Screeding device and system

Abstract

 A screeding device (2) and system are disclosed. The device (2) comprises two pairs of limbs (4,6,8,10) each having distal (20,22,24,26) and proximal ends (12,14,16,18), the latter having apertures through which a first bolt (28) passes to mount the said limbs (4,6,8,10) thereto. The limbs (4,6,8,10) of each pair are mounted on the first bolt adjacent one another whereas each pair of limbs (4,6,8,10) are separated by a cylindrical spacer (32) also mounted on the bolt (28), and the manner in which the limbs (4,6,8,10) are mounted on said first bolt (28) permits their angular rotation both relative to one another and relative to the first bolt (28). The distal ends (20,22,24,26) of each pair are disposed on either side of the first bolt (28) when viewed from above to stabilise the device when disposed on a floor, and each of the distal ends (20,22,24,26) on both sides are linked by secondary spacer means (38,40). To effect the simultaneous and identical angular adjustment of the limbs (4,6,8,10) about the first bolt (28), a second bolt (54) having oppositely orientated threads (58,60) on either side of its mid point is received in suitably tapped apertures (46,50) in the secondary spacer means (38,40) so that the second bolt (54) is perpendicular to and passes underneath the first bolt (28). The rotation of the second bolt (54) thus either causes the simultaneous and identical angular displacement of the limbs (4,6,8,10) on either side of the first bolt (28), and in causing these limbs (4,6,8,10) to move towards or away from each other, the height of the uppermost surface of the device can be altered accurately and easily. The screeding system disclosed comprises a plurality of these devices connected by tubes attached to the free ends on the first bolts (28) which project at either end of the device to create rails which when aligned in parallel manner can support a screed levelling device for sliding motion thereover.

Description

[0001] This invention relates to a device and system which enables screed to be effectively laid prior to the mounting of tiles or indeed any floorcovering thereon to form a flat level floor in commercial premises having a large floor surface area.

[0002] It will be appreciated that although the following description is given with reference to the laying of screed over a large surface area and that the invention is most ideally suited for use in such areas, the invention is not to be considered as limited by the area of screed which is to be laid. For example the invention is equally applicable in circumstances where screed is to be laid over only a relatively small surface area.

[0003] For the purposes of the description of the invention, screed is to be taken as meaning any granular substance which has the characteristics more of soil than of a liquid and is thus capable of being spread and compacted, and specifically screed is often a moist mixture of sand and cement which is capable of setting and curing to provide a load bearing surface. The setting of tiles in sand/cement mixtures well known and desirable in premises where the completed tiled floor is to withstand substantial loads because there is complete contact between the bonding surface of the tile and the screed layer in which it is set.

[0004] The tiling of floors in commercial premises has been conventionally conducted by one of two methods. In the construction of modern commercial premises, such as supermarkets and the like, the floor is initially provided as a simple concrete bed. This invention is not concerned with the layer of concrete to form the floors, and therefore further description thereof is not provided except to mention that the surface of the concrete after setting is rarely sufficiently accurately flat, level and smooth.

[0005] Each of these terms has a specific meaning known in the trade in that flat means planar, level means horizontal, and smooth means the quality of the surface finish (texture) of the bed.

[0006] In a first method, the concrete is mechanically trowelled ("power floated") to provide a smooth surface which is not necessarily flat or level. When the concrete has then hardened, cured and dried, a layer of a synthetic adhesive compound is applied with a serrated trowel to the floor without particular reference to either the flatness or the level of the surface of the concrete bed, and tiles are simply pressed into the adhesive which cures thus setting the tiles. The results are often accordingly poor because the tiles merely adopt the contour and profile of the concrete bed and because the tiles have usually square edges, the uneven setting of the tiles over the concrete bed results in faceting whereby the edges of adjacent tiles are exposed in varying degrees and even very slight undulations in the concrete bed are accentuated and instantly visible in the completed tiled floor. The results of this method are thus rarely satisfactory in large commercial premises and this method is more appropriate for the tiling of small areas such as toilets, kitchens and bathroom floors.

[0007] In the second method, a layer of screed is firstly applied over the surface of the concrete bed and thereafter the tiles are embedded into the screed which subsequently sets to secure the tiles therein and provide the floor. The intention of applying a screed layer is to provide a smooth, accurately flat, and level surface in which the tiles can be laid and although simple conceptually, the method of providing such a screed layer method has a number of pervasive problems.

[0008] Firstly, it is to be mentioned that the screed is required to be laid over the entire surface of the concrete bed which may be an area of many hundreds of square metres, whereas the tiles are often only 150mm square and must be individually laid in a precisely uniform manner.

[0009] Thus the screed must be deposited in batches which can be covered with tiles before the screed hardens and therefore during the tiling over a concrete base, there will be a portion of the floor fully tiled and a portion not yet covered with screed. The fundamental difficulty with laying screed is therefore the maintenance of a uniform level over the entire surface area of the concrete bed as the quality, profile and contour of the concrete bed changes. In the vast majority of commercial premises, it is impossible to both cover the entire surface area of the concrete bed with screed and also place tiles thereon to cover same, and a means for ensuring a constant screed level over the many days which the tiling may take is required.

[0010] Means of achieving this aim are given in International Patent Application Nos. WO9415038, WO9311318, and WO9216701 all in the name of Combiform AB of Sweden. These various applications describe the use of perforated aluminium or steel sheets which are formed into longitudinal strip-like components having a profiled cross-sectional shape. Each component is provided with a pair of flanges on either side of a central upwardly extending web portion in which a resilient rib member can be received. Each of the flanges is perforated and each of the perforations can receive a threaded adjustment screw by which the component is ultimately supported prior to the screeding of a particular area.

[0011] In use, a pair of such components is used and the two components are placed parallel with each other and ideally with an end wall of the premises to be screeded, and each of the components is separated by a suitable distance. The separation distance between said components is limited by the amount of screed which is to be deposited therebetween and also, but more importantly by the physical strength of persons levelling the screed between said components as hereinafter described.

[0012] After the components have been roughly aligned, accurate measurements of the required level of screed over the entire premises floor are taken and the threaded adjustment screws provided intermittently in the flanges of the said components are adjusted to raise or lower the level of the resilient rib received in the upwardly extending web portion of said components. This adjustment is arguably the most critical step in screed laying in general because the adjustment is effected to ensure that the resulting screed is laid level over the entire surface area of the concrete bed. Any inaccuracies at this stage can have serious impact on the level of the completed floor as a whole, and furthermore errors in levelling may not be realised until a substantial portion of the floor has been screeded.

[0013] Accurate measuring devices such as theodolites, optical and laser height measuring devices are thus often employed to ensure that a consistent and repeatable level of screed is achieved each time the pair of components is laid on the floor. The adjustment screws by which the components are supported are screwed into or out of the flanges by predetermined amounts so that the level of each of the resilient rib members between which the screed is to be laid is at exactly the same height, and it will be appreciated that when screed is to be laid between a plurality of components connected together over a length of maybe 20 metres or more, the task is very time consuming and labour intensive. Furthermore, it is important to mention that the components described can bend slightly under even their own weight and therefore the intermittency of the adjustment screws must be sufficient to ensure that any bending deflection of the components, and thus varying in the level of the resilient rib is minimised.

[0014] It will be appreciated that over the entire length of the parallel components, often termed rails, between which screed is to be laid, there can be a great number of screws, and the raising or lowering of the level of either of the rails can be extremely lengthy on account of the need to turn every individual screw in each of the components connected together to form the rail by a predetermined degree.

[0015] Once the level of the components, and more precisely the resilient rib within said components has been accurately agreed upon and set, a screed hopper is then wheeled between the two components and deposits one or more loads of screed at suitable distances along the length of said components whereafter workmen can roughly distribute the screed between the two components. It is also to be mentioned that the propensity of said components to bend is exacerbated when the screed is distributed between and over said components. The weight of the screed on the components must also be taken into account when determining the intermittency of the adjustment screws provided in each of the flanges.

[0016] After the screed has been roughly distributed between the two said components, it is compacted and a screeding plank is disposed roughly perpendicular to each component and jostled so that it rests on the resilient ribs provided along the length of each component. An amount of screed is ideally disposed to one side of the plank so that when it is drawn along the ribs, the lower edge of said plank creates a level screed surface between the ribs.

[0017] It should be mentioned that when screeding in this manner there is a tendency for the final surface to finish slightly lower than the ribs. This is due to the uppermost grains of sand taking a rolling motion as they are dragged along by the said plank. The amount by which the screed finishes lower than the ribs is determined by and is proportionate to the grain size of the sand used which varies from one source to another. The process is then repeated until the entire concrete bed of the premises has been covered.

[0018] Notwithstanding the difficulty of accurately setting the level of the components, said components are not intended to be reused and retrieval would be severely disruptive as following removal, the partial void remaining would require to be filled with additional screed which would then have to be separately compacted and ruled off exactly flush with the adjacent finished work.

[0019] A yet further disadvantage is that if the components were to be reused it is extremely difficult to reset the level of said components after the screed has been laid between them because there is no means of establishing the particular location of the adjustment screws

[0020] As the said components are designed to be left to set within the screed there is a disadvantage in that as the screed may finish slightly lower than the top surface of the ribs which then in that case require to be ground or planed off to the level of the screed.

[0021] A major disadvantage in it not being intended to reuse the components is the high cost of the large number of components required to be purchased for each job.

[0022] A further disadvantage is the limited range of height adjustment provided for by said screws. To achieve any significant height adjustment, the pitch of said screws is required to be large, and therefore the screws themselves must be of both large diameter, and of a sufficient length so that a large enough height adjustment range can be obtained. However, the length of the screws cannot be so great such that when they are retracted to lower the level of the components, their uppermost surfaces rise above the level of the resilient rib over which the screeding plank moves. They would then interfere with the lower edge of the plank defining the screed level.

[0023] A still further problem is the interconnection of adjacent components to ensure that there is little or no hindrance given to the screeding plank when drawn over resilient ribs in the region of the connection. In general, the components are rarely specifically manufactured for a particular building but are provided in standard lengths and positioned in alignment adjacent one another. This causes difficulties when the screeding plank is drawn over the resilient ribs of respective components in the region where the two components mate.

[0024] It has been proposed that a set of different components having central webs which extend upwardly to a greater or lesser degree could be used, but in cases where the level of the concrete bed is highly uneven, a range of height adjustment of components may be required which is greater than that which can be provided by simply a single component.

[0025] It is an object of the invention to provide a levelling device and system of components therefor which is not affected by the above mentioned disadvantages.

[0026] According to the invention there is provided a device for screed levelling, said device comprising at least a pair of adjustable limbs having a free distal end and a proximal end through which a first bolt passes and being angularly adjustable thereabout characterised that the limbs are disposed on either side of said first bolt, said bolt being supported on the distal ends of said limbs and being raised or lowered as the limbs are angularly adjusted towards or away from one another.

[0027] The first bolt in the above statement of invention is to be taken to mean a component to which the limbs are pivotally connected and capable of angular displacement thereabout.

[0028] Preferably the first bolt further secures connector means on either side of said limbs to which tubes can be connected.

[0029] Preferably the distal ends of said limbs provide feet by which the first bolt is maintained a desired distance above said feet, and further preferably said first bolt also additionally passes through spacer means disposed between the proximal end of said limbs, said spacer means having similar cross-sectional shape and dimensions to said proximal ends of said limbs so as to be flush therewith and so that the uppermost surface of said device when supported on said feet is substantially smooth.

[0030] The angular adjustment of the limbs is achieved by means of a second bolt having oppositely orientated threads on either side of its mid point and passing through suitably tapped connection means provided on each limb remote from said first bolt, the rotation of said second bolt thus causing the angular adjustment of said limbs toward or away from each other about said first bolt.

[0031] It is yet further preferable that each of said limbs is provided with a pivotally connected peg proximate their distal ends having a tapped aperture therein through which said second bolt passes.

[0032] Preferably the pitch of the threads on either side of the mid point of said second bolt is identical so as to cause identical angular displacement of each of said limbs towards or away from each other.

[0033] Preferably said device is provided with two pairs of limbs, each limb having a distal end and a proximal end through which the first bolt passes, said first bolt also passing through spacer means which separate the first pair of limbs from the second pair of limbs.

[0034] Preferably the distal ends of each of said pairs of limbs are pivotally connected by secondary spacer means in which first tapped apertures are provided through which said second bolt passes.

[0035] Preferably said secondary spacer means are provided with second tapped apertures having axes approximately perpendicular to the axes of said first tapped apertures, adjustment screws being received in said second tapped apertures and supporting said device by their lowermost ends.

[0036] Preferably the secondary spacer means on one side of the device are of a different colour from those on the other side of the device to allow a user to instantly assess which way the second bolt should be turned to raise or lower the first bolt.

[0037] Preferably the connector means are provided proximate the ends of said first bolt and are in the form of cylindrical plugs capable of being frictionally received within the open ends of tubes to which said device is connected.

[0038] Preferably the plugs frictionally engage with the inner surfaces of said tubes and the outer surfaces of said tube are substantially flush with said first spacer means and the proximal ends of said limbs.

[0039] Preferably the spacer means and the proximal ends of the limbs are arcuate and preferably of substantially circular cross-section.

[0040] In an alternative aspect of the invention there is provided a screed levelling system comprising a first and second set of a plurality of devices as hereinbefore described connected by tubes, said first set and said second set adapted to be laid parallel to each other and over which a screed levelling device can be drawn to level screed disposed between said first set and said second set to a height above a concrete floor equal to the height of the uppermost arcuate surface of the devices above said floor.

[0041] Preferably the spacer means are of a nylon-based material.

[0042] Preferably the connector means are provided with shoulders against which the free end of the tubes connected thereto abut, said shoulders in turn abutting the respective sides of the proximal ends of the said limbs.

[0043] It will be appreciated that the raising and lowering of the devices and thus the desired screed level can be effected very quickly and simply by virtue of the connection of the limbs on either side of the first bolt. The simple rotation of the bolt connecting the limbs causes immediate raising or lowering of the effective screed level and the interconnection of the devices by tubes ensures that there is minimal disturbance of the laid screed when the system is pulled up from the screed bed and reused.

[0044] It is important at this stage to distinguish between the systems of the prior art described above which are not reusable and the present invention which had as one of major objects the provision of a screeding system with inherent long-term reusability. All the components of the system are provided with some protection against corrosion through contact with chemically active moist screeds, for example through plastic coating/galvanising of the tubes between which the supporting adjustment devices are connected, or through careful selection of the materials from which the various parts constituting the supporting devices are manufactured, e.g. plastics materials, stainless steels and the like.

[0045] The use of tubes which are connected to each of the devices ensures also that there is no significant bending thereof between the devices due to the weight of screed because the majority of said screed is disposed underneath the said tubes. The tubes are flush with the connectors on the devices which are in turn flush with the spacer means and the proximal ends of the limbs, and therefore there is practically no hindrance whatsoever as the screed levelling device is drawn across the devices and tubes in the region of the connections thereof.

[0046] A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings, wherein:

[0047] Figure 1 shows a perspective view of a device according to the invention, Figure 2A shows a side elevation of the device of Figure 1 in an elevated position, and Figure 2B shows schematically how the device of Figures 1, 2A is connected to tubes to provide a screed levelling system.

[0048] Referring firstly to Figure 1 there is shown a device 2 having pairs of limbs 4, 6 and 8, 10 respectively. Each of said limbs is provided with a proximal end 12, 14 and 16, 18 and a distal end 20, 22, and 24, 26 respectively. A bolt 28 passes through apertures provided in the proximal ends of said limbs after first passing through a first connector plug 30, a spacer 32 and a second connector plug 34. A nut 36 or other suitable means of ensuring that the various components connected together on said bolt is provided, and the length of the bolt, the width of each of the various components connected together on said bolt and the length of the threaded portion of said bolt at its free end are such that the components are all rigidly connected together about said bolt but not so tightly as to be prevented from rotating relative to one another.

[0049] The plug connectors 30, 34 are provided with shoulders 42, 44 against which the edges of tubes 100 are abutted during the connection of the devices to said tubes (see Figure 2B).

[0050] At the said distal ends of the limbs, second spacer means 38, 40 are connected to on the one hand to provide wide supporting feet portions and on the other hand to ensure that the distal ends of said limbs are maintained a uniform distance from one another under all conditions.

[0051] Within each of said spacers 38, 40 there are provided a pair of apertures 46, 48 and 50, 52, the axes of apertures 46, 50 being approximately perpendicular with the axes of apertures 48, 52. The first of these apertures 46, 50 receives a second bolt 54 therethrough and this bolt 54 passes directly beneath the spacer 32. The bolt 54 has a central unthreaded portion 56, and two threaded portions 58, 60 which are ideally of identical length and pitch, the exception being that the orientation of the threaded portions 58, 60 is opposite.
In the configuration shown in Figure 1 which is approaching the lowest position of the device, the limbs are almost parallel and the central section 56 of the bolt 54 is a short distance from contacting the under side of the said space 32. Additionally, the spacers 38, 40 are almost at the extremities of the threaded portions 58, 60 near the heads 62, 64 of said bolt. It is to be mentioned that in the lowest position, the bolt simultaneously contacts the underside of the spacer 32 and the spacers 38, 40 are prevented from travelling any further along the threaded portions 58, 60 by their abutment with the heads 62, 64.

[0052] Adjustment screws 66, 68 are provided in the apertures 48, 52 and because the spacers 38, 40 do not rotate as the bolt 54 is adjusted to bring the limbs towards one another, the screws 66, 68 remain vertically orientated within said spacer means. This can be seen in Figure 2A.

[0053] The opposite orientation of the threaded portions 58, 60 on the bolt 54 ensures that the angular displacement of the limbs relative to the bolt 28 is identical, and thus said limbs approach one another at the same rate. In the situation where the device is connected to tubes 100 as shown in Figure 2B over which a screed levelling device such as a plank of wood is to be drawn, the provision of a single bolt coupled to both pairs of limbs through the spacers 38, 40 automatically effects an angular adjustment of both limbs and thus raises the effective height of the device, being the height of the uppermost arcuate surface of the device.

[0054] It is also to be noted that uppermost arcuate surface of the device and the uppermost arcuate surface of the said tubes 100 are flush and create a smooth surface over which the screed levelling device can be drawn.

[0055] In Figure 2B, a pair of rails 102, 104 created from tubes 100 and devices 2 connected thereto, and in use, screed will be deposited between such a pair of rails positioned apart from one another by a suitable distance. The firm support provided by the devices for the tubes and the fact that the tubes are raised above the concrete floor of the premises being screeded contribute to the advantage of this device in that firstly the devices and system as a whole can withstand the forces to which they may be subjected and the rigours of aggressive environments such as building sites, and secondly excess screed will pass underneath the tubes as opposed to collecting above same, and therefore the screed layer can be maintain level even remote from the devices supporting said tubes.

[0056] Ideally the tubes are constructed of steel with a wall thickness sufficient to create the rigidity required to resist bending between the devices. The steel tubes should be coated to resist corrosion, either by being galvanised or coated with a resilient plastics material, brightly coloured so that it is immediately evident where the devices 2 are located. In a specific embodiment, the tube is a steel gas pipe having an outer diameter of 28mm and wall thickness of 3mm which has found to provide sufficient rigidity to prevent bending of the tube during use. A substantial red lead internal coating is provided to inhibit corrosion and most preferably the tube is additionally internally and externally galvanised.

[0057] After levelling of the screed has been completed between a respective pair of rails (which incidentally can be as long as required and certainly longer than 20m), a pair of thin lines will thus just be visible through the particular layer of screed and at either edge thereof (i.e. where the tubes have been revealed as the screed levelling device has passed thereover.) The interruptions in these lines indicate the location of the devices.

Claims

1. A device for screed levelling, said device comprising at least a pair of adjustable limbs having a free distal end and a proximal end through which a first component passes, said limbs being connected to said component in a manner which permits angular adjustment of said limbs relative to one another about said component, characterised that the limbs are disposed on either side of said first component to provide support for the component when the device is disposed on a floor by virtue of the contact of said distal ends with said floor, said limbs being angularly adjustable towards or away from each other to raise or lower said first component.

2. A device according to claim 1 characterised in that the first component extends through apertures provided in the proximal ends of the limbs.

3. A device according to claim 2 characterised in that connector means are mounted on the portions of the first component which extend on either side of side apertures of said limbs to permit the connection of tubes thereto.

4. A device according to any preceding claim characterised in that spacer means are provided on said first component to separate said limbs axially of said first component.

5. A device according to claim 4 characterised in that said spacer means having a similar radius of curvature as the proximal ends of said limbs so as to be flush therewith and so that the uppermost surface of said device when supported on said feet is substantially smooth.

6. A device according to any preceding claim characterised in that angular adjustment of the limbs relative to one another and relative to the first component is achieved by means of a second bolt having oppositely orientated threads on either side of its mid point and passing through suitably tapped connection means provided proximate the distal ends of each limb remote from said first component, the rotation of said second bolt thus causing the simultaneous angular adjustment of said limbs toward or away from each other about said first component.

7. A device according to claim 6 characterised in that each of said limbs is provided with a pivotally connected peg proximate their distal ends having a tapped aperture therein through which said second bolt passes.

8. A device according to claim 6 or 7 characterised in that the pitch of the threads on either side of the mid point of said second bolt is identical so as to cause identical simultaneous angular displacement of each of said limbs towards or away from each other.

9. A device according to any preceding claim characterised in that said device is provided with two pairs of limbs, each limb of each pair having a distal end and a proximal end through which the first component passes, and the distal ends of the limbs of each pair being disposed on opposite sides of said first component.

10. A device according to claim 9 characterised in that the first and second pair of limbs are adjacently mounted on said first component with each pair being separated by intervening spacer means.

11. A device according to claim 9 or 10 characterised in that secondary spacer means are pivotally connected to the distal ends of the each pair of limbs on either side of the first component.

12. A device according to claim 11 characterised in that said secondary spacer means are provided with first tapped apertures through which said second bolt passes.

13. A device according to claim 11 or 12 characterised in that said secondary spacer means are provided with second tapped apertures having axes approximately perpendicular to the axes of said first tapped apertures to receive adjustment screws one end of which projects above the secondary spacer means to allow for rotational adjustment thereof, the alternate free end projecting below said secondary spacer means to provide a support for said device.

14. A device according to any of claims 11-13 characterised in that the secondary spacer means on one side of the device are of a different colour from those on the other side of the device to allow a user to instantly assess which way the second bolt should be turned to raise or lower the first component.

15. A device according to claim 3 and any claim dependent thereon characterised in that the connector means are provided proximate the ends of said first component and are in the form of cylindrical plugs capable of being frictionally received within the open ends of tubes to which said device is connected.

16. A device according to claim 15 characterised in that the plugs frictionally engage with the inner surfaces of said tubes and the outer surfaces of said tube are substantially flush with said first spacer means and the proximal ends of said limbs.

17. A device according to claim 5 and any claim dependent thereon characterised in that the spacer means and the proximal ends of the limbs are arcuate and preferably of substantially circular cross-section.

18. A device according to claim 4 and any claim dependent thereon characterised in that the spacer means are of a nylon-based material.

19. A device according to claim 3 and any claim dependent thereon characterised in that the connector means are provided with shoulders against which the free end of the tubes connected thereto abut, said shoulders in turn abutting the respective sides of the proximal ends of the said limbs.

20. A screed levelling system comprising a first and second set of a plurality of devices according to any of claims 1-19 connected by tubes, said first set and said second set adapted to be laid parallel to each other and over which a screed levelling device can be drawn to level screed disposed between said first set and said second set to a height above a concrete floor equal to the height of the uppermost arcuate surface of the devices above said floor.

Drawing