is such that the one opening80, the end wall79and the flanges80aand80btogether define a single inlet81that is adapted to receive the end of the inner-most length of guttering of side section66L to enable water flowing from the high point of that guttering to discharge into side outlet device70L and to flow therein from the inlet end75ato outlet end75b. From the outlet end75b, the water is able to flow into the overflow device10L′ and then to discharge via a downpipe for device10L′.

As will be appreciated, the device70R shown inFIG. 11can be the mirror image of the device70L and, as a consequence, it need not be separately illustrated. Again, in the device70R, only one sidewall has a reduced height above the base to form a rectangular opening that is bordered by the end wall, a horizontally extending flange and an upright flange, with the flanges of the one sidewall, the right sidewall in device70R, projecting outwardly away from the other or left sidewall. Again the arrangement is such that the one opening, the end wall and the flanges together define a single inlet that is adapted to receive the end of the inner-most length of guttering of side section66R to enable water flowing from the high point of that guttering to discharge into side outlet device70R and to flow therein from the inlet end to outlet end, and from the outlet end, the water is able to flow into the overflow device10R′ and then to discharge via a downpipe for device10R′.

As indicated, the side outlet devices can be of a unitary from, rather than made with two components as inFIGS. 13 and 18. However the two-component form is preferable for installing a side outlet through parapet wall (the most common scenario), whereas a single piece or unitary side outlet device would be difficult (although not impossible) to install. However, a single component side outlet could be utilised in for example a new build situation. A secondary benefit with a two-component form is that it can be expanded to fit various box gutter sizes using a single device (as long as the flow rate does not exceed the maximum capacity of the overflow device comprising a rainhead being utilised. In summary, it is generally easier to install the side outlet device as two components, particularly as box gutter sizes can vary quite considerably. In the case of a retrofit where lifting the box gutter is not possible, the side outlet can also be installed overlapping the box gutter or box gutter section, rather than being underneath them. Furthermore, a two-component side outlet device can be manufactured in one size, which adapts to different box gutter widths, whereas a one component side outlet would need to be manufactured in a number of different sizes, to suit different standard box gutter widths. Consequently, the two-component side outlet has benefits relating to the manufacture and stocking of one size only.

Turning now toFIG. 23, there is depicted a corner of a building160of which only two mutually inclined roofing sections161aand161bare shown in relation to adjacent side and front parapet wall sections162S and162F that together form the corner of the building. Roofing section161ais inclined down towards wall section162S, while section roofing section161bis similarly inclined down towards wall section162F. The arrows “B” inFIG. 23show the direction of the flow of rainwater over each roofing section161aand161bis away from a ridge R between the roofing sections161aand161b, and perpendicular to and towards the respective one of wall sections162S and162F. To accommodate drainage of the rainwater, the building160has separate box guttering166S and166F extending along and against the inner face of wall section162S and162F, respectively. Each guttering166S and166F has a fall towards the corner defined between wall sections162S and162F and, to enable drainage of water, an overflow assembly172, shown in detail inFIG. 24, is installed.

As can be appreciated fromFIG. 24, the form shown for the overflow assembly172is similar in most respects to the illustration inFIGS. 18 and 19of an overflow device10L′ comprising or including a rainhead in combination with a second form of the side outlet device170to form a form of overflow assembly172. Accordingly, a substantial understanding of the assembly172can be gained from the description ofFIGS. 18 to 22. Also, in a similar manner to device70L being of opposite hand to device70R, such as due the devices70L and70R being mirror opposites, it will be appreciated that the side outlet device170can be in a form that is the mirror image opposite of that shown. As with previously described side outlet devices, the device170has a rectangular opening180formed in one sidewall178, to enable engagement with an end of a laterally received box gutter section173. However, it additionally has a rectangular opening180′ formed in the end wall179to enable engagement with an end of a box gutter section173′ received at the inlet end175aat right angles to the gutter section173. The arrangement could be such that the opening is bordered by outwardly extending flanges corresponding to the previously described flanges such as80aand80b. However, the illustrated arrangement utilises a U-shaped bracket190that is sized to be a neat fit in the opening180′ and to receive the end of the gutter section173′. The web191and one arm192of bracket190has mutually perpendicular flanges191a,191band192a,192b, respectively, while the other arm193of bracket190has oppositely extending fore and aft flanges193a,193b. The overall arrangement of bracket190is such that sealing engagement is enabled with both the end175aof device170and the received end of gutter section173′.

FIG. 25depicts a front section of a building structure260having left and right hand building parts261and262, each with a front to rear external side parapet wall263and264and a common front parapet wall265of which left and right hand parts265aand265bform parts of building parts261and262, respectively. The building parts261and262may define a common internal space (not visible), or they may be at least partially internally separated from each other by a front to rear extending partition wall (not shown). The arrangement of structure260may be that of a pair of townhouses arranged side-by-side in a row and separated by a front to rear partition wall comprising a common wall or a double wall, while there may be more than two building parts in the row. Each part261and262has roofing266and267, each defining a front-to-rear roof ridge Ra and Rb and diagonal hips Ha and Hb.FIG. 25illustrates a good example of usage of the fourth and fifth forms of the second aspect of the invention and, while there are numerous other applications for both of these forms, the arrangement ofFIG. 25shows each of roofing266,267has:

(i) an outer side section266aand267athat slopes down from the respective roof ridge Ra, Rb to the respective side parapet wall263,264;

(ii) an inner side section266b,267bthat slopes down from the respective roof ridge Ra, Rb to define a front to rear valley “V” between the building parts261,262; and

(iii) a triangular front section (or roof ‘hip end’)266c,267cthat has an apex at the forward end of the respective roof ridge Ra, Rb and slopes down from hips Ha and hb to the front parapet wall265.

Each roofing266and267is such that that the flow of water during a period of rainfall is as illustrated by arrows “C”. Thus, rainwater flows down the respective sections of roofing266,267towards the side parapet walls263,264; into the valley V; and towards each part265a,265bof the front parapet wall265. Accordingly, the building structure260is provided with a box guttering system268having a respective box gutter section269aand269balong each of side parapet walls263and264; a further respective box gutter section271aand271balong each part265aand265bof the front parapet wall265; and a central front to rear extending box gutter270extending along the valley V. Each of gutter sections269and270has a fall towards a corner between the side wall263and264and a respective end of the front parapet wall265. Similarly the box gutter section270has a fall to the forward end adjacent to the front parapet wall265Each gutter section271aand271bhas a highpoint271cintermediate of its ends from which oppositely extending lengths of box guttering fall along the respective front wall part265aand265b. This arrangement is such that an outer one of the lengths of each section271aand271bfalls from highpoint271cto, and terminates at, a respective overflow assembly272,273at each corner between the respective front wall part265aand265band the respective side wall263and264, while the inner one of the lengths of each section271aand271bfalls from the highpoint271cto, and terminates at, a respective side of a further overflow assembly274; and gutter section270terminates at an inner end of assembly274.

Each of the overflow assemblies272,273and274comprises an assembly of a respective side outlet device272a,273aand274aaccording to the present invention with an overflow device272b,273band274bcomprising a rainhead. The arrangement is such that the side outlet device of each assembly enables water to able to pass through the parapet walls263,264and265, from the respective box gutter section, or sections and hence from within the parapet walls263,264and265, to discharge through a respective downpipe connected to each rainhead. Each rainhead272b,273band274bis mounted exteriorly of the building structure260and is as detailed above with reference to the rainhead ofFIGS. 3 to 6orFIGS. 7 and 8. As detailed above, and described later herein with reference toFIG. 26for assembly274, the respective devices272aand272b;273aand273b; and274aand274bcomprising the assemblies272,273and274are inter-connected through openings through the front parapet wall265, with each device273b,274band275bcomprising a rainhead mounted against the outer face of wall265. However, the assembly comprising devices272aand272bcorresponds to the assembly172ofFIG. 24, while the assembly comprising devices273aand273bis the mirror image opposite, or a version of opposite hand, of assembly172ofFIG. 24. Accordingly the detail of those assemblies will be understood readily from the description relating toFIG. 16. The arrangement is such the respective assembly of the devices272a,272bon the one hand and273a,2734bon the other hand could be reversed and installed so that each inter-connection is through one of the side parapet walls261,262with the rainhead mounted against the outer face of the respective one of walls261,262. The flow along the box gutter sections for discharge from each roofing266,267is depicted in each case by a respective arrow “D”.

FIG. 26shows a perspective view of the assembly274comprising the side outlet device274aand the rainhead274bof the building260ofFIG. 25. As indicated, the rainhead274bpreferably corresponds to the rainhead described with reference toFIGS. 3 to 6orFIGS. 7 and 8. Also, the side outlet device274areadily will be understood from consideration of the combined drainage requirements for roofing266and roofing267and description of the side outlet devices previously shown inFIGS. 13 and 24. As in the arrangement of side outlet device70A ofFIG. 13, the side outlet device274ahas opposed sidewalls278, each provided with a respective part of reduced height above the base277to form a rectangular opening280that is bordered by the end wall279to form a rectangular opening280. As inFIG. 13, the arrangement is such that each opening280, the end wall279and the flanges280aand280btogether define an inlet that is adapted to receive the end of a respective inner one of the lengths of each box gutter section271aand271bto enable water flowing from each of those gutter inner section271aand271bto discharge into side outlet device274aand to flow therein from the inlet end275ato outlet end275band through the rainhead274b. However, as in the manner of side outlet device170ofFIG. 24, the side outlet device274aadditionally has a rectangular opening281formed in the end wall279to enable engagement with an end of the box gutter section270received at the opening281at right angles to the gutter box gutter sections271aand271b. The illustrated arrangement utilises a U-shaped bracket290that is sized to be a neat fit in the opening280and to receive the end of the gutter section270. The web and one arm of bracket290has mutually perpendicular flanges291a,291band292a,292b, respectively, while the other arm293of bracket290has oppositely extending fore and aft flanges293a,293b. The overall arrangement of bracket290is such that sealing engagement is enabled with both the end275aof device274band the received end of gutter section270.

As will be appreciated, sealing engagement is required between interconnected components and devices, and between devices and box gutter sections, in accordance with established good practice. Thus, joints at interconnections preferably are riveted, such as at no less than 40 mm intervals in a staggered pattern. During assembly (and prior to the riveting) roof and gutter silicone should be applied between the jointed surfaces and compressed together using the rivets. Any excess silicone should then be wiped off and all rivets should be sealed up with silicone.

While the above description includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention.

It will be also understood that where the word “comprise”, and variations such as “comprises” and “comprising”, are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features.

The overflow device according to the invention that comprises or includes a rainhead has one or more features to facilitate overflow of water outside of a building even if a section of the rainhead becomes blocked. It also provides compliant overflow while maintaining a traditional rainhead aesthetic by means of the external wall of the rainhead able to shield against a direct line of sight into the end of the box gutter without impairing the ability of the rainhead to discharge overflow water if the rainhead outlet becomes blocked or if the flow of water is beyond the design capacity of the stormwater drainage system.