AU2014240183B2 - Rebated Sills and Hobs to Minimise Water Ingress in Poured-in-Situ Concrete Slabs - Google Patents

Abstract

24 ABSTRACT A permanent sill or hob mould for creating a rebated sill or hob on the upper surface of a concrete building slab; said mould comprising side panels maintained in a parallel, fixed spatial relationship by a plurality of 5 transversely-arranged spacer elements; said side panels being shaped to provide a desired cross-sectional shape of said sill or hob, including an outer, lowered rebate and an inner raised part which impedes any tendency for water to flow inwardly into a structure, said rebate being made to accommodate a wall, window or other structure; said sill or hob mould 10 being supported on a plurality of chairs fixed to formwork built for the creation of a concrete building slab during the fixing of steel reinforcing bar, and filled with concrete during the pouring of said concrete slab; means being provided to facilitate filling of said sill or hob mould with concrete. 15 Sheet 2of8 Fg2 z/ 20 le

Description

REBATED SILLS AND HOBS TO MINIMISE WATER INGRESS IN POURED-IN-SITU CONCRETE SLABS

This invention relates generally, as part of the building construction process, to the moulding into cast-in-situ concrete slabs of sills or hobs for the fixing of windows, curtain walls and the like. More particularly, it relates to permanent moulds for the casting of rebated sills or hobs of a form minimising opportunities for the ingress of water.

Particularly in the construction of multi-storey buildings, it is 10 common to provide raised sills or hobs of some form to cast in-situ concrete slabs. Such sills or hobs act as supports for building elements such as window frames, curtain wall panels and the like, providing a watertight barrier beneath such building elements to prevent the ingress of rain water and condensation. Said building elements may incorporate 15 lower frames or sills that bear directly upon and are sealed to a supporting surface such as a cast in-situ concrete slab. These commonly take the form of simple or complex metal sections or solid timber sections. In other applications, separate sills or hobs of similar form are sealing fixed to a said supporting surface and said building elements are fixed to and 20 supported by said sills or hobs. In yet other applications, concrete sills or hobs are formed on said cast in-situ concrete slabs to support said window frames, curtain wall panels and the like. In these applications, long box moulds which are more or less open at the top and bottom are fixed to concrete slabs in appropriate positions, filled with concrete and the 2 5 concrete allowed to cure. Said sills or hobs are then waterproofed

2014240183 24 Sep 2014 appropriately and said building elements then fixed to them. The separate forming of said sills or hobs on cast in-situ concrete slabs is inefficient and time consuming, requiring the re-attendance of several building trades personnel to a building site to accurately measure up and fix said moulds 5 in position and then to fill them with concrete. Additionally, irregularities in the trowelled surfaces of said cast in-situ concrete slabs may require the removal of concrete in order for said moulds to be set at the correct level. When it is considered that a multi-storey building may require several thousand lineal metres of such sills or hobs, the magnitude of the 10 inefficiency and loss of time will be appreciated. In a method taught by

Pantano in AU201127429, the fixing into position of sill or hob forming moulds is integrated into the process of fixing in place steel reinforcement bar preliminary to the pouring of concrete slabs, and the process of filling said sill or hob moulds with concrete is integrated into the process of the 15 in-situ casting of concrete building slabs. In this method, sill or hob moulds in the form of long boxes more or less open at the top and bottom are fixed into position during the process of installing reinforcing bar.

Said moulds are supported from formwork upon a row of discrete chairs which may be of fixed height or adjustable. During casting of the parent 2 0 concrete building slab, said moulds are simultaneously filled with concrete and trowelled off to a level surface, the concrete of the sill or hob so created thus being integral with that of said concrete building slab and thereby less prone to water infiltration; said sill or hob mould and said chairs being left in place in said concrete building slab after curing of said 2 5 concrete.

2014240183 24 Sep 2014

The object of the present invention is to provide a sill or hob moulding system in which the sill or hob created incorporates rebates of various forms, said rebates acting to make said sill or hob less prone to water infiltration by providing positive water draining paths towards the 5 exterior of a building.

According to the present invention, a sill or hob mould is assembled from two outer panels made in long lengths and maintained in a fixed, spaced-apart relationship by a plurality of narrow spacer pieces fixed to both. Said outer panels are also fixed to a plurality of spaced10 apart, generally upright attachment plates. Each said attachment plate is fixed to a horizontally-arranged supporting plate which is, in turn, fixed to the upper end of a said chair column. In the preferred embodiment, said attachment plates are formed from a single piece of suitable metal-alloy sheet material. Said chair columns are supported from the formwork built 15 to support said concrete building slab during the construction process, with the lower edge of said sill or hob mould set at the designed surface level of said concrete building slab. Said outer panels can be made in a variety of transverse cross-sectional shapes for a variety of purposes and for employment on the exterior or the interior of a building. Where there 2 0 is a possibility of water ingress, where example at the exterior of a building, the inner said outer panel is made with a raised or upwardlydirected part such that the remaining upper surface of said sill or hob, when moulded, is effectively rebated. Said raised part of said upper surface of said sill or hob effectively forms a dam positioned inwardly of 2 5 the inner surface of a window or curtain wall, said dam effectively acting

2014240183 24 Sep 2014 to direct any water entering said sill or hob towards to exterior of the building. Said chair and said sill or hob mould are positioned and secured in place supported from said formwork by personnel installing steel reinforcing bar. Said sill or hob mould is filled with concrete during pouring of said concrete building slab. Where circumstances require, provision is made to top mount a sill or hob mould by fixing it to the finished surface of a concrete building slab and separately filling it with concrete.

The various aspects of the present invention will be more readily understood by reference to the following description of preferred embodiments given in relation to the accompanying drawings in which:

Figure 1 is a diagrammatic, transverse, cross-sectional view of a chair and a sill or hob mould about to be united;

Figure 2 is a diagrammatic, transverse cross-sectional view of the components of Figure 1 united and supporting a window;

Figure 3 is a diagrammatic, transverse, cross-sectional view of a chair and a sill or hob mould united and fixed to the surface of a concrete building slab;

Figure 4 is a partial side view of means to fix the components of Figure 3 to the surface of a concrete building slab, said first and second outer panels shown deleted;

Figure 5 a is a first side view of a tool to set the fixing means of Figure 4;

Figure 5b is a second side view of the tool of Figure 5a;

Figure 6 is a fragmentary, transverse cross-sectional view

2014240183 24 Sep 2014 of alternative means to fix the components of Figure 3 to the surface of a concrete building slab;

Figure 7 is a side view of a moveable trough to facilitate filling of said sill or hob mould with concrete;

Figure 8 is a transverse cross-sectional view of a wall structure supported upon a sill or hob mould of the present invention;

Figure 9 is a diagrammatic, transverse cross-sectional view of a rebated sill or hob mould supporting a window;

Figure 10 is a diagrammatic, transverse cross-sectional view of a rebated sill or hob mould supporting a cavity brick wall;

Figure 11 is a diagrammatic, transverse, cross-sectional view of a chair and a sill or hob mould fixed to the surface of a concrete building slab;

The various figures are drawn to different scales and no inference should be drawn from this.

With reference to Figure 1, chair pillar 9 is securely welded to baseplate 14 which is, in turn, fixed to formwork built for creation of a cast-in-situ concrete building slab. The upper surface of said formwork is depicted as 12 and the positions of the fastenings fixing said baseplate to said formwork as 11. Transversely-arranged supporting plate 10 is securely welded to the upper end of each said chair column, the width of said supporting plate being more or less the same as the overall transverse width of the sill or hob mould to be supported on said chair. Longitudinally-arranged, parallel, upright attachment plates 6 are securely

2014240183 24 Sep 2014 welded to each said supporting plate. In the preferred embodiment, said attachment plates are made in the form of a single, U-shaped piece and securely welded to said supporting plate. The outer side of said sill or hob mould comprises a first outer panel la made in a long length, the upper and lower edges of said panel each being folded inwardly in two 90-degree bends to create upper return 2a and lower return 3 a, and upper attachment flange 4a and lower abutment flange 5a, the transverse cross-sectional shape of said first outer panel being more or less a simple rectangle. Upper return 2a serves as the outer part of the floor of said rebate. The inner side of said sill or hob mould comprises a second outer panel lb made in a long length and with a greater vertical height than said first outer panel, the upper edges of said second outer panel being first folded inwardly in two 90-degree bends to form upper return 2b and rebate edge 27, then folded back to a horizontal plane to create inner part of rebate floor 15 and then folded downwardly to create lower attachment flange 4b. The height of rebate edge 27 is more or less equal to the difference in height between said first outer panel and said second outer panel. The lower edges of said second outer panel are folded inwardly in two 90degree bends to create lower return 3b and lower abutment flange 5b. In the preferred embodiment, inner part of rebate floor 15 and upper return 2a (acting as the outer part of the floor of said rebate) are inclined downwardly in a common plane towards the outer face of said sill or hob mould, the angle of inclination falling in the range 0.5 to 2.0 degrees.

Said first and second outer panels are maintained in a parallel, fixed spatial arrangement by the secure welding of a plurality of

2014240183 24 Sep 2014 longitudinally spaced-apart, transversely-arranged spacer members to said lower abutment flanges. Depending upon the size and cross-sectional shape of said sill or hob mould, said transverse spacer members are made with a cross-sectional shape that is square, rectangular, irregular or a combination of such shapes, the transverse width of said spacer members being such that said separated mould side members just accommodate said attachment plates between them, lower returns 3a and 3b resting upon the exposed side edges of supporting plate 10. Said spacer members are optionally of open or closed form and taking the form of straight or bent rods, bars, struts, cruciform members, flat or corrugated plates, tubular sections or the like. The axial width (with respect to the longitudinal axis of said mould) of said spacer members is selected to ensure stiffness and, thereby, that said mould side members are united to form a rigid structure. Said spacer members are optionally fixed to said mould side members at any suitable inclination to the horizontal between 90 and 45 degrees.

With additional reference to Figure 2, with lower returns 3a, 3b resting upon the exposed upper surfaces of said supporting plate, fastenings (not shown) passing through apertures 13 provided towards the upper edges of said attachment plates are employed to fix upper attachment flanges 4a and 4b to said attachment plates, thereby effectively locking said mould to said chair. Said chair base plates 14 are then fixed in appropriate positions to said formwork (upper surface depicted as 12) using a plurality of suitable fastenings, typical positions of which are indicated in broken line as 11. In the preferred embodiment, said baseplate fastenings are ground away following their exposure by stripping

2014240183 24 Sep 2014 of said formwork, said sill or hob and its said mould being left in place in said concrete building slab. The axial widths of said supporting plate and said attachment plate (with respect to the longitudinal axis of said mould) are such that they provide minimal impediment to the flow of concrete 18 through said mould and down to said formwork. In the preferred embodiment, the surface of concrete 19 between rebate floor 15 and upper return 2a is finished to coincide with the angle of inclination of rebate floor 15 and upper return 2a. A plurality of suitably-spaced air bleed apertures 16 is optionally provided along the upper edge of rebate edge 27, said apertures permitting the escape of air during filling of said mould with concrete, any release of concrete from said apertures during said filling process being subsequently sponged away. Said apertures are concealed by the window, curtain wall or the like supported on said sill or hob. The upper surface of said concrete building slab (depicted as 17) is finished not lower than level with the lower edges of said outer panels, said filled mould being monolithic with said concrete building slab. Upper attachment flange 4b acts as a moisture barrier embedded in concrete 18. It is made of a suitable depth (vertical width) and acts to prevent any inward migration of moisture.

In the arrangement depicted in Figure 2, a window comprises a sheet of glass 26 sealingly supported in channel 23 of an extruded frame 25 and gasket 22 accommodated in said channel. In the preferred embodiment, the transverse cross-sectional shape of said frame is made in the form of a parallelogram such that sill 21 is made angled and more or less parallel with lower edge 20 which conforms to said angled surface of

2014240183 24 Sep 2014 said rebate. The angling of said sill promotes free drainage of water. The parallelogram shaping of said frame allows the inner and outer faces 24 of said frame to remain vertical. In the preferred embodiment, drip flange 28 is provided on the outer, lower edge of said window frame to facilitate drainage of water from said sill.

With reference to Figure 3, said sill or hob mould is fixed to the surface 17 of a concrete building slab 18 prior to being filled with concrete 29. In this embodiment, before pouring of concrete building slab 18, anchor plate 32 of anchor bar 30 is fixed to formwork (upper surface depicted as 12) by suitable fasteners (typical positions indicated in broken line as 33). Following pouring and trowelling of said concrete building slab, a suitable length of said anchor bar extends above said upper surface of said slab. In the preferred embodiment, the free, upper end of said anchor bar is folded to provide better engagement with concrete 29 with which said sill or hob mould is to be filled. With additional reference to Figures 4, 5a and 5b, domed, elastic disc 34 with axially-arranged, peripheral teeth 36 is frictionally secured at the upper end of said anchor bar while said concrete building slab is being poured. Said anchor bar passes through centrally-located aperture 37 in said disc, said aperture being permitted to expand slightly by two or more radially-arranged slots. Said aperture is not cylindrical, but is made tapering (reducing) in diameter towards its upper surface. Following curing of said concrete building slab, said sill or hob mould is positioned upon said concrete building slab and secured by driving down said disc such that said peripheral teeth engage the lower runs of spacer members 7. The tapered

2014240183 24 Sep 2014 arrangement of said aperture and the provision of said radially-arranged slots is such that said disc is able to be displaced downwardly on said anchor bar by the application of blows with the tool depicted at Figures 5 a and 5b, but strongly resists any upward movement. Said tool comprises an elongated handle part 36 terminating in a pair of parallel, arcuate impact surfaces 42 separated by a slot 38 of sufficient width to allow said anchor bar to pass between said impact surfaces. The tool permits heavy blows to be applied to said disc immediately adjacent said anchor bar, driving said disc into strong engagement with said spacer members. With said sill or hob mould fixed temporarily to said concrete building slab in the manner described, said mould is filled with concrete 29 which, when cured, locks said sill or hob strongly to said concrete building slab. With additional reference to Figure 6, in an alternative embodiment, said sill or hob mould is temporarily fixed to said concrete building slab by making suitablyspaced, transverse cuts in lower attachment flanges 5a and 5b, allowing strips of metal to be bent down flat through arc 40 to create tabs 39. Suitable fastenings are then passed through apertures 41 in said tabs, securing said sill or hob mould in place until it is filled with concrete 29, thereby locking it strongly to said concrete building slab. In the preferred embodiment, said fastenings take the form of hard nails driven by explosive, other power source or manual impact means.

With reference to Figure 7, rebated sill or hob mould 49 has raised part 50 separated from said rebated part by rebate edge 27. Filling trough 43 is slidingly supported on said rebated mould part, an elongated aperture in the lower part of said filling trough coinciding in width with the upper

2014240183 24 Sep 2014 opening into said sill or hob mould. Said trough has flange 45 formed around said elongated aperture, said flange having fixed to it a thick gasket of a compliant material, the face of said gasket being covered by a layer 47 of a thin, durable polymer material. A small, remotely-controlled concrete vibrator (not shown) is supported within said trough on elastomeric supports, energy being supplied to said vibrator via suitable conduit 48. Air bleed apertures 16 are provided at the upper edges of said rebate edge. Handles 44 are provided to facilitate manipulation of said trough. During filling of said sill or hob mould, said trough is positioned at one end of said mould and filled with concrete. Said vibrator is operated to liquidise said concrete which flows into said mould, air trapped in the raised part of said mould escaping via air bleed apertures 16. Said trough is slowly moved along said mould as it is progressively filled.

With reference to Figure 8, rebated sill or hob mould comprises two spacer members 53a, 53b tack-welded together and to which first outer panel 55 and second outer panel 56, made in long lengths, are tack welded, respectively, at upper and lower attachment flanges 4a and 5 a, and upper and lower attachment flanges 4b and 5b to create said sill or hob mould. Base plate 14 is securely welded to chair pillar 9 and transverselyarranged supporting plate 10 is securely welded to the upper end of said chair pillar. Said tack-welded assembly of said spacer members and said outer panels are fixed to said supporting plate by tack-welding, said assembly being retained in a suitable relationship with said supporting plate by means of suitable clamps. After suitable alignment, said chair pillars are fixed to said form work (formwork surface depicted as 12) by

2014240183 24 Sep 2014 suitable fastenings (typical positions indicated in broken line as 11). Said mould assembly is then filled with concrete 51 which is allowed to cure. Following curing of said concrete, typically, moisture barrier 54 is positioned to cover the whole of said mould. Proceeding with 5 construction of the building, a single-leaf brick wall 57 is built in said rebate and a stud wall is constructed on lower wall plate 58. Said stud wall is sheeted with plasterboard 59, a floor covering 61 is installed over the inner concrete surface and a skirting board 60 is fixed into place over said plaster board. In the embodiment depicted, said sill or hob mould, in 10 addition to creating a rebated hob, is also employed to create a break in level of said concrete building slab. In this application, a downwardlyextending skirt is optionally attached to said sill or hob mould to restrict any tendency for said concrete to flow beneath said mould.

With reference to Figure 9, a sill or hob mould comprises side 15 panels 62, 63 made in long lengths, the upper and lower attachment panels and 74 of which are tack-welded to a spaced-apart plurality of spacers 64. Said spacers are of any suitable transverse cross-sectional shape to suit the characteristics of said attachment panels and are orientated at any angle between 90 and 45 degrees in relation to the longitudinal axes of 2 0 said side panels. Second side panel 63 of said sill or hob mould is made with an elevated upper part 65 with a step 67 defining one side of a rebate. The upper, horizontal edge 66 of first side panel 62 defines the other side of said rebate. Said sill or hob is optionally made integrally with a concrete building slab in the manner described and is filled with the same 2 5 concrete 68 or is fixed to the surface of a concrete building slab and is

2014240183 24 Sep 2014 separately filled with concrete in the manner described. In the arrangement depicted in the figure, a window comprises a sheet of glass sealingly supported in channel 76 of an extruded frame 72 and gasket accommodated in said channel. In the preferred embodiment, drip flange 75 is provided on the outer, lower edge of said window frame to facilitate drainage of water from the sill of said window frame.

With reference to Figure 10, a sill or hob mould comprises first and second side panels 77, 78 made in long lengths, the upper attachment panels 80 and 81 of which are tack-welded to a plurality of spaced-apart upper spacers 64. The lower edges of said upper spacers are tack-welded to the upper edges of a plurality of lower spacers 80 which are, in turn, tack-welded to the interior surfaces of said side panels or to lower attachment panels 89. Said upper and lower spacers are of any suitable transverse cross-sectional shape to suit the characteristics of said attachment panels and, in their joined form, are orientated at any angle between 90 and 45 degrees in relation to the longitudinal axes of said side panels. First side panel 77 of said sill or hob mould is made with a rebated upper part 87 and with a raised upper part 86. Second side panel 78 is also made with a raised upper part 88 equal in height to raised upper part 86. Said sill or hob mould is optionally made integrally with a concrete building slab in the manner described and is filled with the same concrete 82 (as depicted in the figure) or is fixed to the surface of a concrete building slab and is separately filled with concrete in the manner described. In the arrangement depicted in the figure, the outer leaf of a cavity brick wall is supported upon rebate 87 and the inner leaf of said

2014240183 24 Sep 2014 wall is supported upon raised upper parts 86, 88.

With reference to Figure 11, a sill or hob mould comprises first and second side panels 90, 91 made in long lengths, the upper and lower attachment panels 93, 95, 94, 96 of which are tack-welded to a plurality of 5 longitudinally spaced-apart spacers 92. Said spacers are of any suitable transverse cross-sectional shape to suit the characteristics of said attachment panels and are orientated at any angle between 90 and 45 degrees in relation to the longitudinal axes of said side panels. In the embodiment depicted, joggle 96 is provided in said spacers to 10 accommodate the different upper and lower lateral distances between said side panels. Second side panel 91 of said sill or hob mould is made with a raised upper part 98 with a step 97 defining one side of a rebate. The upper, horizontal edge 99 of said first side panel 90 defines the other side of said rebate, said rebate being utilised to support any part of a structure.

In the embodiment depicted, said sill or hob mould is temporarily fixed to the surface of a concrete building slab 103 and is separately filled with concrete 104 in the manner described. Said sill or hob mould is permanently secured in place to said concrete building slab by a plurality of lengths of reinforcement bar 101 which are grouted into bores 102 in 2 0 said concrete building slab with suitable lengths left protruding upwardly from said building slab into said sill or hob mould. Filling of said sill or hob mould with concrete 100 acts to permanently secure said sill or hob mould to said concrete building slab.

Claims (6)

1. A permanent mould for forming a rebated sill or hob in poured in-situ concrete building slabs, the mould having at least a first side panel and a second side panel, the first and second side panels being maintained in a parallel, fixed spatial arrangement by a plurality of longitudinally spaced-apart, and transversely arranged, spacer members, the mould also having a plurality of supporting chairs, each supporting chair having a support plate configured to support the first side panel and the second side panel and/or the spacer members, and wherein the height of the rebate to be formed in the rebated sill or hob is determined by a difference between a height of the first side panel and a height of the second side panel, the second side panel height being greater than the first side panel height, and an axial width of each support plate, with respect to a longitudinal axis of the permanent mould, is such that the support plates provide minimal impediment to the flow of concrete through the permanent mould when in use, and at the time that the associated poured in-situ concrete building slab is poured.

2. A permanent mould for forming a rebated sill or hob in poured in-situ concrete building slabs as claimed in claim 1, wherein the supporting chairs each also include a base plate and a chair pillar, and the supporting plate of each supporting chair rests on its associated chair pillar.

3. A permanent mould for forming a rebated sill or hob in poured in-situ concrete building slabs as claimed in claim 1 or claim 2, wherein the upper and lower edges of the first and second side panels are folded through 90-degree bends to produce upper and lower returns.

4. A permanent mould for forming a rebated sill or hob in poured in-situ concrete building slabs as claimed in claim 1 or claim 2, wherein a width of each supporting plate is substantially the same as the overall transverse width of the spaced apart first and second side panels.

2014240183 14 Apr 2020

5. A permanent mould for forming a rebated sill or hob in poured in-situ concrete building slabs as claimed in any one of claims 1 to 4, wherein the first and second side panels are maintained in a parallel, fixed spatial arrangement by spacer members 5 that are welded to the side panels.

6. A permanent mould for forming a rebated sill or hob in poured in-situ concrete building slabs as claimed in any one of claims 1 to 5, wherein the transverse width of the spacer members is such that the spaced apart side panels just accommodate the 10 transverse width of the spacer members.