AU666946B2

AU666946B2 - Improvements in finishing plasterboard

Info

Publication number: AU666946B2
Application number: AU41215/93A
Authority: AU
Inventors: Vincenzo Pacetta
Original assignee: ROCCO FALCOMATA
Current assignee: Falcomata Rocco
Priority date: 1992-07-08
Filing date: 1993-06-11
Publication date: 1996-02-29
Anticipated expiration: 2013-06-11
Also published as: AU4121593A

Description

1 666946 1

AUSTRALIA

Patents Act 1990 VINCENZO PACETTA and ROCCO FALCOMATA

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT *6 i *e p

S

p Invention Title: IMPROVEMENTS IN FINISHING PLASTERBOARD The following statement is a full description of this invention including the best method of performing it known to us:- I f The present invention relates to the forming of corner shapes in plasterboard and more particularly to a method of forming a plasterboard sheet and a method of adapting a plasterboard sheet to form a corner with minimal steps to provide an improved shape and finish to that corner.

When plasterers or wall finishers are forming corners with plasterboard, one brand of which is Gyprock (Reg. a pair of plasterboard sheets are edge either side of the corner with the gap between the sheets of the apex of the corner being covered by a metal edging strip. In the case of corners formed in overhead bulkheads a V-notch is formed from the rear surface of the board through to the inner surface of the cardboard sheet S 15 which is to form the outer edge of the corner. After removing that V section of the board which comprises a strip of cardboard from the inner face and a V-notch of sandwiched plaster, the plasterboard sheet can be bent to form the corner by bending the sheet either side of the 20 V-notch to close that notch. The "cornered" sheet of plasterboard can then be affixed to a frame or similar to form a corner. The final finishing process for the corner is the placement of an edging strip along the corner.

This strip is fixed to either side of the corner by fixing 25 expanded metal flanges to the outer face of the plasterboard on opposite sides of the corner and thereafter finishing coats of plaster are built up against the edging strip and feathered back into the plane of the plasterboard far enough away from the corner so as to give the appearance of a continuum of the plasterboard from the commencement of the feather zone to the apex of the edging strip. Similar considerations apply when forming an external vertical corner along a wall surface where plasterboard sheets are butted at the corner.

It will be appreciated that this previous process 3 alters the external angle of the corner due to the build up of the finishing strip and plaster on the exterior side of the corner. To explain, most corner edges are at 900 and it will be appreciated that the existing technique does not form a true 900 corner but is at an angle somewhat less than that due to the projection of the edging strip at the corner and a gradual build up of plaster from the plane of the plasterboard to the apex of the edging strip. The lack of a true 900 corner can cause some difficulties with accurate fitment of skirting boards and cornices. If it was possible to accurately and easily form a 900 corner, then the eye appeal will be improved as well as facilitating the accurate fitment of skirtings and cornices about a corner.

The present invention proposes a method for forming corners, whether of U, L or V shape, in plasterboard sheeting which enables a ready and accurate finishing off process having benefits over the known techniques.

In an effort to ameliorate the disadvantages of the prior art it is proposed to provide a method of forming a corner in a plasterboard sheet which offers a choice over the prior art methods and, at least in the preferred embodiments, allows a corner to be formed at the true angle with minimal finishing required.

25 Accordingly, in a first aspect the present invention provides a method of forming a corner in a plasterboard sheet comprising two cover sheets with plaster sandwiched therebetween, said method comprising the steps of: forming an elongate recess portion in a face of said plasterboard sheet, forming an elongate notch substantially aligned with said recess portion on an opposite face of said plasterboard sheet, and bending the plasterboard sheet about the notch to close said notch.

4 By providing a recess portion on that side of the plasterboard sheet which forms the exterior side of the corner, the apex of the corner may be finished while still retaining its true angle.

To explain, when the plasterboard is closed about the notch, the elongate recess portion will extend along either side of the apex of the corner. The plasterboard sheet extending on either side of the corner may then be finished without the finishing coats of plaster extending past the plane of the plasterboard.

In one embodiment, the recess portion forming the exterior of the corner is preferably covered with an elongate finishing strip. This elongate finishing strip may then be attached to the plasterboard sheet by appropriate application of plaster. The recess portion on either side of the apex of the corner receives the elongate finishing strip and layers of plaster such that they do not extend past the plane of the plasterboard.

Accordingly, by using the present inventive method, a 20 corner may be formed in a plasterboard sheet such that the corner is at its true angle. Such true angle not only improves the aesthetics of the corner but also facilitates accurate fitment of skirting boards, cornices etc. about the corner.

S 25 In another embodiment of the present invention, the recess portion on the plasterboard sheet comprises an inner or central deeper recess portion with two outer or boundary shallower recess portions along either side thereof. This type of recess portion may be matched with a finishing strip comprising an elongate metal strip with paper or paper-like webs extending from either side thereof. When such a finishing strip is applied to the apex of the corner, the metal strip is preferably positioned in the inner deeper recess portion with the paper or paper-like web extending into the outer shallower 5 recess portions on either side thereof. These paper or paper-like webs assist attachment of the metal finishing strip to the apex of the corner. Once the edging strip is in place, the finishing off of the corner can be easily achieved by the addition of filler compound between the apex of the corner, which is now formed by the outer edge of the paper covering the elongate finishing strip, and the planar surface of the unrecessed portions of the plasterboard on either side of the corner.

To ensure the recess portions on either side of the corner apex are symmetrical, it is preferred that the notch about which the plasterboard is bent is substantially centrally aligned with the recess portion.

It is also preferred that the elongate notch extends from S 15 one face of the plasterboard sheet to a position directly adjacent the underside of the recess portion.

The recess portion may be formed by any appropriate method. Embossing of the plasterboard sheet by, for example, a roller means is a particularly preferred method 20 of forming the recess portion. Such embossing may occur before, during or after curing of the plasterboard sheet.

S..It is also possible to form the recess portion either before or after the forming of the elongate notch and in fact the recess portion may be formed after the 25 plasterboard sheet is bent to close the notch.

By appropriate dimensioning of the depth of the recess portion and the angle and thickness of the edging strip, it is possible to accurately form corners of any desired angle by application of the present invention.

In another aspect, the present invention also provides a method of adapting a plasterboard sheet to form a corner comprising the steps of forming an elongate recess portion in a face of said plasterboard sheet and forming an elongate notch substantially aligned with said recess portion on an opposite face of said plasterboard 6 sheet.

By providing such a plasterboard sheet, the builder may simply form a corner by bending the inventive plasterboard sheet about the elongate notch to close the notch.

The formation of the recessed portion may, as described above, be formed before during or after formation of the plasterboard sheet. If the formation of the recessed portion is carried out prior to curing of the plasterboard, the plasterboard when dry will avoid the problem of separation between the plaster inner and outer card or paper sheet and crumbling of adjacent plaster that can more readily occur when the recess portion is formed after the plasterboard has fully cured.

If a recess portion is formed at predetermined spaced apart zones during the wet forming stage of the plasterboard, the resultant board will have its normal planar surface on one side and a series of parallel spaced apart recessed portions on the other. Such a sheet will 20 be equally suited for providing a smooth finished wall or ceiling with the unrecessed face outermost, while having the dual advantage of being able to be formed into corners by slicing off a section with a recessed portion, forming the corner and fitting it about a corner frame.

25 As discussed above, the recess portion may comprise an inner or central deeper recess portion with two outer boundary or shallower recess portions on either side thereof and may be formed before or after formation of the notch or bending of the plasterboard sheet to close the notch to form a corner. It is also envisaged that the outer or boundary shallower recess portions may be formed while the sheet is dry and flat, the notch then formed on the plasterboard sheet, the plasterboard sheet bent to form the corner and the inner or central deeper recess portion subsequently formed after the corner shape has been set.

In a third aspect, the present invention provides a plasterboard sheet adapted to form a corner, said sheet comprising two cover sheets sandwiching plaster therebetween, an elongate recess portion on one face and an elongate notch substantially aligned with said recess portion on an opposite face such that said plaster sheet may be bent about said notch to close said notch and form a corner.

In a fourth aspect, the present invention comprises an assembly for forming a corner comprising the abovementioned inventive plasterboard sheet and a finishing strip, said finishing strip being matched to fit within and cover said recess portion after said plaster 15 sheet is bent about said notch to form a corner.

In order that the nature of the present invention may be more clearly understood, preferred embodiments of the invention will now be de~ ribed by way of example only with reference to the accompanying drawings in which: 20 Figs 1A-1D are sectional views of a sheet of plasterboard showing the steps of a first embodiment of :the method of the invention in forming an external right angled corner; Figs 2A-2D are sectional view of a sheet of 25 plasterboard showing the steps of a second embodiment for forming an external right angled corner; Figs 3A-D are sectional views of a sheet of plasterboard showing the steps of a third embodiment for forming a "Z--shaped corner with the external corner being formed using the embodiment of Fig 2; and Figs 4A and 4B are sectional views showing the conventional technique for forming a "Z"-shaped corner.

Figs 1A-ID depict a first embodiment in accordance with the invention for forming an external right angled corner in a plasterboard sheet. With appropriate variations or modifications, the inventive method may be 8 readily adapted to formation of any angled external corner as will be readily understood.

Fig 1A shows a sheet of plasterboard 10 comprising cardboard sheets 12 and 13 with a core of gypsum plaster material sandwiched therebetween.

In this embodiment sheet 13 will form the outer surface or face of the completed corner. Accordingly, recess portion 14 is formed on face sheet 13 of plasterboard sheet 10. This recess portion 14 may be formed either before, during or after curing of the plaster material 11 in plasterboard sheet The next step in the inventive method is shown in S: Fig lB. A V-groove 15 is machined from inner surface or rear sheet 12 through plaster core 11 to a position 15 adjacent face sheet 13. It is preferred that the V- Se groove 15 does not pass through face sheet 13.

The plasterboard sheet shown in Fig lB is now capable of forming a corner simply by bending the plasterboard sheet to close notch 15, as shown in Fig IC.

iii 20 Once notch 15 is closed, it may be finished and secured by paper tape 16 adhered to both sides of the rear sheet 12 of the corner.

As will be clear to a person skilled in the art, once the plasterboard sheet 10 is bent to close notch 25 recess portions 14 will extend along either side of the corner apex. This recess portion allows the apex of the corner to be finished and matched with the remainder of plasterboard sheet 10 extending from either side of the corner without the filler compound extending past the plane of face sheets 13. The inventive method thereby provides the opportunity to form a corner which does not require feathering of the plaster from the corner apex to match the plasterboard sheets extending from either side thereof. In addition, the inventive method provides a corner which, when finished, is not only aesthetically 9 pleasing but is formed at the true and correct external angle.

In another embodiment of the present invention, as shown in Fig IC, the recess portion may include a central or inner deeper recess portion 17 with outer or boundary shallower recess portions 14 extending along either side thereof. Inner recess portion 17 may be formed before or after bending of plasterboard sheet 10 to close notch As shown in Fig ID, it is preferred that the apex of the corner is covered by elongate metal finishing strip 18. This finishing strip preferably has paper or paper-like webs 19 extending from either edge thereof.

Recess portions 17 and 14 are sized in order to receive elongate strip 18 and paper webs 19 respectively. Recess 15 portions 17 and 14 and elongate finishing strip 18 and paper-like webs 19 are dimensioned such that finishing off of the corner by bedding cement and finishing compound O..

will result in a true angled external corner without the excessive build up of finishing plaster which occurs with 20 prior art methods.

9.9.

Recess portions 14 and 17 may be formed by any appropriate method, however embossing of the plasterboard by, for example, a roller means has proved particularly effective in forming these recessed portions.

25 It is not essential to use an elongate metal finishing strip on the apex of the plasterboard corner. A simple paper web may suffice, however the elongate metal finishing strip does provide an accurate and aesthetically pleasing result to the corner apex. In addition, the metal strip acts as a guard to chipping or breakage of the corner.

Another form of metal finishing strip for complementary fitment about the corner apex comprises a plurality of perforations or openings through the strip.

By applying a glue to the strip or corner apex, this glue may flow through the perforations when the strip is applied to the corner apex. This vlue, which has flowed through the strip perforations or openings, may then adhere to an outer or paper-like covering applied to the outer face of the strip. This arrangement provides a more coherent bond between the plasterboard sheet 10, the strip 18 and paper or paper-like web 19.

Turning now to Figures 2A-2D, a second embodiment of the present invention provides a method of forming a corner in a plasterboard sheet 10 wherein recess portion 14 is formed on the face sheet 13. As with the first embodiment, the notch 15 is then machined from rear sheet 12 through to a position adjacent but not perforating face sheet 13 as shown in Fig 2B.

In this embodiment, however, the face sheet 13 in the area of recess portion 14 is pulled back away from the plaster core 11 to form a slot or pocket as shown in Fig 2C. This may be performed before or after formation of V-notch i By detaching the face sheet 13 from the plaster in the area of recess portion 14 a pocket is formed between the face sheet 13 and plaster 11. Two protective finishing metal strips 20 are slid into this pocket as shown in Fig 2C.

As shown in Fig 2D, the plasterboard sheet is then bent to close notch 15. Paper tape 16 preferably covers "i the join on rear sheet 12.

Strips 20 are positioned such that once the plasterboard sheet 10 is bent to close notch 15 and form the corner, the strips 20 extend along either side of the corner apex, This embodiment of the present invention only requires minimal finishing. The apex of the corner is protected by metal strips 20 on either side thereof with the face sheet 13 extending around the entire outer face of the corner. The only finishing off which may be required with this embodiment of the present invention is 11 smoothing of the set mark so left by the formation of recess zone 14. The junction between recess zone 14 and face sheet 13 may be slightly stretched. This set mark may require some finishing.

As shown in Fig 2C to ensure reliable closure of notch 15, glue or some other fixing compound 21 may be applied to the notch 15 prior to closure.

A third embodiment of the present invention is shown in Figs 3A-3D which show a "Z"-shaped corner where the external corner is formed by the technique shown in Figs 2A-2D. The internal corner is produced by a previously known method in which a slot 30 is formed in face 12 to a depth of approximately one third of the thickness of the plasterboard 15 The external corner as shown in Fig 3B is formed in the manner of the embodiment of Figs 2A-2D, whereafter the slot 30 is deepened by running a knife blade on one side e of the slot to create a straight hinge line at the inner 00.0 face of outer cardboard sheet 13 which is then bent to form an internal corner as shown in Fig 3C. The back of the internal corner is then filled with cornice cement 22 and a paper tape 23 applied as shown in Fig 3D, thus resulting in a "Z"-shaped corner which has been easily and quickly formed with minimum finishing as compared with 25 conventional techniques.

This may be compared with the conventional method of forming a "Z"-shaped section in plasterboard shown in Figs 4A and 4B. In this method the formation of V-grooves in the inner and outer faces of the plasterboard requires significant finishing off with the external corner being conventionally finished by applying an edging strip (not shown) as earlier discussed. The internal 12 corner must be filled with compound to cover the gap between separated faces of outer cardboard sheet 13 that arises due to the formation of V-groove It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

6 0* 0 0

Claims

1. A method of forming a corner in a plasterboard sheet comprising two cover sheets of either face with a plaster sandwiched therebetween, said method comprising the steps of; forming an elongate recess portion in a face of said plasterboard sheet, forming an elongate notch substantially aligned with said recess portion on an opposite face of said plasterboard sheet, and bending the plasterboard sheet about the notch to close said notch.

2. A method of forming a corner in a plasterboard sheet as claimed in claim 1 further comprising the step of; S 15 covering said recess portion forming the exterior of the corner with an elongate finishing strip.

3. A method of forming a corner in a plasterboard sheet as claimed in claim 1 further comprising prior to step (c) the steps of; 20 bl) detaching the respective cover sheet from the plaster in the area of the recessed portion and b2) placing two elongate finishing strips between the detached cover sheet and plaster, such that after step (c) said finishing strips are positioned along either side of 25 said corner. C S4. A method of forming a corner in a plasterboard sheet as claimed in claim 1 or 2 wherein said recess portion comprises an inner or central deeper recess portion with two outer or boundary shallower recess portions along either side thereof. A method of forming a corner in a plasterboard sheet as claimed in any one of claims 1, 2 or 4 wherein said finishing strip comprises an elongate metal strip covered with a paper or paper-like web such that said web extends outwardly past the longitudinal edges of said elongate 14 metal strip..

6. A method of forming a corner in a plasterboard sheet as claimed in claim 5 wherein said metal strip is positioned in the inner recess portion with said web extending into the outer recess portions on either side thereof.

7. A method of forming a corner in a plasterboard sheet as claimed in any one of the previous claims wherein, prior to step glue is applied to the notch.

8. A method of forming a corner in a plasterboard sheet as claimed in any one of the previous claims wherein step is performed before or after step or

9. A method of forming a corner in a plasterboard sheet as claimed in any one of the previous claims wherein said S 15 elongate recess portion is formed by embossing before, during or after curing of the plasterboard sheet. A method of forming a corner in a plasterboard sheet as claimed in any one of the previous claims wherein said niotch extends from a face of said plasterboard sheet to a position directly adjacent the underside of said recess portion. 11ii. A method of adapting a plasterboard sheet to form a corner comprising the steps of forming an elongate recess r portion in a face of said plasterboard sheet and forming an elongate notch substantially aligned with said recess portion on an opposite face of said plasterboard sheet.

12. A method of adapting a plasterboard sheet to form a corner as claimed in claim It wherein said recess portion comprises an inner or central deeper recess portion with two outer or boundary shallower recess portions along either side thereof.

13. A method of adapting a plasterboard sheet to form a corner as claimed in claim 11 or 12 wherein said elongate recess portion is formed by embossing before, during or after curing of said plasterboard sheet. 15

14. A method of adapting a plasterboard sheet to form a corner as claimed in any one of claims 11-13 wherein said notch extends from a face of said plasterboard sheet to a position directly adjacent the underside of said recess portion. A plasterboard sheet adapted to form a corner, said sheet comprising front and rear faces sandwiching plaster therebetween, an elongate recess portion on one face and an elongate notch substantially aligned with said recess portion on an opposite face such that said plAster sheet may be bent about said notch to close said notch and form a corner.

16. A plasterboard sheet as claimed in claim. 15 wherein i said recess portion comprises an inner or central deeper recess portion with two outer or boundary shallower recess portions along either side thereof. 444449

17. A plasterboard sheet as claimed in claim 15 or 16 wherein said elongate recess portion is formed by embossing before, during or after curing of said sheet.

18. An assembly for forming a corner comprising a plasterboard sheet according to any one of claims 15-17 and a finishing strip, said finishing strip being matched to fit within and cover said recess portion after said plaster sheet is bent about said notch to form a corner. 25 19. An assembly as claimed in claim 18 wherein said finishing strip comprises an elongate metal strip covered with paper or a paper-like web, said web extending outwardly past the edges of said elongate metal strip such that said metal strip may be positioned within the inner recess portion with said web extending into the outer recess portion on either side thereof. A method of forming a corner in a plasterboard sheet substantially as hereinbefore described with reference to Figures la to 3d of the accompanying drawings.

21. A method of adapting a plasterboard to form a corner -16 substantially as hereinbefore described with reference to Figures la to 3d of the accompanying drawings.

22. A plasterboard sheet for forming a corner substantially as hereinbefore described with reference to Figures la to 3d of the accompanying drawings.

23. An assembly for forming a corner substantially as hereinbefore described with reference to Figures la to -1d of the accompanying drawings. Dated this 11th day of June 1993 VINCENZO PACETTA and ROCCO FALCOMATA BY: P-cLAtcc~ c h V~nce' PaeA+ Ck 0 0# 9*Ccibvoi@++cA 21% *09. ABSTRACT A method of forming a corner in a plasterboard sheet comprising the steps of forming an elongate recess portion (14,17) in a face of the plasterboard sheet, forming an elongate notch (15) aligned with the recess portion (14,17) on an opposite face of the sheet (10) and bending the sheet about the notch to close the notch and form a corner. The recess portion (14,17) is then on the extension of the corner extending along either side of the 15 corner apex allowing the builder to finish the corner without the finishing strips or bedding cement and S: finishing compound extending past the plane of the plasterboard sheet. 6 S *a o