GB2580019A

GB2580019A - Adjustable staircase

Info

Publication number: GB2580019A
Application number: GB1818895.3A
Authority: GB
Inventors: Eric Manser Richard
Original assignee: Safesite Isle Of Wight Ltd
Current assignee: Safesite Isle Of Wight Ltd
Priority date: 2018-11-20
Filing date: 2018-11-20
Publication date: 2020-07-15
Also published as: GB201818895D0

Abstract

The adjustable staircase comprises a plurality of treads T fixable at a plurality of different angles between a pair of stringers. Fixing holes may be provided in the stringers and in both ends of each tread. When respective holes in a stringer and tread are aligned, a bolt can be passed through the holes and fastened with a nut to fix the tread to the stringer. This enables a fixing angle to be selected such that the treads are substantially horizontal, independently of the slope of the stringers. A foot piece FP may be fixable at a plurality of positions along the lower end of each stringer, the length from a top end of each stringer to a ground engaging portion of each foot piece being adjustable. Each stringer may be constructed from multiple stringer plates SP5, SP6 joined by joining plates JP. Each foot piece may define a specific or variable angle of rise for each stringer. The staircase may be dismantleable and reconstructable. Also claimed is a kit comprising stringer plates, joining pieces for assembling the stringer plates into a pair of stringers, foot pieces, treads, and a landing catch plate LCP.

Description

ADJUSTABLE STAIRCASE

The present application relates to an adjustable staircase, for example for use on building sites to enable a person to move from one floor to another floor of a property under construction.

When a building with more than one floor level (storey) is being constructed, there is a need for tradespersons to move between floors inside the building. However, the final internal staircase is often one of the last items to be constructed in order to avoid it being damaged by the passage of people, tools and materials while the property is being constructed. Traditionally ladders have been used temporarily to enable movement between floors. However, ladders are inconvenient to use when carrying tools and materials because they are required to be placed at a steep angle and have small treads, in fact, the use of ladders in such circumstances is increasingly being prohibited under health and safety regulations. An alternative is to use scaffolding, but that can be heavy and bulky to transport, difficult to erect in a confined space, comes in fixed sized and shaped units, and requires specialist contractors to erect and dismantle, So there are problems with providing a temporary staircase that can fit any height difference between floors while remaining within a permitted range of slope angle, as well as keeping the treads substantially horizontal. There arc also problems with making the staircase convenient to transport and to construct/deconstruct.

The present invention has been devised in view of the above problems.

Accordingly, one aspect of the present invention provides an adjustable staircase comprising: a pair of spaced apart stringers; and a plurality of treads fixable between the stringers, wherein each tread is fixable at a plurality of different angles with respect to the stringers.

Another aspect of the invention provides a kit of parts for an adjustable staircase according to the above aspect of the invention, comprising: a plurality of stringer plates; a plurality of joining pieces for assembling the stringer plates into a pair of stringers; a plurality of foot pieces; a plurality of treads; and a landing catch plate.

A further aspect of the invention provides a method of constructing an adjustable staircase comprising: I 0 fixing a landing catch plate to an upper floor level; attaching a pair of stringers to a top tread that is fixed to the landing catch plate; selecting foot pieces and attaching one to the lower end of each stringer to define a desired angle of rise of the stringers and to define the length from a top end of each stringer to a ground engaging portion of each foot piece and fixing a plurality of treads between the stringers, whereby the angle at which the treads are fixed is selected to be substantially horizontal With embodiments of at least some aspects of the invention, the length and slope of the staircase can be adjusted to suit the vertical height between floors, while maintaining the slope within the range permitted by the relevant regulation, and maintaining the treads substantially horizontal, i.e. deviating from horizontal by only a small angle at most, such as less than 2 degrees.

Further optional aspects of the invention are defined in the dependent claims.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 shows an adjustable staircase according lo an embodiment of the invention in situ in a building under construction; Fig. 2 shows the staircase of Fig. 1 with annotations; Fig. 3 shows a landing catch plate and top tread installed during the construction of the staircase of Figs. 1 and 2; Fig. 4 is a perspective sketch of the end portion of the landing catch plate; Fig. 5 is a plan view,from the underside, of a tread of the staircase;

S

Fig. 6 illustrates a stringer plate for four treads; Fig. 7 illustrates a stringer plate for six treads; Figs. 8(a), 8(b), and 8(c) illustrate a joining plate and two stringer plates; Fig. 9 illustrates a foot piece with a 48 degree slope angle; Fig. 10 illustrates a foot piece with a 52 degree slope angle; Fig. 10(a) illustrates a p votable foot piece with a variable slope angle; Fig. I I is a sketch of the end of a tread; Fig. 12 is a sketch of a stringer plate illustrating the position of the tread fixing holes; Fig. 13 illustrates the foot portion of the constructed staircase of Figs. 1 and 2; and Figs. I4(a) and I4(b) are illustrations of a further staircase according to another embodiment of the invention.

In the drawings, like parts arc indicated wiLh like reference signs, and duplicaied

description thereof is avoided.

An embodiment of the invention is explained firstly with reference to Figs. 1 and 2. Labels have been omitted from Fig. 1 for clarity, but parts are annotated in Fig. 2. The illustrated staircase has a number of treads T and runs from a lower floor level to an upper floor level. The upper end of the staircase is fixed to a joist J of the upper floor by means of a landing catch plate LCP, described in more detail below (and referred to simple as a catch plate). Each lateral side of the staircase comprises a stringer; the stringers are spaced apart by the treads, and the stringers support the treads. In this specific embodiment, the stringer on the right hand side comprises a lower stringer plate SP6 that accommodates six treads, and an upper stringer plate SP5 that accommodates five treads. The stringer plates are joined by a joining plate JP. The stringer on the left hand side comprises the same components, but for clarity, only the stringer on the right hand side has been labelled. At the bottom end, each stringer is joined to a foot piece FP that rests on the lower floor surface. I0

The components of the staircase will now be described in more detail in conjunction with an explanation of how to construct and install the staircase.

Firstly, the catch plate LCP is fixed to the joist J, as shown in Fig. 3. The catch plate LCP comprises an inverted L-shaped section with a vertical plate 10 and a horizontal plate 12, shown in Fig. 4. Projecting horizontally from the vertical plate 10 is a tread support plate 14. The edges of the plates are welded together, and triangular fillet pieces 16 are welded between the vertical plate 10 and the tread support plate 14.

In this embodiment, all of the plates of the catch plate LCP are 700 mm long. The vertical plate 10 and the tread support plate 14 are each 150 mm wide/high, and the horizontal plate 12 is 90 mm wide. Holes arc provided in the plates 10 and 12 to enable the catch plate LCP to be fixed by screws, both horizontally and vertically, to the joist J (Fig. 3).

All of the plates forming part of the staircase in this embodiment (described above and below) are made of metal, for example mild steel, such as S275JR grade, and are 6mm thick. The metal can be galvanized or otherwise treated for corrosion resistance. Of course, different thicknesses and materials can be used as desired.

A tread T is illustrated in Fig. 5. The tread T comprises an open rectangular frame F 700 mm x 210 mm, made of metal plate, and with a height of 30 to 50 mm, such as 40 mm. The interior of the frame is provided with a welded grid or mesh of slats and/or wires G. This open grid structure provides a non-slip surface that is rigid, but easy to keep clean. On the underside at each end of the tread is a welded rectangular plate P, for example 50 mm wide, to provide additional strength and rigidity. A hole FIX is provided in each of these plates P (at least for the top tread of the staircase), by which the tread T is bolted to the catch plate LCP via corresponding holes HY in the horizontal plate 14.

When the tread T is bolted to the catch plate LCP, the top of the tread is substantially flush with the top surface of the horizontal plate 12. The leading edge 18 of the horizontal plate 12 is preferably chamfered, as shown in Fig. 4, at an angle such as 15 degrees, to avoid presenting a trip hazard. I0

Next the stringers are constructed. Two example stringer plates SP4 and SP6 are illustrated in Figs. 6 and 7, which are for accommodating four and six treads, respectively. However, it is envisaged that a kit of parts for a staircase can be provided with stringers to suit any number from one to eight treads. The sets of holes for fixing the stringer to each of the treads arc indicated by HT. At the lower end of each stringer plate is a set of holes HJ for jointing the stringer plate to another item (e.g. joining plate or foot piece described below). The stringer plates are also provided with optional sets of holes HH for fixing a handrail structure to the stringer.

The stringer plates SP4 and SP6 in Figs. 6 and 7 arc not shown to scale with each other. In this embodiment of the invention, both stringer plates are formed from metal strips 150 mm wide and 6 mm thick. The ends of the plates arc at an angle so that the stringer plates are in the form of a parallelogram (in this embodiment, the angle of the parallelogram is 48 degrees). The spacing along the length of each stringer plate between successive corresponding holes HT for fixing the treads is constant (in this embodiment is 300 mm), so longer and shorter stringer plates are essentially identical to those illustrated, just with more or fewer sets of tread fixing holes HT. In this embodiment, a stringer plate to accommodate eight treads is roughly 2500 mm long (300 mm spacing per tread plus a bit more because of the parallelogram shape).

Greater lengths become difficult to handle, transport and store, so multiple stringer plates can be joined together as explained further below.

As mentioned, the spacing along the length of a stringer plate between sets of holes HT for fixing the treads in this embodiment is 300 mm. However, in use, the stringers are inclined at a slope angle with respect to the horizontal. The typical slope angle in this embodiment is 48 degrees. This means that the vertical rise from one tread to the next on a completed staircase is around 225 mm. So to select/construct a stringer, the total height rise from the lower floor surface to the upper floor surface is divided by the vertical rise from one tread to the next, and is rounded down to give an integer for the number of treads that will be used. This is a general formula for any embodiment..

For example a 2500 mm height difference, divided by 225 mm rise per tread, gives 11.11; so a stringer with 11 treads will be required. As shown in Fig. 2, this can be obtained by using a six-tread stringer plate SP6 and a five-tread stringer plate SP5.

To join two stringer plates together, a joining plate JP is used, as will be described with reference to Figs. 8(a), 8(b), and 8(c). The joining plate JP is essentially similar to a short stringer plate in terms of material and construction. Example upper stringer plate SPU and lower stringer plate SPL are shown, and their ends are brought into abutment. The joining plate JP is then placed on top or underneath such that the joining holes HJa on the joining plate JP align with the joining holes HJb on the upper stringer plate SPU; and such that the tread fixing holes ITTal, ITTa2, and HTa3 on the joining plate JP align with tread fixing holes HTbl, HTb2, and HTb3, respectively, on the stringer plates SPU, SPL. The joining plate JP and stringer plates SPU, SPL are then fixed together using suitable fixing means, for example a nut and bolt, through each of the aligned pairs of holes. The holes in the joining plate in a preferred embodiment are slightly elongated, for example by 25%, along the length of plate, to assist in achieving alignment of the holes without demanding too tight a tolerance in the fabrication of the plates In a later construction step, some of the bolts will need to be temporarily removed to enable the treads to be bolted in place; however if only one tread at a time is done, the stringer maintains its structural integrity because there is plenty of redundancy with the multiple fixings between the joining plate JP and the stringer plates.

Two stringers of the same length are constructed, one for each side of the staircase, with the joining plates preferably located on the laterally outer side in each case so that the inner side of the stringers does not have any step changes in the surface.

A foot piece FP, as shown in Fig. 9, is bolted to the lower end of each stringer (see Fig, 2). The foot piece FP comprises a parallelogram plate PP (similar to a stringer plate) and a base plate BP, welded together. The parallelogram plate PP in this embodiment rises at an angle of 48 degrees from the horizontal base plate BP. The parallelogram plate PP has multiple pairs of holes for aligning with the lower holes of the joining holes HJ of the bottom stringer plate, and multiple pairs of holes for aligning with the lower tread fixing holes HT of the bottom stringer plate.

The top end of each stringer is then bolted to the tread T that has been fixed to the catch plate LCP, by means of the top tread fixing holes HT and corresponding holes in the side of the tread. The stringers may initially be loosely bolted, provisionally at 48 degrees, or may be bolted using a bolt in only the front hole, so that the stringers can pivot slightly while other adjustments are made. The length of the stringers is adjusted by changing the fixing of the foot pieces to achieve the desired slope angle of approximately 48 degrees with the base plates BP in contact with the lower ground surface. in this embodiment, multiple sets of holes are provided for five different length positions for each foot piece. The spacing between successive holes along the length of the parallelogram plate is approximately 35 mm, which means that the height rise of the staircase stringers can be adjusted in increments of approximately 25 mm. If the length cannot be adjusted to achieve a slope angle of roughly 48 degrees (or if the gap from the bottom tread position to the lower ground surface would be too great), then the staircase can be inclined at a slightly steeper angle of 52 degrees from the horizontal. This is achieved by using a foot piece FP2, illustrated in Fig. 10, which is generally of the same construction as the foot piece FP of Fig. 9, except that the parallelogram plate PP rises at an angle of 52 degrees from the base plate BP (and the tread fixing holes are different, as explained further below), in the second foot piece FP2, the parallelogram plate PP is not a perfect parallelogram because the angle where it meets the base plate BP is 52 degrees. but the angle at the other end can be 48 degrees for consistency with the stringers and other components.

Fig. 10(a) shows an alternative embodiment of a foot piece FP in which the plate PP, which is provided the with holes for fixing to the lower end of the stringer, but need not be a parallelogram, is pivotable with respect to the base plate BP, rather than being welded at a fixed angle. In this embodiment, one or more upright plates UP are welded to the base plate BP, and the plate PP is pivotable about the axis of a shaft of a member SH joining the upright plate UP and the plate PP. This alternative foot piece FP can be used with any of the embodiments of the invention described herein.

The stringers are fixed to the tread T at the top (the tread fixed to the catch plate LCP), with reference to Figs. 11 and 12, as follows. Fig. 11 shows the end of the tread T with three holes HI. H2 and H3, in a line across the middle of the end plate of the tread, in this embodiment, the spacing between HI and H2 is roughly 80 mm, and the spacing between Hi and H3 is roughly 120 mm. Fig. 12 shows schematically a stringer plate SP. The set of tread fixing holes HT at the upper end of the stringer plate SP comprises holes HT1, HT2, and HT3. Holes HT1 and HT3 are at the same spacing as holes HI and H3. The line joining the centres of the holes HT1 and HT3 is parallel to the end of the stringer plate (so in this embodiment that line is inclined at 48 degrees to the long edge of the stringer plate). If the stringer plate SP is bolted to the tread T by aligning holes HI and HT1, and aligning holes H3 and HT3, and passing a bolt through the aligned holes and fixing with a nut, then the stringer runs at an angle of substantially 48 degrees to the horizontal (assuming the tread T is fixed horizontally). Holes HT1 and HT2 are at the same spacing as holes H1 and H2.

However, hole HT2 is located slightly below the line joining the centres of the holes HT1 and HT3. So the line joining the centres of the holes HTI and HT2 forms an angle A with the line joining the centres of holes HT1 and HT3. In this embodiment, angle A is approximately 4 degrees. if the stringer plate SP is bolted to the tread T by aligning holes H1 and HT1, and aligning holes H2 and HT2, and passing a bolt through the aligned holes and fixing with a nut, then the stringer runs at an angle of substantially 52 degrees to the horizontal (assuming the tread T is fixed horizontally).

in this way, by selecting the slope angle of the stringers, and adjusting the length of the stringer by the positioning of the foot piece, the staircase can be made to suit any height change required, while still keeping the slope angle within a prescribed range.

Having adjusted the foot pieces and fixed the stringers to the top tread, the remaining treads can now be fixed in place, working up from the bottom. This can be done by one person alone, and without requiring any ladders, because as the lower treads are fixed in place, they can be stood on to provide access to the higher tread positions. All of the treads are fixed using a bolt through the front hole H1 and through the tread fixing hole HT1 in the stringer (Figs. 11 and 12). The tread is then kept substantially horizontal by aligning either holes H3 and HT3, or holes H2 and HT2, and securing a bolt therethrough, depending on the slope of the staircase stringers.

In an alternative embodiment, the stringers can be pivotably fixed to the top tread or to the catch plate, for example using a bolt or hinge, to allow some variation in the slope angle (angle of rise) of the stringers, but the remaining treads can be fixed at discrete angular positions as illustrated in Figs. I 1 and 12, such that the treads are substantially horizontal.

Fig. 13 shows the lower portion of a completed staircase, using a foot piece FP2 and a stringer at a 52 degree angle. In this case, the bottom tread is fixed to the lower stringer plate and to the foot piece using the holes HI with HT I, and H2 with HT2, plus corresponding holes in the foot piece FP2.

The base plate BP comprises the ground engaging portion of the foot piece FP. The base plate BP of this or any other embodiment can be provided with holes to enable it to be screwed to the lower ground floor surface for rigidity, if desired. The base plate BP of each foot piece is typically 150 mm wide by approximately 200 mm long and 6 mm thick.

Lastly, hand rails can, if required, be fitted to the staircase by means of holes HH provided in the stringers for securing suitable mounting brackets The staircase can be dismantled by following the above procedure in reverse. Construction/deconstruction can be performed by a single person, and the component parts can conveniently be transported inside a vehicle, such as a builder's van.

Figs. I4(a) and 14(b) show a further embodiment of the invention. In this embodiment an intermediate landing level is provided, constructed from a square grid supported on four legs. The actual flights of stairs are constructed as described above, and are fixed to the intermediate landin2, for example using nuts and bolts through the treads. In the example illustrated, the staircase forms a dog-leg, turning through 90 degrees at the intermediate landing. However, it could equally be constructed as a straight pair of flights entering and leaving on opposite sides of the intermediate landing In the above-described embodiments, the holes for use when bolting the components together are preferably 13 mm in diameter when initially drilled in the metal, such as mild steel, or 13 mm by 16 mm if slightly slotted to aid alignment; however different dimensions can be used, and the holes HH for fixing hand rails can be of a different size from the other holes. If the components are galvanized after fabrication (before assembly), there will be a slight reduction in the internal dimensions of the holes. It has generally been described that the components are fixed together using nuts and bolts; preferably the bolts are M12, and using this size allows dome clearance margin even if the holes have been reduced slightly in diameter by galvanizing the other components. It is envisaged that any known variants of nuts and bolts and associated hardware could be used, such as hexagonal heads for use with a spanner, hexagonal recesses for use with an alien key, load spreading heads or washers, locking nuts or washers. it is also envisaged that any suitable alternative undoable fixing means can be used instead of nuts and bolts.

The above embodiments use a primary staircase slope angle of 48 degrees or 52 degrees merely as a preferred example; the components can be fabricated to suit any appropriate angles, such as in the range from 40 degrees to 60 degrees, or 45 degrees to 55 degrees, and can have more than two possible angles.

As illustrated in Figs. 11 and 12, the holes HI, 1-12, and H3 in the end of the tread are provided in a straight line, and the tread fixing holes HT1. HT2, and HT3 in the stringer plate are not in a straight line. However, the components could be constructed the other way round, with the holes in the stringer plate in a straight line, and one of the holes in the tread end slightly off-set. However, it is preferred to have the holes in the tread end in a straight line because the positioning is more constrained by the thickness of the tread.

Regarding the tread fixing holes HTI, HT2, and HT3 in the stringer, making the holes HT2 and HT3 off-set from each other across the width of the stringer plate avoids introducing weakness in the stringer plate, if these holes HT2 and HT3 were provided on a single arc centred on the hole Fill, then they would either be very close or overlapping. It is also envisaged that more holes could be provided in the tread and stringer plate to allow adjustment between more than just two angles of the tread relative to the stringer plate.

Although the above embodiments of the invention have been described for providing access between floor levels when constructing a building, embodiments of the invention can also be used for any suitable staircase applications, such as for use as a temporary fire escape.

Claims

CLAIMSAn adjustable staircase comprising: a pair of spaced apart stringers; and a plurality of treads fixable between the stringers, wherein each tread is fixable at a plurality of different angles with respect to the stringers.
2. An adjustable staircase according to claim 1, wherein the plurality of angles are I 0 between 40 and 60 degrees relative to the length of the stringers.
3. An adjustable staircase according to claim 1 or 2, wherein multiple fixing holes are provided in the treads to suit corresponding holes in the stringers, and wherein fixing a tread at a first angle involves using at least one different hole in both the tread and the stringer from fixing the tread at a second angle.
4. An adjustable staircase according to claim 3, wherein fixing a tread at a first angle involves using at least one hole in both the tread and the stringer in common with fixing the tread at a second angle.
5. An adjustable staircase according to any preceding claim, further comprising a foot piece fixable at a plurality of positions along the lower end of each stringer, whereby the length from a top end of each stringer to a ground engaging portion of each foot piece is adjustable.
6. An adjustable staircase according to any preceding claim, wherein each foot piece defines one of: a specific angle of rise for each stringer, or a variable angle of rise for each stringer.
7. An adjustable staircase according to any preceding claim, wherein each stringer comprises multiple stringer plates, each shorter than the total length of the stringer, fixed together to provide the total length of each stringer.
8. An adjustable staircase according to claim 7, wherein the stringer plates are fixed together by means of joining plates overlapping adjacent stringer plates.
9. An adjustable staircase according to any preceding claim, further comprising a landing catch plate securable to an upper floor level, wherein a tread is fixed to the landing catch plate and the stringers are fixable to that tread.
10. An adjustable staircase according to any preceding claim wherein the staircase is d smantleable and reconstructable.
11. A kit of parts for an adjustable staircase according to any preceding claim, I 0 comprising: a plurality of stringer plates; a plurality of joining pieces for assembling the stringer plates into a pair of stringers; a plurality of foot pieces; a plurality of treads; and a landing catch plate.
12. A kit according to claim 11, wherein the stringer plates are of at least two different lengths, and the foot pieces define at least two different angles of rise for the stringers.
13. A method of constructing an adjustable staircase comprising: fixing a landing catch plate to an upper floor level; attaching a pair of stringers to a top tread that is fixed to the landing catch plate; selecting foot pieces and attaching one to the lower end of each stringer to define a desired angle of rise of the stringers and to define the length from a top end of each stringer to a ground engaging portion of each foot piece and fixing a plurality of treads between the stringers, whereby the angle at which the treads are fixed is selected to be substantially horizontal.
14. A method according to claim 13, further comprising assembling each one of the pair of stringers from a plurality of stringer plates connected by joining plates.
15. A method according to claim 13 or 14, wherein the step of fixing a plurality of treads between the stringers comprises fixing the treads in sequence from the bottom of the stringers to the top.