EP4453346A1

EP4453346A1 - Back box mounting bracket and method for a stud wall

Info

Publication number: EP4453346A1
Application number: EP22757318.5A
Authority: EP
Inventors: Josue ESTRADA
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-12-21
Filing date: 2022-08-01
Publication date: 2024-10-30
Also published as: GB2603851A; GB2603851B; WO2023118776A1

Abstract

A bracket (8) is provided for securing a back-box into a hole (5) in a wall board (4) of a stud wall. The bracket (8) has a back limb (9), side limbs (10) extend perpendicular from the back limb one from each proximal end of the back limb. Each side limb supports a fixing part (11) extending from the distal end of the side limb, parallel and away from the back limb. Each fixing part (11) is adapted to receive and threadedly engage at least one drywall screw. In use during installation the bracket can be inserted through the hole so that the fixing parts bear against the back face of the wall board adjacent the hole. Drywall screws are driven through the drywall from the front into the fixing parts to secure the bracket. A back-box is then inserted into the hole and secured to the back limb using a drywall screw driven through, through holes provided in the rear panel of the back-box and into tap holes (9.1) provided in the back limb.

Description

BACK BOX MOUNTING BRACKET AND METHOD FOR A STUD WALL

Technical Field

[oooi] The present invention relates to the fastening of a metal back-box in a stud wall. A back-box provides a metal box of standardised dimensions into which mains electrical fittings such as switches and sockets are fitted. A back-box is received into a correspondingly sized hole cut into stud wall. A stud wall is a wall fabricated from a frame to which a wallboard, commonly plasterboard, is secured. The invention relates to the installation of a back-box in a stud wall during construction and on pre-existing stud walls.

Background

[ooo2] For compatibility with standard sized electrical fittings back-boxes come in standardised sizes of width and depth, The standard size of double gang back-box and therefore the hole is 70 X 140 mm, or for single gang back-box is 70X70mm, the standard depths of back-boxes is 25, 35 and 47mm.

[ooo3] The attached figures show a stud wall during construction. The wall is fabricated from a deck plate 1 , secured to the building floor. A head plate 3 is secured to the ceiling. Three vertical studs 2a, 2b, 2c are disposed upstanding between the deck plate and the head plate. A first wallboard 4 is attached to a first side of the studs using drywall screws or pins. This invention was initially developed to apply to a stud wall under construction and so only the first wall board is installed at this step, however the invention can be applied to a completed stud wall with a wall board applied to each side. Commonly the studs and plates are fabricated from wood or aluminium. A rectangular hole 5 is cut through the wallboard 4 at the desired location of the electrical fitting, this is usually measured and cut from the front or exposed side of the wall as shown in figure 1 . The tradesman then goes to the exposed back side of the wall and installs a noggin 6 which is a horizontal frame member secured at each end to adjacent studs 2b, 2c at a height to overlap the hole 5. The tradesman now returns to the front side of the wall to insert a back-box. The back-box is secured by self-tapping screws driven through holes provided in the rear panel of the back-box into the noggin.

[ooo4] Where aluminium noggins are used, as diagrammatically indicated, the noggin has a bracket formed at each end which overlaps the respective stud. Usually a second layer of wall board will be fitted over the “back” of the partition when wiring is completed and this bracket is found to commonly obstruct fitting the back wall board.

[ooo5] It is preferred to use metal back-boxes because they may be required to meet fire safety regulations and can be recycled when the wall is demolished or refurbished. Known back-boxes for flush fitting into a stud wall include a metal box having a rectangular rear panel, box walls including opposing side walls and top and bottom walls which are upstanding from the rear panel. Holes are stamped through the rear panel through which self-tapping screws can be driven to secure the back-box to a noggin. Circular kiss cut or partially cut knock out’s are provide which can be selectively knocked out of the walls or rear panel to provide for cable runs to the electrical fixture.

[ooo6] A plastics backbox is known which has features similar to the metal box, but formed in plastics and additionally includes a flange run around the front edge of the box walls to bear against the external surface of the wall board around the installation hole. The screw holes provided in a metal back-box are not provided, instead a clamp can be installed into each box side wall to clamp the wall board between the clamp and the flange and thus secure the back-box. Such boxes are slow and fiddly to install and rely entirely on the integrity of the wall board immediately adjacent the hole for security. Fabrication from plastics means they do not meet all fire safety standards. Also the flange has a significant thickness so that the electrical fitting will not fit flush to the wall surface, which is an undesirable finish.

[ooo7] It is an object of the present invention to provide a back-box bracket, a back-box and a method of installing the back-box which reduces the labour of installation at least when fabricating a stud wall and is capable of meeting all fires safety regulations.

Summary of Invention

First aspect

[ooo8] According to a first aspect of the present invention there is provided A back box mounting bracket comprising: a back limb; opposing side limbs extending one each from each proximal end of said back limb; each side limb extending to support a fixing part, each fixing part extending one from each distal end of each side limb, wherein each said fixing part extends to bear against the back surface of a wall board to be threadedly engaged by a self-tapping screw driven through the wall board each fixing part adapted by the provision of an array of tap holes (23) spaced by less than the half the radius of each tap hole, or by fabrication of the fixing part from a metal mesh, wherein the pitch of the mesh is more than the minor diameter and less than the major diameter of a metric standard drywall screw to receive and threadedly engage at least one self-tapping screw.

[ooo9] The brackets are provided in a range of sizes so that they can be selected for compatibility with a given standard sized back-box. In each case the back limb is sized to extend across the a back panel of a standard sized back-box with the back limb in at least partial engagement with the back of the back surface of the back-box.

[ooio] In an embodiment of the bracket the side limbs may have a gripping part adapted to grip on to the side walls of the back-box. The side limbs may be resiliently deformable such that the side limbs can be temporarily pulled relatively apart in order to insert the back-box and released so that the gripping parts press against the side walls to grip the back-box. The distance between at least a part of the side limbs is specified to be less than the distance between the outside surfaces of the side or end wall of a standard back-box, when the bracket is in a relaxed condition. The side limbs may be “S” shaped. The side limbs may have enhanced gripping surfaces provided by spikes or tooth formations disposed on the side wall gripping surfaces.

[OOH] A fixing part may be provided by a panel which extends from the distal end of the side limb remote from the back limb. Preferably the distance of the fixing part from the back limb is less than the depth of the back-box walls so that the fixing part can sit flush against the back surface of the wall board, while the front edge of the walls is flush or is recessed into the hole. The panel may be perforated with through holes to receive one or more securing fastening such as dry wall screws. The bracket can be made from fire resistant plastics material but is preferably manufactured from a single piece of metal, preferably steel, stamped or otherwise formed into the appropriate functional shape.

[0012] Preferably the bracket is configured so that it can be inserted through the hole cut for the back-box from the front of the wall and manually held behind the hole while a self-tapping screw is driven through the wall board, from the front face, adjacent the hole and into the fixing part. Once the bracket is secured via screws driven into each fixing part, the back-box can be inserted into the hole and secured to the back limb via another screw driven through a hole provided in the rear panel of the back-box and into the back limb.

Second aspect

[0013] According to a second aspect of the present invention there is provided a method of installing a back-box into a stud wall using a bracket according to the first aspect of the invention comprising the steps of: cutting a back-box sized hole in a wall board of a stud wall; manually holding the bracket, feeding the bracket through the hole and locating the each fixing part to press against the inside surface of the wallboard adjacent the edges of the hole; driving a screw from the outer surface of the wallboard, one each into each fixing part; inserting a compatibly sized back-box into the hole; driving a screw through the rear panel of the back-box into the back limb of the bracket whereby the back-box is secured in the hole. Third Aspect

[ooi4] According to a third aspect of the present invention there is provided a method of installing a back-box in a stud wall under construction at a stage where a single wallboard has been secured to the stud frame using a resiliently deformable back-box mounting bracket having a gripping part according to the first aspect of the invention, comprising the steps of: selecting a back-box and correspondingly sized mounting bracket; cutting a standard sized hole for a standard sized back-box through the wallboard; securing the mounting bracket to the back-box; inserting the back-box into the hole and securing the bracket and hence the back-box to the back surface of the wall board.

[0015] Under some circumstances the entire method may be performed from behind the stud wall obviating the time taken to move back and forth from the front of the wall to the back, the requirement for installation of a noggin is obviated together with the problems associated with any noggin bracket.

Fourth aspect

[0016] According to a fourth aspect of the present invention there is provided a back-box having a rectangular rear panel, opposing side walls, and opposing top and bottom walls, said walls upstanding from the edges of the rear panel, and a fixing part comprising at least one panel extending perpendicularly outwardly from the external surface of one or more of the walls, having a front surface spaced from the front edge of the walls, wherein the spacing corresponds to the thickness of a standard thickness of wall board. [0017] Preferably the fixing part is a panel extending normal to the side wall and parallel to the rear panel, perforated to receive fixings such as drywall screws, whereby it can be screwed to the back surface of a wall board adjacent the hole. Panels may extend from each wall to provide multiple opportunities to secure the back-box. Multiple fixing parts may be provided at different spacings from the front edges of the walls to accommodate different thicknesses of wall board. Unwanted and obstructive fixings may be adapted to be broken off of the box by the formation of kiss-cuts or partially perforated regions. Alternatively the fixing part may initially be a panel part cut out of at least one of the side walls adapted to be folded out of the side wall. The location of the fold may be selectable to correspond to standard thicknesses of wall board. Wall board is usually 9.5, 12mm or 15mm thick.

Fifth aspect

[0018] According to a fifth aspect of the present invention there is provided a method of installing a back-box according to the fourth aspect into a stud wall under construction at a stage where a single wallboard has been secured to the stud frame comprising the steps of: selecting the back-box; cutting a hole through the wall board corresponding to the size of the back-box; applying the backbox to the hole so that the front edge of the side walls is flush or recessed from the front surface of the wall board; driving a fastening through the fixing part into the rear surface of the wall board to secure the back-box. Brief Description of Figures

[0019] Embodiments of a back-box mounting bracket, a method of installing a back-box in a stud wall under construction at a stage where a single wallboard has been secured to the stud frame using a back-box mounting bracket, a back-box and a method of installing a back-box, in accordance with the present inventions, will now be described, by way of example, with reference to the accompanying figures, in which:

Figure 1 is a SE isometric view of the front of a stud wall illustrating a prior art back-box installation;

Figure 2 is a NE isometric view of a stud wall illustrating a prior-art back-box installation;

Figure 3 is a flow chart illustrating the steps of the prior art method of installing a back-box;

Figure 4 is a flow chart illustrating the method of installing a back-box according to a first aspect of the invention;

Figure 5 is a SE isometric view of the front of a stud wall illustrating a back-box of embodying the invention according to the first aspect;

Figure 6 is a NE isometric view of the rear of a stud wall illustrating installation of a back-box according to the first aspect of the invention;

Figure 7 is a plan view of a first embodiment of a bracket according to a first aspect of the invention;

Figure 8 is a NE isometric view of the bracket of figure 7;

Figure 9 is a plan view of the bracket of figure 7;

Figure 10 is a SW isometric view of a second embodiment of a bracket;

Figure 11 is a front elevation of the bracket of the second embodiment; Figure 12 is a front elevation of a conventional back-box showing the securing holes;

Figure 13 is a SW enlarged fragmental view showing the front of a wall in the first step in the use of the second embodiment;

Figure 14 is a SW enlarged fragmental view showing the front of a wall in the a second step in the use of the second embodiment;

Figure 15 is a NW enlarged fragmental view showing the back of a wall in the third step in the use of the second embodiment;

Figure 16 is a SW enlarged fragmental view showing the back of a wall in the third step in the use of the second embodiment;

Figure 17 is a SW enlarged fragmental view of the fourth and final step in the use of the second embodiment;

[0020] Figure 18 is a flow chart showing the steps in the use of the second embodiment;

Figure 19 is a SE isometric view of a back-box of a third embodiment; and Figure 20 is a SW isometric view of a fourth embodiment of a back-box.

Detailed Description

First embodiment

[0021] Figures 5-9 illustrate a bracket 8 for securing a conventional two gang back-box 7. The bracket 8 is fabricated to have an elongate back limb 9 and two opposed similar side limbs 10 depending from the ends of the back limb 9. Each end of the side limbs 10 join with a fixing part provided by a fixing panel 11 .

[0022] The bracket 8 is formed from a single pressed elongate flat metal panel. The back limb 9 is formed from a median part of the elongate rectangular planar panel. Stiffening elements 12 are formed by rolling the long straight edges of the median part. Each side limb 9 is formed by bending each elongate portion of the member adjacent the median portion into an S shape extending generally perpendicular to the plane of the member. The “S” shape facilitates resilient deformation of the side limb 10. The second bend of each “S” shaped side limb is flattened to present an extended gripping surface 13 . The gripping surface may be modified by the provision of surface features such as teeth, spikes or knurling to enhance the grip on the sides of the back-box.

[0023] The fixing panel 11 is formed by bending the extreme ends of the member so that they are parallel to the back limb 9 and extend out from the back limb when the bracket grips a back-box. In the relaxed condition the distance between the opposing gripping surfaces 13 is designed to be less than the width “W” of a standard metal back-box, that is to say less than 140mm in the case of a double gang box ( 70mm in the case of a single gang back-box) so that the side limbs need to be bent resiliently in order to receive the back-box. In the relaxed condition each fixing panel 11 will be inclined with respect to the back panel so that the panels 11 take up a parallel condition when gripping the back-box. Each side limb 10 is bent so that when applied to a back-box of matching size a portion of the back-box projects in front of the panel 11 less than or equal to the thickness of the wall board. Wall board comes in standard thicknesses of 15, 12 or 9mm so that if the projection “P” is set to be 9mm the bracket will nevertheless work in a thicker 15 or 12mm wall board, the object being that the front edge of the back-box should not project from the front surface of the wall board, but is flush or recessed.

[0024] The method of fitting the back-box using the bracket is shown in figure 4 and comprises the steps of S1 going to the front side of the wall. Step 2 cut the hole 5 for the back-box 7. Step S3 go to the back side of the wall. Step S4.1 bend the ends of the bracket apart so that the back-box can be slid between the gripping surfaces 13, then release the ends to grip the back-box. Step S5.1 apply the back-box 7 to the hole 5 so that the flat panels 11 bear against the back of the wall board 4. At step 6.1 the bracket 8 and back-box 7 is secured to the back of the wall board by means of drywall screws 15 driven through the holes 14.

[0025], Metric drywall screws have standard dimensions in accordance with Table 1 below:

Second embodiment

[0026], The second embodiment of the bracket is shown in figures 10-18 has a back limb 9 generally similar to the first embodiment. Holes 9.1 are arranged to perforate the back limb in a pattern corresponding to the hole slots 22 commonly provided in the rear panel of a metal back-box. The holes 9.1 are formed to threadedly engage a self-tapping screw

SUBSTITUTE SHEET (RULE 26) such as an M3.5 drywall screw. The side limbs 10 diverge at right angles from the back limb and are straight instead of “S” shaped. The length of each side limb 10 is determined to be compatible with a specified depth of back-box, approximately 38 mm for a 47mm deep back-box, 25 mm for a 35mm back-box or 16 for a 25mm deep back-box. It will be evident to the skilled person that these dimensions will differ for back boxes of different dimensions. The distal end of each side limb remote from the back limb is bent out away from the back limb and at right angles to the side limb to form a fixing member 11. A gusset 10.1 is formed bent out from each side of each limb 10 to engage the fixing member 11 and reinforce the bracket.

[0027] Each fixing member 11 is adapted by means of a large array of tap holes 23 each compatible with a standard self-tapping screw such as an M3.5mm dry wall screw. The periphery of each hole 23 of the array of tap holes (23) is separated by less than the radius of the tap hole from each adjacent tap hole, preferably the separation is less than half the radius. The height of the fixing member 11 is less than the height of the hole5, ie less than 70mm.

[0028] The bracket of the second embodiment may be resiliently deformable to grip the sides of a back-box as described in the use of the first embodiment, however the second embodiment can be used in a process illustrated in figures 13 to 18. In this process the back-box and bracket are installed entirely without accessing the rear surface of the wall board. In the first step S1 the tradesman access the front side of the stud wall 4 and cuts a rectangular hole 5 corresponding in size to the back-box to be fitted, ie 140mm X 70mm or 70mm X 70mm. The correspondingly sized bracket 8 is selected and fed through the hole 5 as shown in figure 14 and step 4.2 and worked around until each fixing member is sited equidistant from the sides of the hole and pressed against the back surface of the wall board 4. In this condition the tradesman drives a self-tapping drywall screw through the front face of the wall adjacent each side of the hole, step S4.3. The provision of a large number of closely spaced tap holes in the fixing part ensures that the drywall screws can engage with and screw into one of the tap holes 23, even if, as is probable, the screws are not exactly aligned with any one of the tap holes.

[0029] Once the bracket is secured in place as shown in figures 15 and 16 the back-box 7 is inserted into the hole 5 as shown in figure 17 and secured to the bracket by driving a further self-tapping screw through one of the slots 22 ad into one of the tap holes 9.1 .

[0030] In a variant of the second embodiment (not shown) the fastening members may be formed by slitting and expanding the end regions of the metal panel from which the bracket is formed to provide an expanded metal mesh fastening member. The mesh is fabricated by expansion to form holes of less diameter than the commonly used dry wall screws (3.5mm) ie the pitch of the mesh is more than the minor diameter and less than the major diameter of a metric standard drywall screw so that self-tapping screws of appropriate size can be screwed into the fastening members. In a further variant of the second embodiment the entire bracket may be formed from expanded metal mesh. This obviates the requirement for formation of the holes 9.1 or 23 by drilling or stamping. The mesh is formed from a gauge of sheet metal selected to provide the required stiffness and expanded to form holes sized to receive and engage self-tapping screws such as dry wall screws, in order to be secured to the back of the wall board as described and for a back box to be secured to the bracket. Third embodiment

[0031] Figure 19 shows a third embodiment for the fourth aspect of the invention in which a back-box 7 is formed to have fixing parts provided by flat panels 11 extending out from side walls 15 16 and top and bottom walls 17, 18. The method associated with the back-box of this embodiment is similar to the method of figure 4 but obviates the step 4.1.

Fourth embodiment

[0032] Figure 20 shows a fourth embodiment for the fourth aspects of the invention in which the metal back-box 7 is generally similar to a conventional back-box but has parallel cuts 19 formed from the leading edge of the side and top and bottom walls to extend part of the depth of the back-box corresponding to the projection distance P. The method associated with this back-box replaces the step 4.1 with bending the tabs 20 formed between the cuts 19 at right angles out from the respective wall to form a mounting bracket to bear against the back of the wallboard. Each tab is formed with a screw hole 21 allowing a securing screw to be driven through the tab to secure the back-box to the back of the wall board.

Claims

A back-box mounting bracket comprising: a back limb (9); opposing side limbs (10) extending one each from each proximal end of said back limb

(9); each side limb extending to support a fixing part (11), each fixing part (11) extending one from each distal end of each side limb, wherein each said fixing part (11) extends to bear against the back surface of a wall board to be threadedly engaged by a self-tapping screw driven through the wall board; characterised in that each fixing part (11) is adapted by; the provision of an array of tap holes (23) spaced by less than the half the radius of each tap hole, or by fabrication of the fixing part (11) from a metal mesh, wherein the pitch of the mesh is more than the minor diameter and less than the major diameter of a metric standard drywall screw, to receive and threadedly engage the at least one self-tapping screw.

A back-box mounting bracket according to claim 1 wherein tap holes (23) are provided in the back limb (9) to threadedly receive one or more self-tapping screws. A back-box according to claim 2 wherein said tap holes (23) are disposed in a pattern corresponding to a pattern of through screw through holes (9.1) formed in a rear panel of a conventional back-box.

A back-box mounting bracket according to any one of the preceding claims wherein the metal mesh is an expanded metal mesh with a shortway pitch greater than the minor diameter of a compatible drywall screw.

A back-box mounting bracket according to any one of the preceding claims wherein the fixing part (11) is a substantially flat panel having a height and length, wherein the height is less than the height of a standard sized back-box.

A back-box mounting bracket according to any one of the preceding claims wherein each of the back limb (9) and each side limb (10) have a height of less than the height of the back-box.

A back-box mounting bracket according to any one of the preceding claims wherein each side limb (10) is formed with a gripping part separated by less then the width of a standard back-box, whereby the side limbs (10) can be resiliently spread apart to receive the opposing side walls of a back-box, so that when the side limbs (10) relax they grip the back-box. 17

A back-box mounting bracket according to claim 7 wherein each gripping part is treated to enhance the gripping effect.

A back-box mounting bracket according to claim 8 wherein the treatment is the provision of knurling, spikes or ridges.

A back-box mounting bracket according to any of claims 7-9 having an “S” shape to facilitate resilient deformation.

A method of mounting a back-box in a stud wall using a bracket according to any one of claims 1 to 6 comprising the steps of: selecting a back-box of appropriate size; selecting a mounting bracket of size compatible with the back-box; cutting a hole corresponding to the height and width of the selected back-box through the wallboard of the stud wall; manually inserting the mounting bracket into the hole so that each fixing part (11) bears against the inside surface of the wallboard one adjacent each side of the hole; driving a drywall screw through the front face of the wall board adjacent the side of the hole and into the fixing part (11); inserting the back-box into the hole; driving a drywall screw through a through hole in the rear panel of the back-box, to thread into a tap hole in the back limb (9). 18

A method of mounting a back-box in a stud wall having only one wallboard panel whereby the wallboard is accessible from the rear using a bracket according to any one of claims 7 to 10 comprising the steps of: selecting a back-box of appropriate size; selecting a mounting bracket of size compatible with the back-box; cutting a hole corresponding to the height and width of the selected back-box through the wallboard of the stud wall; expanding the side limbs (10) of the bracket and inserting a back-box so that the back-box is gripped by the gripping parts; inserting the front edge of the back-box into the hole so that the fixing parts bear against the back face of the wall board; driving drywall screws through he fixing parts into the wallboard to secure the bracket and back-box.