Patent Publication Number: US-2019169865-A1

Title: Perimeter safety screen assembly

Description:
PRIORITY DOCUMENTS 
     The present application claims priority from: 
     Australian Provisional Patent Application No. 2016901878 titled “HANGING SCREEN” and filed on 19 May 2016; and 
     Australian Provisional Patent Application No. 2016904047 titled “A PERIMETER SAFETY SCREEN ASSEMBLY” and filed on 5 Oct. 2016; 
     the content of each of which is hereby incorporated by reference in its entirety. 
     INCORPORATION BY REFERENCE 
     The following publication is referred to in the present application and its contents are hereby incorporated by reference in its entirety: 
     International Patent Application No PCT/AU2003/001112 titled “A LIFTING OR TRANSPORTING MEANS USING A RECIPROCATING JACK” in the name of Formula One Self Driving Screens Pty Ltd. 
     TECHNICAL FIELD 
     The present disclosure relates to a perimeter safety screen assembly for a building. 
     BACKGROUND 
     Perimeter safety screens are generally employed to provide a screen or barrier at an edge of floors of a building which are under construction. 
     Desirably, a safety screen extends above the uppermost completed floor to protect workers preparing formwork for a new, higher floor of the building, and extends down to lower floors awaiting final fixing of windows or external walls. A key limitation to screen size however is the fact that these are typically delivered by a semi-trailer and then craned into position. This imposes limitations on the physical size of screens and/or screen sub-assemblies. 
     It is against this background and the problems and difficulties associated therewith that the present invention has been developed. 
     Certain objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed. 
     SUMMARY 
     According to a first aspect, there is provided a perimeter safety screen assembly for a building, the perimeter safety screen assembly comprising an upper screen assembly, and a hanging screen assembly appending from the upper screen assembly, and extending below the upper screen assembly. 
     In one form, at least one of the upper screen assembly or the hanging screen assembly is adapted so that the hanging screen assembly can be appended to, and removed from the upper screen assembly whilst the upper screen assembly is in use on the building. 
     In one form, the upper screen assembly is adapted so that the hanging screen assembly can append therefrom. 
     In one form, the hanging screen assembly is adapted to append from the upper screen assembly. 
     In one form, the hanging screen assembly depends from the upper screen assembly. 
     In one form, the hanging screen assembly extends from the upper screen assembly. 
     In one form, the upper screen assembly is a climbing screen assembly. That is to say, it is adapted to be raised with respect to the building, as work on the building progresses. 
     In one form, in an alternative, the upper screen assembly is not a climbing screen assembly, but one which must be repositioned by means external to it, such as a crane or a winch system. 
     In one form, the upper screen assembly comprises a base for securing the perimeter safety screen assembly with respect to the building, a frame depending from the base, and a screen depending from the frame. 
     In one form, the upper screen assembly comprises at least one platform inside of the screen and extending towards the building. 
     In one form, the upper screen assembly comprises a plurality of vertically spaced apart platforms. 
     In one form, the hanging screen assembly comprises a frame, and a screen depending from the frame. 
     In one form, each screen is comprised of a plurality of screen panels. 
     In one form, each screen panel comprises a frame and an infill panel. 
     In one form, the or each infill panel comprises a mesh. In an alternative, the infill panel comprises a solid panel. 
     In one form, the hanging screen assembly further comprises at least one platform inside of the screen and extending towards the building. 
     In one form, the hanging screen assembly comprises a plurality of vertically spaced apart platforms. 
     In one form, each of the platforms is either detachable, or movable between extended and retracted positions, to aid craning of the hanging screen assembly. 
     In one form, the hanging screen assembly depends from the upper screen assembly on an outer side (relative to the building) of the screen of the upper screen assembly. 
     In one form, in an alternative, the hanging screen assembly depends from the upper screen assembly on an inner side (relative to the building) of the screen of the upper screen assembly. 
     In one form, in an alternative, the hanging screen assembly depends from a lower edge of the screen of the upper screen assembly. 
     In one form, the screen of the hanging screen assembly forms a continuation of the screen of the upper screen assembly. 
     In one form, the upper screen assembly comprises at least one mount from which the hanging screen assembly can be suspended. 
     In one form, the upper screen assembly comprises a plurality of mounts. 
     In one form, the upper screen assembly comprises a plurality of vertically spaced apart mounts. 
     In one form, the or each of the mounts is located on an outer side of the screen of the upper screen assembly. 
     In one form, each of these mounts comprises a saddle for nestably receiving a portion of the hanging screen assembly. 
     In one form, the or each portion is a crossmember assembly for the hanging screen assembly. In this context, a crossmember assembly is a transverse assembly which adds support to the frame. 
     In one form, in an alternative, the or each portion is a crossmember for the hanging screen assembly. In this context, a crossmember is a transverse piece which adds support to the frame. 
     In one form, each of the mounts comprises an outwardly extending, upwardly angled (or hook-like) mounting guide for guiding one of the crossmembers into the saddle. 
     In one form, the or each of the crossmember assemblies comprises a length adjustment means. 
     In one form, the or each crossmember assembly comprises a central portion and a pair of adjustable end portions. 
     In one form, each of the end portions is movable between a retracted position and an extended position with respect to the central portion. 
     In one form, the screen for each of the upper screen assembly and the hanging screen assembly comprises a plurality of screen panel assemblies. 
     In one form, each of the screen panel assemblies comprises a width adjustment means. 
     In one form, the or each screen panel assembly comprises a central portion and a pair of adjustable side portions. 
     In one form, each of the side portions is movable between a retracted position and an extended position with respect to the central portion. 
     In one form, in an alternative, the arrangement of mounts and crossmember assemblies could be reversed on the upper and hanging screen assemblies. 
     According to a further aspect, there is provided a hanging screen assembly for a perimeter safety screen assembly for a building, the perimeter safety screen assembly comprising an upper screen assembly and the hanging screen assembly, where the hanging screen assembly is adapted to append from the upper screen assembly, and extend below the upper screen assembly. 
     According to a further aspect, there is provided an upper screen assembly for a perimeter safety screen assembly for a building, the perimeter safety screen assembly comprising the upper screen assembly and a hanging screen assembly, where the upper screen assembly is adapted so that the hanging screen assembly can append therefrom, and extend below the upper screen assembly. 
     According to a further aspect, there is provided a perimeter safety screen assembly for a building, the perimeter safety screen assembly comprising a first screen assembly, and a second screen assembly appending from the first screen assembly, wherein at least one of the first screen assembly or the second screen assembly is adapted so that the second screen assembly can be appended to, and removed from the first screen assembly whilst the first screen assembly is in use on the building. 
     For ease of description, a perimeter safety screen assembly embodying the present invention is described below in its usual assembled position as shown in the accompanying drawings, and terms such as front, rear, upper, lower, horizontal, longitudinal etc., may be used with reference to this usual position. However, the perimeter safety screen assembly may be manufactured, transported, or sold in orientations other than that described and shown here. 
     A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate by way of example the principles of the invention. While the invention is described in connection with such embodiments, it should be understood that the invention is not limited to any embodiment. On the contrary, the scope of the invention is limited only by the appended claims and the invention encompasses numerous alternatives, modifications and equivalents. For the purpose of example, numerous specific details are set forth in the following description in order to provide a thorough understanding of the present invention. 
     The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Embodiments of the present invention will be discussed with reference to the accompanying drawings wherein: 
         FIG. 1  is a schematic side view of a perimeter safety screen assembly according to a first embodiment; 
         FIG. 2  is schematic side view of a perimeter safety screen assembly according to a second embodiment; 
         FIG. 3  is a front view of the perimeter safety screen assembly of  FIG. 2 ; 
         FIG. 4  is a plan view of the perimeter safety screen assembly of  FIG. 2 ; 
         FIG. 5  is a schematic side view of a perimeter safety screen assembly according to a third embodiment; 
         FIG. 6  is an exploded side view of the perimeter safety screen assembly of  FIG. 5 ; 
         FIG. 7  is a front view of the perimeter safety screen assembly of  FIG. 5 ; 
         FIG. 8  is a plan view of the perimeter safety screen assembly of  FIG. 5 , further illustrating a hoisting frame assembly; 
         FIG. 9  is a detail view taken at ‘Detail  1 ’ in  FIG. 5 ; 
         FIG. 10  is a front view of the hoisting frame assembly illustrated in  FIGS. 8 and 9 ; 
         FIG. 11  is a plan view of the hoisting frame assembly of  FIG. 10 ; 
         FIG. 12  is a front view of a central portion of the hoisting frame assembly of  FIG. 10 ; 
         FIG. 13  is a plan view of the central portion of  FIG. 12 ; 
         FIG. 14  is a front view of an end portion of the hoisting frame assembly of  FIG. 10 ; 
         FIG. 15  is a plan view of the end portion of  FIG. 14 ; and 
         FIG. 16  is a detail view of an end plate from the end portion of  FIG. 14 . 
     
    
    
     In the following description, like reference characters designate like or corresponding parts throughout the figures. 
     DESCRIPTION OF EMBODIMENTS 
     Referring now to  FIG. 1 , there is shown a perimeter safety screen assembly  1  depending from completed floors  2  of a multi-story building which is under construction. 
     The perimeter safety screen assembly  1  comprises an upper screen assembly  50  which, in use, extends around a perimeter of the building and above the uppermost completed floor, primarily to protect workers preparing formwork for a new, higher floor of the building. 
     The upper screen assembly  50  comprises a screen  52  comprised of a plurality of screen panels  54 , where each screen panel  54  comprises a panel frame and an infill panel (of mesh in this case), and where each screen panel  54  depends from a frame  60 . In this embodiment, the frame  60  comprises a space frame structure of generally cuboid shape, and comprising a plurality of spaced apart frame posts  62 , which are bridged by a plurality of beams  64  and diagonal bracing struts  66 . 
     The frame  60  further comprises at least a pair of vertical bracket posts  70 . As seen in  FIG. 3 , each bracket post  70  is connected to, but spaced apart from, a frame post  62  by a plurality of joiners  68  that are evenly spaced along the length of the bracket posts  70  and frame posts  62 . The joiners  68  are narrower than the bracket post  70 . The result is a series of elongate slots formed between the bracket posts  70 , frame posts  62  and the joiners  68 . The function of these elongate slots will be described further below. 
     Each bracket post  70  is carried upon a bracket (also referred to as a shoe)  80  which depends from a horizontal support beam (also referred to as a needle or a base)  90  which in turn is secured with respect to the floor  2  slab. 
     Each of the brackets  80  comprise a pair of side plates that each have flanges on their forward edges that partly locate in front of each of the bracket posts  70 . One or each of the side plates are either hinged or can be separated to enable the brackets  80  to be secured to a bracket post  70 . 
     Each of the brackets  80  comprises a latch means that is designed to enable movement of the bracket posts  70  in only one direction with respect to each of the brackets  80 . The latch means (not illustrated) comprises a bar which is hinged to the upper edge of one of the side plates. The bar extends across the bracket  80  so that it rests on the upper surface of the opposite side plate. The bar is positioned so that it extends through the elongate apertures formed by the spacing of the bracket  80 , screen post  62  and the joiners  68 . 
     The frame  60  interposes the screen  52  and the bracket posts  70  so that the screen  52  of the upper screen assembly  50  is horizontally spaced apart from an edge of the completed slab  2 . In this way, the beams  64  of the frame  60  can provide support for one or more platforms (or walkways) formed by planks bridging these beams  64 . In this way, access is provided to the edge of the slab  2  that forms the floor. 
     The perimeter safety screen assembly  1  further comprises a hanging screen assembly  150  appending from the upper screen assembly  50 , and extending around a perimeter of the building, below the upper screen assembly  50  and down to lower floors awaiting final fixing of windows and/or external walls. 
     The hanging screen assembly  150  comprises a frame  60 , and a screen  152  comprised of a plurality of screen panels  154 . 
     In order to accommodate this hanging screen assembly  150 , the upper screen assembly  50  comprises a plurality of mounts  100  for the hanging screen  150 . Each of these mounts  100  comprises a saddle  102  for nestably receiving a crossmember  160  of the hanging screen  150 , and an outwardly extending, mounting guide  104  which is upwardly angled (or hook-like) for guiding one of the crossmembers into the saddle  102 . 
     In order to accommodate the mounts  100 , each of beams  64  of the frame  60  comprises a length of square hollow steel section. Each of the mounts  100  similarly comprises a length of square hollow steel section sized for insertion into one of the beams  64  of the frame  60  from an outerside of the screen  52  (relative to the building). Each of the beams  64  and the mounts  100  comprises an array of pin holes for receiving a pin (or bolt) to secure the mount  100  to the beam  64  of the frame  60 . 
     In use, the hanging screen assembly  150  is craned (using crane lift points) into position, and the mounting guides  104  will guide the hanging screen  150  into its saddles  102  on the mounts  100  as the hanging screen assembly  150  is lowered by the crane. The hanging screen assembly  150  will then partially overlap the upper screen assembly  50  on its outwardly (relative to the building) facing side at the lower end thereof. 
     The perimeter safety screen assembly  1  further comprises a means for lifting it with respect to the building. A detailed description of one embodiment of this means can be found in PCT/AU2003/001112, and is incorporated herein by way of reference at least. It should be understood however, that alternative lifting mechanisms may be employed, or that the external lifting means such as a crane or winch may be employed. 
     In one embodiment, the lifting means comprises two hydraulic cylinders (although these cylinders may be substituted with a power screw or mechanical jack), where each hydraulic cylinder extends from a beam  90  mounted bracket  80  at a lower end thereof, to a further bracket  80 , which is not beam  90  mounted, at an upper end thereof. Although two hydraulic cylinders are described, three or more hydraulic cylinders could also be used. In the case of two or more hydraulic cylinders, the important requirement is to achieve a reasonably equal rate of expansion of each cylinder. This is easily achieved by a person skilled in hydraulics. In addition, systems may be provided where a single hydraulic cylinder is used. In this case, additional support beams  90  may be spaced laterally of the hydraulic cylinder either at the same level as the hydraulic cylinder or above or below it. 
     In operation, as the hydraulic cylinder is expanding, the latch means on the bracket  80  on the upper end of the hydraulic cylinder will abut against the joiner and therefore lift the bracket post  70 . Upward movement of the frame will not be prevented by the remaining brackets  80 . The bar will hinge upwardly to allow the joiners to pass as required. 
     In use, when the bracket post  70  is moving upwardly, a joiner will eventually abut against the underneath surface of the latch bar. Continued upward movement of the bracket post  70  will result in the bar hinging upwardly and allowing the joiner to pass whereupon the bar will again hinge downwardly to rest on the upper surface of the adjacent side plate. The bar will prevent downward movement of the bracket post  70  when the joiner abuts against the upper surface of the bar. 
     At the maximum extent of expansion of the hydraulic cylinder, the joiners  68  are spaced such that a joiner  68  will have just have passed the latch means on the bracket  80  of the lower end of the hydraulic cylinder and the remaining brackets. Accordingly, contraction of the hydraulic cylinder will result in the bracket post  70  being held as the joiners abut against the upper surface of the bar on the bracket  80  on the lower end of the hydraulic cylinder. The latch means on the bracket  80  on the upper end of the hydraulic cylinder will operate to allow the bracket  80  to move downwardly with respect to the bracket post  70  until it reaches its lowermost position. Again, this may be designed so that it is conveniently placed in relation to a joiner so that upon commencement of the expansion of the hydraulic cylinder, the bar on the bracket  80  on the upper end of the hydraulic cylinder will again engage a joiner to resume lifting the bracket post  70 . 
     In this way, the bracket post  70  is conveniently lifted in relation to the support beams  90 . Obviously, a relatively short stroke hydraulic cylinder can be effectively used to lift the frame. 
     Once the lower edge of the screen reaches its uppermost position in relation to the support beam  90 , then it is a simple process to re-position the hydraulic cylinder to an upper level. As seen in  FIG. 2 , the hydraulic cylinder can be disconnected from the bracket  80  of its lower end. The upper bracket  80  is disconnected from the bracket post  70 . The lower bracket  80  continues to support the frame while the hydraulic cylinder is disconnected. 
     In order to provide additional support further beams  90  and brackets  80  may be secured at floors above or below the location of the hydraulic cylinder. 
     In use, the hanging screen assembly  150  will hang from and below the upper screen assembly  50 , and provide protection while workers complete the façade (amongst other things) of the building on lower floor levels. As the upper screen assembly  50  is raised, the hanging screen  150  hanging therefrom will be raised with it. 
     The hanging screen assembly  150  may further comprise one or more platforms or walkways  170  which extend from the frame  152  towards the building so as to substantially bridge the gap between these. 
     To facilitate the walkways  170 , the hanging screen assembly  150  comprises a plurality of walkway mounts  180 . Each walkway mount  180  comprises a bracket secured with respect to the frame  152  of the hanging screen assembly  150 , where each bracket comprises a socket for receiving an end of a walkway supporting beam  174  in a cantilever fashion. An array of bolt holes extends along each walkway supporting beam  174 , and in use, bolts can be passed through these holes to releasably secure the walkway supporting beam  174  with respect to the mounts  180 . 
     The mounts  180  are arranged in groups (which extend laterally across the hanging screen assembly  150 ), with each group spaced apart lengthwise along the frame  152  of the hanging screen assembly  150 . In this way, the walkways  170  can be positioned to match the floor levels of the building. 
     Additional stability for the walkways  170  can be provided by diagonal braces. One example of a diagonal brace  176  extends between the frame  152  of the hanging screen assembly  150  and the walkway supporting beams  174 , and a further example of a diagonal brace  178  extends between the walkway supporting beams  174  of vertically adjacent walkways  170 . 
     If necessary, the walkways  170  can be removed, or pivoted between open and closed positions, and the space which exists between the screen  152  and the edge of the floors  2  can be used to pass objects between floors  2 . In one example, a small crane can be employed to lower objects such as windows or cladding panels from an upper floor into an intended position on the side of the building, but inside of screen  152 , with the crane supporting the weight of the window or cladding panel while this is positioned and secured in place. 
     Referring now to  FIGS. 2 through 4 , where there is illustrated a perimeter safety screen assembly  1   a  according to a further embodiment. Those parts of the perimeter safety screen assembly  1   a  which are identical (or near-identical) to corresponding parts shown in the perimeter safety screen assembly  1  of  FIG. 1 , will be denoted by the same reference numerals and will not be described again in detail. 
     In perimeter safety screen assembly  1   a , the outermost frame posts  62  of the frame  60  for the screen  52  of the upper screen assembly  50  extend higher than the innermost frame posts  62 , so that the screen  52  may extend higher, thereby increasing the amount of protection provided for workers at the very top of the building. 
     Referring now to  FIGS. 5 through 9 , where there is illustrated a perimeter safety screen assembly  1000  according to a further embodiment. Those parts of the perimeter safety screen assembly  1000  which are identical (or near-identical) to corresponding parts shown in the perimeter safety screen assembly  1  of  FIG. 1 , will be denoted by the same reference numerals and will not be described again in detail. 
     The perimeter safety screen assembly  1000  comprises an upper screen assembly  1050 , which comprises a screen  1052  comprised of a plurality of screen panel assemblies  1054 . 
     With reference to each of  FIGS. 7, 8 and 9 , it can be seen that each screen panel assembly  1054  comprises a central portion  1054   a  and a pair of adjustable side portions  1054   b . Each of the side portions  1054   b  is movable between a retracted position and an extended position with respect to the central portion  1054   a . In the retracted position, the side portions  1054   b  either overlap or underlap the central portion  1054   a , and in the extended position, each of the side portions  1054   b  extends from a side edge of the central portion  1054   a . Moreover, in this embodiment, each of the side portions  1054   b  telescopes with respect to the central portion  1054   a . That is to say, each of the side portions  1054   b  is slidably received in a slot in a side edge of the central portion  1054   a . In this way, each screen panel assembly  1054  can be widened by extension of the side portions  1054   b , or narrowed by their retraction. By widening of screen panel assemblies  1054 , gaps between adjacent perimeter safety screen assemblies  1000  can be bridged. Narrowing of screen panel assemblies  1054  is useful during transportation and handling, and especially when craning these into an in use position, and lowering them from the in use position. 
     The perimeter safety screen assembly  1000  further comprises a hanging screen assembly  1150  appending from the upper screen assembly  1050 , and extending around a perimeter of the building, below the upper screen assembly  1050  and down to lower floors awaiting final fixing of windows and/or external walls. 
     The hanging screen assembly  1150  comprises a frame  1160 , and a plurality of the screen panel assemblies  1054  depending from the frame  1160 . That is to say, that each screen panel assembly  1054  comprises a central portion  1054   a  and a pair of adjustable side portions  1054   b . Each of the side portions  1054   b  is movable between a retracted position and an extended position with respect to the central portion  1054   a , as described above. 
     The frame  1160  for the hanging screen assembly  1150  comprises a pair of spaced apart elongate supports  1161 , from which all of the screen panel assemblies  1054  depend. 
     Referring now to  FIGS. 10 through 16 , where there is illustrated a crossmember assembly  2000 . The crossmember assembly  2000  comprises a central portion  2000   a  and a pair of adjustable end portions  2000   b . Each of the end portions  2000   b  is movable between a retracted position and an extended position with respect to the central portion  2000   a.    
     The central portion  2000   a  comprises a beam  2002  in the form of a length of square hollow section (SHS). Each of the end portions  2000   b  comprises a sleeve  2004  of SHS which is sized to slidably receive an end of the central portion  2000   a  (although this order could be reversed). Each of the end portions  2000   b  comprises a lifting lug  2006  extending from the sleeve  2004 , and the sleeve  2004  terminates at a mounting plate  2008 . 
     At or toward each end thereof, the central portion  2000   a  comprises an array of spaced apart holes  2010 ; similarly, the sleeve  2004  of each end portion  2000   b  comprises an array of spaced apart holes  2012 . In use, the position of each end portion  2000   b  with respect to the central portion  2000   a  can be adjusted, and then set by passing a suitable pin or bolt through aligned holes  2010  and  2012  in each of the central and end portions  2000   a  and  2000   b  respectively. 
     In use, one or more of the crossmember assemblies  2000  is extended and secured (by bolting and/or welding) between the spaced apart elongate supports  1161 . In use, the crossmember assemblies  2000  can be employed to hoist the hanging screen assembly  1150 , by attaching a crane hook with respect to the lifting lugs  2006 . Moreover, portions of the crossmember assemblies  2000  can be received in the mounts  100 , so as to hang the hanging screen assembly  1150  from the upper screen assembly  1050 . 
     The crossmember assembly  2000  is designed to be separable from the hanging screen assembly  1150  so that the number and position of crossmember assemblies  2000  can be adjusted and set as required to suit both weight and balance, and structural requirements of a particular installation. 
     The crossmember assembly  2000  is designed to be length adjustable to aid installation and removal, and also so that it can accommodate hanging screen assemblies of different dimensions (especially width). 
     Referring now to  FIG. 5  and Detail  1 , where there is illustrated a winch rail  1800  depending from the upper screen assembly  1050 . A winch carriage  1820  depends from the winch rail, and a winch depends  1840  from the winch carriage  1820  in turn. 
     The winch rail  1800  comprises an I-beam  1802 , which extends transversely across a lower edge of the upper screen assembly  1050 . The I-beam  1802  is bolted to the frame of the upper screen assembly  1050  via its upper flanges  1804 . 
     The winch carriage  1820  comprises a roller yoke arrangement comprising a body  1822  with a generally parallel flange cross-section. This parallel flange cross-section comprises a floor  1824  and a pair of parallel flanges  1826  extending upwardly from the floor  1824 . An inwardly directed roller  1828  is secured with respect to each of the flanges  1826 . These rollers  1826  are disposed either side of the I-beam  1802 , and so as to run along a lower flange  1806  of the I-beam  1802 . 
     An eye bolt  1830  extends through the floor  1824  of the parallel flange cross-section. The winch  1840  is suspended from this eye bolt  1830 . 
     The winch  1840  is used to lift panels from a lower floor. The panels would be stacked horizontally on the lower floor, and each panel is connected to the winch line and lifted vertically. The winch  1840  can move laterally along the winch rail  1800  to position the panel for fixing. 
     The hanging screen assembly  1150  may further comprise one or more platforms or walkways  170  which extend towards the building. Optionally, one or more of these platforms or walkways  170  may comprise a flap  190 , which is distal from the screen panel assemblies  1054 , and which is adapted to move between a closed position in which the flap bridges (and covers) a gap between the platforms  170  and the building, and an open position in which the gap is uncovered. When each of the flaps is opened, external windows or cladding can be lowered into position from above using the winch  1840 , and secured by workers standing on the platforms  170  inside of the safety screens. 
     The perimeter safety screen assembly according to the present disclosure provides a greater reach or range of screening, while overcoming difficulties associated with moving and assembling a larger screen. 
     Throughout the specification and the claims that follow, unless the context requires otherwise, the words “comprise” and “include” and variations such as “comprising” and “including” will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers. 
     The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge. 
     It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.