AU745114B2

AU745114B2 - Construction technique

Info

Publication number: AU745114B2
Application number: AU71861/98A
Authority: AU
Inventors: David Robert Collins; Greg Wicks
Original assignee: James Hardie Research Pty Ltd
Current assignee: James Hardie Technology Ltd
Priority date: 1997-06-13
Filing date: 1998-06-12
Publication date: 2002-03-14
Anticipated expiration: 2018-06-12
Also published as: AU7186198A

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION a a.

a a. *0t** FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address of Service: Invention Title: James Hardie Research Pty Limited Greg Wicks and David Robert Collins BALDWIN SHELSTON WATERS MARGARET STREET SYDNEY NSW 2000 CONSTRUCTION TECHNIQUE Details of Associated Provisional Application No. P07347 dated 13 June, 1997 The following statement is a full description of this invention, including the best method of performing it known to me/us:- -2- The present invention relates generally to building construction techniques.

The invention has been developed primarily for use in relation to housing construction and will be described hereinafter with reference to this application. It will be appreciated, however, that the invention is not limited to this particular field of use.

In conventional modem housing construction, walls are generally fabricated by first erecting a structural frame, which is typically formed from timber or steel. The frame is lined internally with a suitable lining material such as plasterboard or fibre cement sheeting, which is finished to conceal joins and finally painted. The external wall is traditionally formed from brick veneer or masonry which provides the advantages of strength, durability and resistance to adverse weather conditions in a relatively cost effective manner. A particular advantage of masonry construction is the look and feel of S"solidity, which many home owners in the current market find desirable.

In the past, alternative external cladding materials have also been used. These include timber weatherboards, roll formed aluminium panels, and fibre reinforced cement sheeting, planks and boards in various surface textures and finishes. These materials are .0 competitive with brick veneer construction on a cost basis. However, a major disadvantage is that such cladding materials do not exhibit the same strength, impact resistance, and feel of solidity as masonry. In particular, they tend to produce a hollow "drumming" sound when knocked. This tends to convey a subjective perception of insubstantiality or flimsiness, notwithstanding the fact that the construction may well possess adequate structural integrity in objective terms.

In an attempt to overcome this problem, it is known to construct wall sections by first forming a structural frame, erecting formwork around the frame, and filling the cavities around the frame members with mortar or concrete. The formwork is removed when the -3concrete has set sufficiently to be self-supporting, thereby providing a free-standing structural wall formed substantially of concrete. The need for internal steel reinforcing may be obviated by the use of fibre reinforced cement cladding. In a variation on this method, permanent formwork can be made from fibre reinforced cement sheets. Whilst these techniques provide the desired feel of solidity and substantiality, they possess inherent disadvantages. The most significant problem is that because of the quantity of concrete required to fill the wall cavities and the relatively high labour content involved in erecting the formwork, the technique is not cost effective in comparison with conventional masonry construction. Furthermore, because concrete typically exhibits relatively poor thermal insulation properties, it is not suitable for domestic dwellings without the addition ti:'of an internal or external layer of insulation, which adds further to the cost of construction S"in terms of both labour and materials.

It is an object of the present invention to overcome or substantially ameliorate at least some of these disadvantages of the prior art.

Accordingly, in a first aspect, the invention provides a method of building construction, including the steps of erecting a structural frame from spaced apart frame members, applying an external layer of cladding material to an outer side of the frame to define an open cavity bounded by the external cladding material and the frame members, and applying a relatively thin layer of cementitious material to an inner surface of the external cladding material so as to extend only partially into the cavity.

Preferably, the method includes the further step of applying an internal layer of lining material to an inner side of the frame, thereby substantially closing the cavity.

According to a second aspect, the invention provides a building section including a structural frame formed from spaced apart frame members, an external layer of cladding ,l-tl -4material applied to an outer side of the frame to define an open cavity bounded by the external cladding material and the frame members, and a relatively thin layer of cementitious material applied to an inner surface of the external cladding material so as to extend only partially into the cavity.

Preferably, the building section further includes an internal layer of lining material applied to an inner side of the frame, to substantially close the cavity.

The invention flows from the unexpected realisation that the provision of a layer of cementitious material significantly thinner than a typical wall cavity, when applied to the ~internal surface of an external layer of cladding material, substantially avoids "drumming" and thereby provides externally the feel of a solid wall, without the need to fill the entire *wall cavity.

S"In the preferred embodiment, the method is applied in the formation of external walls in domestic housing construction. The frame members preferably comprise spaced apart vertically extending steel studs with suitable horizontal or inclined connecting members such as top plates, bottom plates and noggins. Alternatively, however, conventional timber o framing members or other suitable materials may be used.

In the preferred embodiment, the external layer of cladding material comprises fibre reinforced cement sheets. The external fibre reinforced cement sheets are preferably between 4 mm and 15 mm, and ideally around 7.5 mm, in nominal thickness.

Alternatively, however, partially overlapping planks, boards or panels could be used for the external cladding. Cement bonded particle board, in the form of sheets or planks, may also be employed for this purpose.

Preferably, the cementitious material takes the form of a concrete formulation, which is sufficiently fluid for application by spraying, and sufficiently sticky and stiff to remain ~T1T~-L- "i I r- r r--..i.lr ;;ll lr; substantially in place once applied. It should be appreciated, however, that any suitable mixture of cement, sand, water and other additives may be used. Moreover, the definition of "cementitious" is not limited to mixtures containing cement, but should also be understood to include other materials with similar binding properties such as adhesive clays, resin bound sands, resin based concretes, magnesium phosphate cements, plasters, mortars, and other such materials. The principal requirements are simply that the material should be sufficiently formable to facilitate initial application, sufficiently adherent to bind to the vertically oriented cladding material without slumping, and subsequently settable in situ.

10 It should further be understood that the cementitious material need not be applied by *0 spraying, but may also be applied by trowel or other means. Additionally, the cementitious S o layer could be manufactured off-site, for example as fibre reinforced cement sheets, and subsequently secured as panels to the cladding material by screw fasteners, adhesives, or o..

other suitable fastening means.

The cementitious layer is preferably between 10 mm and 70 mm thick. The layer is ideally around 25 mm in thickness for normal density concrete (around 2500 kg/m3), and mm in thickness in the case of light weight concrete (around 1000 kg/m 3 The internal lining material is preferably formed from plasterboard or fibre reinforced cement. Again, however, other suitable materials may also be used.

In one embodiment, a layer of textured coating such as an acrylic, cementitious or epoxy based formulation, is applied to the outer surface of the external cladding material, and finished with a desired surface texture prior to painting. This technique gives the external appearance of cement rendered masonry construction at a competitive cost. A -Y I: surface coating also facilitates concealed joining of fibre reinforced cement sheets with woven reinforcing tape, or a flexible jointing compound.

In one preferred embodiment, the residual void region of each wall cavity not occupied by the internal layer of concrete, is filled or partially filled with a suitable insulation material such as fibreglass batts, fibrous plastic batts, expanded polystyrene foam, or the like. The void region preferably also accommodates electrical wiring, water pipes, communication lines, or other building services.

~A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:to Figure 1 is a perspective view showing a wall section manufactured in accordance with the present invention, prior to application of the internal lining; Figure 2 is a plan view showing the wall section of Figure 1, with the lining material in place; and Figure 3 shows a vertical cross section through a single storey wall section, incorporating a window cavity, manufactured according to an alternative embodiment of .i the invention.

Referring initially to Figures 1 and 2, the invention provides a method of building construction which is particularly well adapted to forming external structural walls 1 in domestic dwellings. Initially, a structural frame is erected on a suitably prepared foundation using spaced apart frame members 2. Preferably, the frame members comprise vertically extending generally U-shaped steel framing studs, which are typically either 76 or 92 mm in width, and spaced apart at 450 imn or 600 mm intervals. It should be appreciated, however, that conventional timber stud framing is an equally preferred method, and that other framing techniques could also be used.

rz -I;-i-ii 1 1 1 li-r~r~ i; -7- With the frame erected, an external layer of cladding material in the form of fibre reinforced cement sheets 5 are applied to the outer surface of the frame. The external fibre reinforced cement sheets are preferably between 4 mm and 15 mm, and ideally around mm, in nominal thickness. It has been found that sheets of this dimension represent a reasonable balance between strength, solidity, weight and cost. The fibre reinforced cement sheets are attached by means of self-drilling, self-tapping screw fasteners 6 (see Figure 2) which extend into the adjacent flanges of the studs. Alternatively, however, other fastening means may be used. In the case of timber framing, nails are the preferred fastening means. The fibre reinforced cement cladding sheets 5 and the framing studs 3 together define an open wall cavity 8, approximately 75 to 100 mm in depth, as defined by e the width of the framing studs.

"The next step in the process involves applying, preferably by spraying, a relatively thin layer 10 of concrete or other suitable cementitious material over substantially the entire internal surface of the fibre reinforced cement cladding sheets, where a solid feel is 15 required. For example, this may not be necessary on a second storey where an external feel •of solidity is not required. The concrete layer is preferably between 10 mm and 50 mm, and ideally around 25 mm in depth for normal density concrete. The concrete material comprises a suitable mixture of sand, cement and water, together with suitable additives adapted to facilitate adherence or sticking of the sprayed concrete to the inner surface of the fibre reinforced cement sheets. Various concrete formulations suitable for this purpose are well known to those skilled in the art, and so will not be described further.

Optionally, additional screw fasteners 6A may be installed into the cladding sheets so as to extend into the wall cavity 8, intermediate the studs. These can conveniently act as depth markers to facilitate a reasonably uniform application of concrete. Optionally also, a -8support mesh may be applied across the external faces of the framing prior to the application of the external cladding to facilitate adherence of the cementitious material.

It will be appreciated that by the method described, the concrete layer 10 extends only partially into the open wall cavity 8, leaving a residual space or void region 12.

Typically, the depth of this residual void region will be around 40 to 50 mm (assuming 76 mm wide studs) and is preferably greater than around 30%, and ideally greater than around of the depth of the overall cavity. The void may be filled with a suitable insulation material such as fibreglass batts, rock wool, expanded polystyrene foam, or the like. It may also be used to accommodate concealed electrical wiring, plumbing, communication 10 lines, air ducting, or other services. Both the insulation materials and the service lines may o..

be conveniently installed at this stage, if required.

Finally, an internal lining material 15 is fastened to the inner side of the frame, by o• attachment to the adjacent flanges of the framing studs 3. Again, self tapping screw fasteners may conveniently be used for this purpose. A suitable lining material is fibre 15 cement sheeting or plasterboard which is usually taped, set, then sanded to conceal join lines in conventional manner, and finally painted. Other alternatives such as timber panelling may also be used. It should be appreciated, however, that in some applications such as garages where aesthetics are less significant, the internal lining may be omitted to minimise cost.

If desired, a layer of textured surface finish (not shown), such as an acrylic, cementitious or epoxy based formulation, may be applied to the outer surface of the external cladding. This technique gives the external appearance of cement rendered brick or block work veneer construction.

1; Figure 3 shows a vertical cross section through a single storey wall 19 of a domestic dwelling, manufactured in accordance with an alternative embodiment of the invention, using timber framing studs. In this case, it will be seen that the vertical timber frame members 2 are braced by horizontally extending top plates 20, bottom plates 21 and noggins 22. The bottom plates are fixed to a concrete foundation slab or footing by means of"dynabolts" 23 or other suitable fastening means. It will be seen that the wall section also incorporates an insulation layer 25 and an external cladding layer 26, formed from fibre reinforced cement sheets. A coating system 27 is applied to the sheets. In this case, an aluminium window frame 30 has been included for illustrative purposes.

Additionally, it will be noted that a series of horizontally extending timber battens 32 extend across the framing studs. Each batten is preferably around 35 mm by 35 mm in cross section and the battens are vertically spaced apart at approximately 400 mm centres.

It will be appreciated, however, that the battens may be formed of different materials, such as metal. They may also be spaced and oriented differently, as required. By extending across the external side of the stud framing, the battens provide supports onto which the *.i external facing sheets are fastened. After the cladding sheets are fastened into place, the cementitious mortar 10 is applied behind the inside of the cladding sheets, as previously described. The cement mortar may cover the battens if desired.

The principal advantage conferred by this method of construction is to conceal irregularities in the stud framing, such as may occur when major framing elements differ in depth, or are twisted or warped. It has been found that the additional cost of using the battens is largely offset by the reduced costs in making good the uneven sheet joints which typically arise due to framing irregularities.

3 ~1 i: ~i~i-iil-1I I1I--( C; It has been found, unexpectedly, that a layer of cementitious material significantly thinner than a conventional wall cavity, when applied to the internal surface of an external cladding material such as fibre reinforced cement, substantially avoids the "drumming" phenomenon when knocked and otherwise provides externally the look and feel of a solid wall, without the need to fill the entire wall cavity. Advantageously, this substantially reduces the amount of concrete material required, and at the same time facilitates the concealed routing of building services. The technique also facilitates the provision of an .0000: insulation layer, in the residual void region defined between the concrete layer and the internal lining. The result is a commercially viable alternative to masonry construction which avoids many of the problems associated with previously known cladding techniques including lack of strength and impact resistance. Moreover, the fact that the relatively heavy concrete layer can be applied in situ, after the cladding sheets have been erected, substantially facilitates transportation, handling and installation of the framing and cladding. In each of these and other respects, the invention represents a commercially significant improvement over the prior art.

Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

1. A method of building construction, including the steps of erecting a structural frame from spaced apart frame members, applying an external layer of cladding material to an outer side of the frame to define an open cavity bounded by the external cladding material and the frame members, and applying a relatively thin layer of cementitious material to an inner surface of the external cladding material so as to extend only partially into the cavity.

2. A method according to claim 1, including the further step of applying an internal layer of lining material to an inner side of the frame, thereby substantially closing the 10 cavity.

3. A method according to claim 1 or claim 2, wherein the frame members include spaced apart generally vertically extending studs.

A method according to claim 3, wherein the studs are formed substantially from .o steel. 15

5. A method according to claim 4 wherein the frame members comprise vertically extending generally U-shaped steel framing studs and the external layer of cladding material is secured to one arm of said U-shaped stud.

6. A method according to claim 3, wherein the studs are formed substantially from timber.

7. A method according to any one of claims 3 to 6, wherein the studs are joined by generally horizontal or inclined connecting members.

8. A method according to claim 7, wherein the connecting members include top plates, bottom plates or noggins. -12-

9. A method according to any one of the preceding claims, wherein the external layer of cladding material includes fibre reinforced cement sheets.

A method according to claim 9, wherein the fibre reinforced cement sheets are between 4 mm and around 15 mm in nominal thickness.

11. A method according to claim 10, wherein the external fibre reinforced cement sheets are around 7.5 mm in nominal thickness.

12. A method according to any one of claims 1 to 8, wherein the external layer of cladding material is formed from partially overlapping planks, boards or panels.

13. A method according to any one of claims 1 to 7, wherein the external layer of 10 cladding material is formed from cement bonded particle board. o:o

14. A method according to any one of the preceding claims, wherein the cementitious material takes the form of a concrete formulation.

°15. A method according to claim 14, wherein the concrete formulation is sufficiently ooo. i fluid for application by spraying and sufficiently sticky and stiff to remain substantially 15 in place once applied.

16. A method according to any one of claims 1 to 13, wherein the cementitious material is selected from a group of cementitious materials including adhesive clays, resin bound sands, resin based concretes, magnesium phosphate cements, plasters, and mortars.

17. A method according to any one of the preceding claims, wherein the cementitious material is applied by spraying.

18. A method according to any one of claims 1 to 16, wherein the cementitious material is applied by trowel. -13-

19. A method according to any one of claims 1 to 16, wherein the layer of cementitious material is manufactured off-site and subsequently secured in panel form to the cladding material by fastening means.

A method according to any one of the preceding claims, wherein the cementitious layer is preferably between 10 mm and around 70 mm in thickness.

21. A method according to any one of the preceding claims, wherein the cementitious layer is formed from normal density concrete and is around 25 mm in thickness.

22. A method according to any one of claims 1 to 20, wherein the cementitious layer is formed from light weight concrete and is around 50 mm in thickness. 10

23. A method according to any one of claims 14 to 22 when dependent from claim wherein the concrete formulation is applied so as to extend at least partially over said one arm of said U-shaped stud.

24. A method according to any one of claims 2 to 23, wherein the internal lining material is formed from plasterboard.

25. A method according to any one of claims 2 to 23, wherein the internal lining material is formed from fibre reinforced cement sheet.

26. A method according to any one of the preceding claims, including the further step of applying a layer of cement render to an outer surface of the external cladding material.

27. A method according to claim 26, including the further steps of finishing the layer of cement render with a desired surface texture and subsequently painting the cement render to provide an external appearance of cement rendered masonry.

28. A method according to any one of claims 1 to 25, including the further step of applying a layer of an acrylic or an epoxy based formulation to the outer surface of the Aexternal cladding material. -14-

29. A method according to claim 28, including the further steps of finishing the layer of acrylic or epoxy based formulation with a desired surface texture and subsequently painting the layer to provide an external appearance of cement rendered masonry construction.

30. A method according to any one of the preceding claims, wherein the residual void region of each wall cavity not occupied by the internal layer of cementitious material is filled at least partially with an insulation material.

31. A method according to claim 30, wherein the insulating material is selected from a 1 group including fibreglass batts, fibrous plastic batts, and expanded polystyrene foam.

32. A method according to any one of the preceding claims, wherein the residual void region of each wall cavity not occupied by the internal layer of cementitious material accommodates electric wiring, water pipes, communication lines or other building services. i

33. A method according to any one of the preceding claims, wherein the frame 15 members are between 75 mm and around 100 mm in depth.

34. A method according to any one of the preceding claims, including the further step of fixing screw fasteners of uniform length through the external layer of cladding material, to protrude into the open cavity intermediate the frame members, thereby providing depth markers to facilitate uniform application of the layer of cementitious material.

A method according to any one of the preceding claims, wherein a residual void region of the cavity, not occupied by the layer of cementitious material, has an average depth greater than around 50% of the average depth of the cavity overall.

36. A method according to any one of the preceding claims, including the further step of providing battens across the frame members to provide support for the external layer of cladding material.

37. A method according to claim 36, wherein at least some of the battens are disposed in a generally horizontal orientation.

38. A method according to any one of the preceding claims, including the further step of applying support mesh between the outer faces of the frame members and/or across inner surfaces of the cladding material, to facilitate adherence of the cementitious material. S. a 10

39. A method of housing construction, including the step of forming at least one external wall in accordance with the method defined in any one of the preceding claims.

A building section including a structural frame formed from spaced apart frame members, an external layer of cladding material applied to an outer side of the frame to define an open cavity bounded by the extemal cladding material and the frame members, 15 and a relatively thin layer of cementitious material applied to an inner surface of the external cladding material so as to extend only partially into the cavity.

41. A building section according to claim 40, further including an internal layer of lining material applied to an inner side of the frame, to substantially close the cavity.

42. A building section according to claim 40 or claim 41, manufactured in accordance with the method defined in any one of claims 1 to 39.

43. A domestic dwelling having at least one external wall formed in accordance with the method defined in any one of claims 1 to 39, or having a wall section as defined in any one of claims 40 to 42. i- i I :e' -16-

44. A method of building construction, substantially as hereinbefore described with reference to the accompanying drawings.

A building section substantially as hereinbefore described with reference to the accompanying drawings.

46. A method according to any one of claims 1 to 39 wherein the thin layer of cementitious material is sufficient in combination with said frame and external cladding to substantially eliminate drumming when knocked as herein described and provide a solid feel that approximates that of a solid brick or filled wall.

47. A building section according to any one of claims 40 to 43 wherein the thin layer 10 of cementitious material is sufficient in combination with said frame and external cladding to substantially eliminate drumming when knocked as herein described and provide a solid feel that approximates that of a solid brick or filled wall. DATED this 16 th Day of January, 2002 JAMES HARDIE RESEARCH PTY LIMITED Attorney: CAROLINE M. BOMMER Fellow Institute of Patent and Trade Mark Attorneys of Australia of BALDWIN SHELSTON WATERS o ~-l