GB2594035A

GB2594035A - Demountable stairs

Info

Publication number: GB2594035A
Application number: GB2001822.2A
Authority: GB
Inventors: Shaw Alan
Original assignee: Regent Engineering Co Walsall Ltd
Current assignee: Regent Engineering Co Walsall Ltd
Priority date: 2020-02-11
Filing date: 2020-02-11
Publication date: 2021-10-20
Anticipated expiration: 2040-02-11
Also published as: GB202001822D0; GB2594035B

Abstract

A modular demountable staircase for installation at a temporary location, the staircase comprises at least two modular step units. Each modular step is formed of two opposing side stringer elements 4, a riser member 6, a tread member 8 and two handrails 20. Each stringer element is characterised in that it is releasably engageable with an end of at least one of the other riser member and the tread members and wherein a stringer element of each modular step unit is releasably engageable with a stringer element of an adjacent modular step. Preferably each modular staircase 10 includes a top step TS, a middle step MS and a bottom step BS. The top step may be fastened to a header assembly 12 attached to a raised floor surface and the bottom step has adjustable base feet 50. The modular steps are configured to enable simple and easy fixing of the parts to each other and to the header assembly 12.

Description

DEMOUNTABLE STAIRS

Field of the Invention.

The present invention relates to demountable stairs for access to temporary floor installations.

Background

The event industry increasingly requires temporary structures such as tents, marquees and staging platforms to be erected with elevated and levelled floors, even where the site may have sloping or uneven ground.

EP2434071B1 of the Applicant discloses their height-adjustable floor support sold under the trade mark FloorStak0 for enabling installation of such structures on uneven ground. The system consists of supporting columns positioned beneath the structure frames of a temporary flooring installation which take the main static and dynamic loadings imposed by the structure. These can be built up quickly and easily in situ and have a positive mechanical connection to the flooring system. The columns can be secured to the ground with stakes or attached to ballast blocks or water filled ballast tanks. The columns consist of four interconnected components including an angle adjustment feature that enable the columns to deal with sloping and uneven ground. Additional intermediate supports are provided at intervals along the flooring beams to give more vertical load resistance to the floor. Telescopic bracing bars are connected to the head and diagonally opposed base of adjacent columns to provide added stability to a structure having an elevation in excess of 60cm.

The FloorStak0 floor support and levelling system has been used to support flooring at a wide variety of events, such as wedding marquees, corporate events and even a wheelchair user demountable spectator platform. These types of temporary structure with elevated and levelled floors are increasing in demand but the provision of a staircase to access the elevated platform poses a problem to the installer. In this respect, the distances from the levelled floor to the ground are often impossible to accurately determine until the structure is in place. Current staircases to access the risen flooring are generally constructed once the structure is installed using 1.

incremental stacks of flooring panels, by building an entirely bespoke staircase for each specific site situation or using a proprietary system of steps and handrails such as those used in the scaffolding industry. Such systems have their fallbacks. Bespoke staircases have better aesthetic appeal which is often important for the event industry, but are costly and time-consuming to construct for a temporary event. Steps used in the scaffolding industry can be installed more quickly for less cost but do not have such an attractive appearance. The Applicant provides a staircase system which has individual steps built up from the raised floor with supports provided beneath each step and a handrail fastened to each end of each step. The assembly of this staircase system is again time consuming for a staircase that may only be required for a few days prior to dismantling and removing the structure from the site.

It is the aim of the present invention to provide a demountable staircase that overcomes, or at least alleviates, the abovemenfioned problems

Summary of the Invention

According to a first aspect of the present invention there is provided a modular demountable staircase comprising at least two modular step units, each modular step unit comprising opposing stringer elements, a riser member and a tread member, wherein each stringer element is releasably engageable with an end of at least one of the riser member and the tread member and wherein a stringer element of each modular step unit is releasably engageable with a stringer element of an adjacent modular step.

The riser member and the tread member may be formed as an integral unit but preferably, the riser member and the tread member are separate components. The riser member is preferably substantially L-shaped in cross-section, each end of the L-shaped member having a tread member receiving channel, preferably extending along the length of the member. More preferably, the tread member receiving channels are diametrically opposed. The tread member is preferably a rectangular member wherein one longitudinal side of the tread member is received in a tread member receiving channel of one riser member and the other longitudinal side is received in a tread member receiving channel of another riser member. Alternatively, each tread member may be provided with riser member receiving channels. In this embodiment, at least one end of the riser member is provided with a lip for receipt within the riser member receiving channel of the tread member.

Each stringer element is preferably provided with a guide track for receiving at least part of the tread member and/or the riser member. For example, parallel upper and lower guide rails may extend from the stringer element to define the guide track. Preferably, the stringer element comprises a main body that forms the general shape of a paralielopipedon having inner and outer parallelogram faces connected by upper and lower walls and rear and front walls. Preferably, a front wall of a stringer element is releasably engageable with rear wall of an adjacent stringer element to provide a sloping profile of the staircase, for example one is provided with a tab on a front wall for receipt within a recess provided in a rear wall of the other. The guide track is preferably provided on an inner face of the stringer element, the guide being at an acute angle to the upper and lower walls whereby, in use, the guide track lies in a horizontal plane.

It is to be appreciated that the complementary tabs and recesses provided on stringer elements of adjacent modular step units are dimensioned such as to provide a snug fit between the parts. More preferably, an annular channel extends from a rear wall of the recess, more preferably being parallel with the guide track. An annular recess is preferably provided in a leading end of the tab for abutment with the end of the annular recess. A fastener, such as a threaded screw, may be inserted through the annular channel and into the annular recess of the tab to provide secure contact between the adjacent stringer elements.

Each stringer element may be provided with a housing block extending upwardly from the guide track, the guide block having at least one socket for receiving a part of a hand rail for the modular staircase. More preferably, the housing block has two spaced apart substantially parallel annular channels for receiving ends of a n-shaped hand rail.

Preferably, the annular channels extend through the housing block and through the upper guide rail. More preferably, each tread member is provided with complementary holes whereby, when inserted into the guide track the handrail is placed through the annular channels and the holes in the tread member to assist in retention of the position of the tread member.

The stringer element is preferably formed as a single piece, for example by injection moulding or 3D printing. However, it is to be appreciated that one or more features of the stringer element may be formed separately and attached to the main body by suitable means.

In a preferred embodiment of the present invention, each modular demountable staircase according to the first aspect of the present invention has three types of stringer element comprising a top step stringer element, a middle step stringer element and a bottom step stringer element. Generally, a single pair of top step stringer elements and a single pair of bottom step stringer elements will be required for a staircase with multiple middle step stringer elements being required depending upon the height of the staircase.

The different types of stringer elements include many common features, including at least one of a tab or recess, a guide track and, optionally, a housing block for receipt of a hand rail. However, the top step stringer elements are only provided with tab or recess on the front wall of the stringer element. Preferably, the rear wall is substantially straight for abutment against a part of a raised flooring structure. More preferably, the rear wall is provided with means for attachment to a part of the raised flooring.

The bottom step stringer element is only provided with a tab or recess on the rear wall of the stringer element. Preferably, the front wall of the stringer element is tapered.

The bottom step stringer element may also be provided with adjustable base feet. Alternatively, adjustable feet may be provided on a bottom step tread member or a bottom step riser member.

It is to be appreciated that in some circumstances no middle step modular unit will be required in which case only a pair of top stringer elements and a pair of bottom step stringer elements may be required, for example for a staircase to a raised flooring of only a low height.

Some or all of the component parts of the modular staircase may be provided with reinforcement to increase the load bearing capacity of the staircase. For example, a reinforced composite material may be provided through some or all of each stringer element. The tabs and recesses may be tapered to increase frictional engagement and/or additional protuberances and recesses may be provided for mating together.

A second aspect of the present invention provides a kit of parts for installation of a modular demountable staircase according to the first aspect of the present invention, the kits of parts comprising: at least two opposing stringer elements, a riser member and a tread member, each stringer element having a guide track for receiving at least part of the tread member and/or the riser member and each tread member being engageable with at least one riser member.

Preferably, each kits of parts includes the components for a top modular step, at least one middle modular step (preferably multiple middle modular steps) and a bottom modular step as hereinbefore described. Preferably, the parts of each type of modular step are essentially the same except for a top step stringer element, a bottom step stringer element and, optionally a bottom step riser member. The kit of parts may also include an appropriate hand rail part, preferably being receivable within the stringer element as hereinbefore described. Suitable fixing means are also provided for securement of the adjacent modular step units.

Brief Description of the Drawinqs

For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings in which: Figure 1 is a perspective view of an assembled modular staircase according to one embodiment of the present invention; Figure 2 is a perspective view of a pair of adjacent stringer units for use in the modular staircase of Figure 1; Figure 3 is a plan view of an inner face of one type of stringer unit shown in Figure 2; Figure 4 is a schematic diagram illustrating attachment of a tread member and handrail to a stringer unit shown in Figure 2; Figure 5 is a schematic diagram illustrating attachment of a pair of tread members to a riser member of the modular staircase shown in Figure 1; Figure 6 is a perspective view illustrating attachment of a modular top step unit of the modular staircase shown in Figure 1 to a header assembly attachable to a raised flooring structure (not shown); and Figure 7 is a part assembled view of the modular staircase shown in Figure 1; shown without handrails but illustrating adjustable base feet.

Detailed Description

The present invention provides a modular demountable staircase system 1 for quick and easy installation at a temporary location.

The modular demountable staircase system comprises a number of modular components that may be assembled together to form a staircase of any required height and width, without additional supporting structures having to be installed below the staircase. The modular staircase may also be installed on uneven or sloping surfaces making it highly convenient for use in the events industry.

An example of the assembled structure is shown in Figure 1 of the accompanying drawings, with Figures 2 to 7 illustrating the various modular components that are assembled together to form the finished staircase. The components make up three types of modular step 10; a top step TS, middle step MS and a bottom step BS as shown in Figure 1 but it is to be appreciated that not all these may be required, such as in the case of a raised flooring structure that is relatively low which may only require the top and bottom modular step units. The top step TS is fastened to a header assembly 12 attached to the raised floor surface (not shown) and the bottom step has adjustable base feet 50. The header assembly 12 comprises a L-shaped plate forming a first and second abutment wall respectively, the top abutment wall having bolt holes 14 with the front abutment wall having protruding studs 16 (see Figure 6).

Each modular step is formed of a number of component parts that are designed to enable simple and easy fixing of the parts to each other and to the header assembly 12 so that the staircase can be installed and removed from the floor surface quickly and easily. Each modular step has two opposing side stringer elements 4, a riser member 6, a tread member 8 and two handrails which are all assembled together as detailed below to form the modular step 10. The only difference between a top step TS, middle step MS and a bottom step BS is the configuration of the stringer element 4t, 4m, 4b, as discussed in further detail below.

While the embodiment shown has separate stringer, riser, tread and handrail components, it is to be appreciated that each modular step may be formed as a two-piece or multiple-piece component for attachment to an adjacent modular step. However, the provision of separate components enables easier packing, transportation and storage of the dismantled staircase.

Referring in particular to Figures 2 and 3, each stringer element is specifically configured to receive complementary parts of the other components of the modular step to allow for easy assembly. In this respect, each stringer element 4 is in the general form of a parallelopipedon having inner and outer parallelogram faces 40 connected by narrow upper and lower walls 41a, 41b and rear and front walls 41c, 41d. Each inner face 42 of each stringer element has a pair of substantially parallel guide rails 47u, 471 extending at least partially across the element defining a track 47. The rails extend at an acute angle to the upper or lower sides walls 41a, 41b so that, once assembled, the track 47 between each pair of rails lies substantially on the horizontal plane (see, in particular, Figure 3).

At least one of the front or rear wall 41d, 41c of each stringer element has a recess 45 or a tab 43, depending upon whether the stringer element is for a top step, middle step or bottom step. In the case of a stringer element 4t for a top modular step, the intended rear wall 41c is straight and provided with a pair of longitudinally spaced apart slots extending into circular holes or recesses 46. The intended front wall 41d is provided with a recess 45, seen in detail in Figure 3. In the case of a middle modular step MS, the rear wall 41c is provided with a tab 43 and its opposing front wall is provided with a recess 45 (as shown in Figure 2). However, the arrangement may be inversed, with the tabs provided in the front walls with complementary recesses provided in the rear walls of the stringer elements. The stringer element for the bottom step BS is provided with a tab 45 extending from its rear wall only, as seen in Figure 1, with the lower wall 41b of the bottom step tapering towards the upper wall 41a to provide a very narrow front wall 41d. Additionally, an annular channel 45b extends from an outer wall of the stringer element to the inside wall of the recess 45.

The configuration of the tabs 43, recesses 45, annular channels 45b and guide rails 47u, 471 provided on the stringer element is such as to enable the correct alignment and fixing of the stringer element to the riser and tread members 6, 8. The upper and lower inner walls 45a of the recess are parallel with the guide rails, as seen in Figure 3. Additionally, the lower wall 41b is provided with an indent which also has an upper wall parallel with the guide rails and lying in the same plane as the upper inner wall 45a of the recess. The complementary tab 43 of an adjacent stringer element has walls that extend from the rear wall, the tab walls being parallel with the guide rails and upper and lower walls of the recess and being dimensioned to be substantially the same volume as the recess 45. The tab 43 also has an annular recess 43a provided in the end wall thereof.

A housing block 42 also extends upwardly from the upper guide rail 47u, the block having a sloping upper wall that matches the contours of the upper wall 41a of the stringer element, the housing block having two substantially parallel annular channels 42a that extend entirely through the housing block from the upper wall downwardly into and through the upper guide rail 47u (see, in particular, Figure 4).

Each stringer element is preferably made of a single piece of material, such as by moulding or using a three-dimensional printer. However, one or more parts may be made separately and fixedly secured to the rest of the stringer element by suitable means.

A handrail 20, tread member 8 and riser member 6 for each modular step are shown in further detail in Figures 4 and 5. Note that the opposing ends of the tread and riser members in Figure 4 would be provided with a second stringer element and handrail but these have been omitted for simplicity. The riser member is a one-piece unit having a main riser section 64 with two receiving channels 62 and 66, the openings of the respective channels being diametrically opposed. In the illustrated embodiment, the riser section 64 is in the preferred shape of a rectangle, the height of which dictates the height of the modular step but other shapes could be used, such as a square. The intended upper edge of the riser section is provided with a substantially U-shaped section along the length of the upper edge to form the upper receiving channel 62, wherein the riser section turns inwardly at substantially 90 degrees, then turns through 90 degrees to from a small lip parallel with the riser section before turning outwardly at substantially 90 degrees to define the channel 62. The opposing lower edge of the riser section is provided with substantially S-shaped section along the length thereof for providing the lower receiving channel 66, with the channel opening in the opposing direction to the upper receiving channel 62. Again, the S-shaped section is made by providing a series of turns through 90 degrees of the lower edge of the riser section.

Each tread member 8 comprises a rectangular sheet of material having a pair of axially aligned holes 82 at each end of the sheet. The sheet of material is of a width w substantially the same as the length of the track 47 provided in each stringer element and of a depth substantially the same as the spacing between the upper and lower guide rails and the depth of the upper and lower receiving channels of the riser elements. The length I of the tread member is the same as the length of the upper and lower receiving channels of the riser element. However, it is to be appreciated that the tread member and riser elements may be provided in any desired length. For example, the tread and riser members may be provided in sets of particular lengths to provide staircases having different sized stairs. The tread and riser members may also be provided as an integral unit provided in different lengths. This would again make storage and transportation more difficult but would aid assembly and disassembly of the staircase.

The handrail 20 for providing a banister along each side of the staircase is a substantially elongated n-shaped member made from cylindrical tubing having a diameter substantially the same as the diameter of the annular channels 42a of the housing block 42 of the stringer element 4 and the holes 82 of the tread member 8.

In the illustrated embodiment, the modular bottom step BS has a riser element provided with adjustable base feet 50 extendable from the underside of its lower edge (see Figure 7) . For example, the adjustable feet may comprise a pair of legs 52 pivotally mounted to the riser element at pivot 54 and having connecting arms 53 pivotally mounted to the legs at pivot point 56. The arms 53 are slidably mounted with respect to the underside of the riser element and are movable by means of lever 58 at each end thereof. The lever also includes locking means, such as a threaded pin, to lock the arm at a desired position, thereby locking the legs at a desired height. The pair of legs are each independently adjustable by means of their own arm and lever mechanism to take account of uneven ground.

The assembly of a modular staircase using the component parts discussed above will now be described. It will be appreciated that the component parts may be put together in a different sequence to this example. Firstly, the header assembly 12 comprising a L-shaped plate is fixed to the raised flooring structure via bolt holes 14 at a position where a demountable staircase is required. A top modular step unit TS is then assembled by placing a tread member 8 in the upper receiving channel 62 of a riser member (Arrow D in Figure 4) and then placing a top step stringer element 4t at each end of the tread and riser. In this respect, the opposing ends of the tread member slot into the tracks 47 defined by the guide rails 47u, 471 of each springer element (see arrow A in Figure 4) and a handrail 20 is then placed through the annular channels 42a of the housing block 42 of each stringer element 4 and the holes 82 of the tread member 8 to provide a relatively secure top step unit TS (see Figure 6). The straight rear wall 41c of the stringer element is then placed against the header assembly 12 such that circular holes 46 receive the protruding studs 16 of the front abutment wall. The step is then moved downwardly causing the studs to slide into the longitudinally spaced apart slots thereby securing the top modular step to the header assembly.

A first middle modular step unit MS is then constructed in a similar manner to the top step TS. Another tread member 8 is placed in an upper receiving channel 62 of another riser member (Arrow D in Figure 4) and then a middle step stringer element 4m (see Figure 2) is placed at each end of the tread and riser members. The opposing ends of the tread member slot into the tracks 47 defined by the guide rails 47u, 471 of each springer element (see arrow A in Figure 4) and a handrail 20 is then placed through the annular channels 42a of the housing block 42 of each stringer element 4m and the holes 82 of the tread member 8 to provide a relatively secure middle step unit MS. The unit is then brought into contact with the assembled top step TS with the rear tab 43 of each stringer element 4m of the middle step being received within the recess 45 of the front wall 41d of each stringer element 4t of the top modular step and the tread member 8 of the middle step is received within the lower receiving channel 66 of the riser element of the top step TS. In assembling these components together, the annular channel 45b that extends from an outer wall of the top step stringer element 4t to the inside wall of the recess 45 lines up with the tab 43 and annular recess 43a of the middle step stringer element 4m to enable a threaded screw 48 to be inserted through the annular channel 45b and received within the annular recess 43a, thereby further securing the middle step MS to the top step TS.

Any required number of identical middle steps may then be attached to the first middle step to built up the required height of the staircase. As discussed above, all component parts are the same except that each middle step has middle stringer elements 4m, wherein a tab 43 of one stringer element 4m is received within a recess 45 of an adjacent stringer element 4m and secured together by a threaded screw 48.

A bottom modular step BS is then attached to the lowermost middle step MS when the distance between the lowermost step and the ground is approximating the height of a middle modular step. Again all components are the same except that a pair of bottom stringer elements 4b are used having a tab 45 extending from its rear wall 41c only for receipt within the recess of the front wall 41d of the adjacent middle step. The lower wall of the bottom step tapers towards the upper wall to provide a very narrow front wall 41d. Again, a threaded screw 48 is placed through an annular channel 45b that extends from an outer wall of the stringer element to mate with the tab 43 of the adjacent stringer element. It is to be appreciated that all of the threaded screws may be placed through the annular channels of the stringer elements of all the modular steps once all the steps have been assembled, if preferred. However, it has been found that fastening each one in turn prior to attachment of the next modular step provides for easier assembly.

Additionally, the bottom step riser member is provided with adjustable base feet 50. Each arm 53 is slid along the riser element using lever 58 to extend each leg 52 outwardly from the underside of the riser element until their ends contact the floor (see arrow E in Figure 7). Once in the desired position, a threaded pin (not shown) locks each arm in position thereby securing each leg at the required height.

The modular component parts enable a demountable staircase of any required height and width to be assembled and dismantled quickly and easily. Furthermore, the finishing of the various parts may be smooth and aesthetically pleasing. The attachment of all the parts is such that the conjoined stringer elements appear to provide a continuous staircase having a closed backing stringer.

The attachment of the modular stringer elements as hereinbefore described adds to the strength of the staircase, with these being the main loading bearing parts of the staircase. As such these elements may also be reinforced, for example, a reinforced composite material provided through some or all of the stringer element. The base of the balustrade members may also be such as to capture the riser elements in addition to the tread member. Additional means may also be provided for aiding satisfactory securement of the component parts. For example, further complementary tabs and recesses may be provided on mating parts of the components, such as an additional protuberance extending from an inner wall of the recess 45 for mating with another recess provided at a corresponding location on the tab 43. The parts may also be tapered to provide additional securement by frictional means.

The banister shown in the illustrated example provides separate handrails for each modular step. This has the added benefit that long continuous pieces of material are not required which make storage and transportation more difficult. However, it is to be appreciated that the design may be altered to provide a continuous handrail, for example wherein two poles extend upwardly from each stringer element and then a single rod is attachable to all the poles. Alternatively or additionally, side parts may be provided for forming a closed balustrade The construction of other component parts may also vary to provide different designs of staircase, such as the main section of each riser element being relieved of material to provide a more open staircase.

The modular staircase is preferably provided as a kit of parts. A customised kit of parts may be provided for assembling a demountable staircase of a given height and width.

Claims

CLAIMS: 1. A modular demountable staircase comprising at least two modular step units, each modular step unit comprising opposing stringer elements, a riser member and a tread member, wherein each stringer element is releasably engageable with an end of at least one of the riser member and the tread member and wherein a stringer element of each modular step unit is releasably engageable with a stringer element of an adjacent modular step.
2. The modular demountable staircase as claimed in claim 1, wherein the riser member is substantially L-shaped in cross-section, each end of the L-shaped member having a tread member receiving channel, preferably extending along the length of the member.
3. The modular demountable staircase as claimed in claim 2, wherein the tread member receiving channels are diametrically opposed.
4. The modular demountable staircase as claimed in claim 2 or claim 3, wherein the tread member is a rectangular member wherein one longitudinal side of the tread member is received in a tread member receiving channel of one riser member and C\I the other longitudinal side is received in a tread member receiving channel of another riser member.
5. The modular demountable staircase as claimed in any one of the preceding claims C\I wherein each tread member is provided with riser member receiving channels.
6. The modular demountable staircase as claimed in claim 5, wherein at least one end of the riser member is provided with a lip for receipt within the riser member receiving channel of the tread member.
7. The modular demountable staircase as claimed in any one of the preceding claims wherein each stringer element is provided with a guide track for receiving at least part of the tread member and/or the riser member, preferably comprising parallel upper and lower guide rails extending from the stringer element to define the guide track.
8. The modular demountable staircase as claimed in claim 7, wherein the stringer element comprises a main body that forms the general shape of a paralielopipedon having inner and outer parallelogram faces connected by upper and lower walls and rear and front walls, a front wall of a stringer element being releasably engageable with a rear wall of an adjacent stringer element to provide a sloping profile of the staircase.
9. The modular demountable staircase as claimed in 8 wherein the guide track is provided on an inner face of the stringer element, the guide being track at an acute angle to the upper and lower walls whereby, in use, the guide track lies in a horizontal plane.
The modular demountable staircase as claimed in claim 8 or claim 9 wherein complementary tabs and recesses are provided on stringer elements of adjacent modular step units for engagement with complementary tabs and recesses of adjacent stringer elements, preferably wherein an annular channel extends from a rear wall of the recess, more preferably wherein an annular recess is provided in a leading end of the tab for abutment with the end of the annular recess and a fastener, is receivable i through the annular channel and into the annular recess of the tab to provide secure contact between the adjacent stringer elements.
11. The modular demountable staircase as claimed in claim 10 when dependent from any one of claims 7 to 9 wherein the annular channel is parallel with the guide track.
12. The modular demountable staircase as claimed in any one of the preceding claims wherein each stringer element is provided with a housing block, the housing block having at least one socket for receiving a part of a hand rail for the modular staircase.
13. The modular demountable staircase as claimed in claim 12 when dependent from any one of claims 7 to 11 wherein the housing block extends upwardly from the guide C\I track.
("III 14. The modular demountable staircase as claimed in claim 13 wherein the housing block has two spaced apart substantially parallel annular channels for receiving ends C\I of a n-shaped hand rail, the annular channels extending through the housing block O and through the upper guide rail of the guide track.
15. The modular demountable staircase as claimed in claim 14, wherein each tread member is provided with complementary holes whereby, when the tread members are inserted into the guide track, the handrail is placed through the annular channels and the holes in the tread member to assist in retention of the position of the tread member.
16. The modular demountable staircase as claimed in any one of the preceding claims having three types of stringer element comprising a top step stringer element, a middle step stringer element and a bottom step stringer element.
17. The modular demountable staircase as claimed in claim 16 wherein each type of stringer element includes at least one of a tab or recess, a guide track and, optionally, a housing block for receipt of a hand rail and wherein the top step stringer element has only a tab or recess on the front wall of the stringer element, the rear wall being substantially straight for abutment against a part of a raised flooring structure.
18. The modular demountable staircase as claimed in claim 16 or claim 17 wherein the bottom step stringer element is only provided with a tab or recess on the rear wall of the stringer element and the front wall of the stringer element is tapered.
19. The modular demountable staircase as claimed in claim 16, 17 or 18 wherein the bottom step stringer element is provided with adjustable base feet.
20. The modular demountable staircase as claimed in claim 16, 17 or 18 wherein adjustable feet are provided on a bottom step tread member or a bottom step riser member.
21. A kit of parts for installation of a modular demountable staircase according to any one of claims 1 to 20, the kits of parts comprising: at least two opposing stringer elements, a riser member and a tread member, each stringer element having a guide track for receiving at least part of the tread member and/or the riser member and each tread member being engageable with at least one riser member.
22. The kit of parts as claimed in claim 21 wherein the kit includes components for a top O modular step, at least one middle modular step (preferably multiple middle modular 0.1 steps) and a bottom modular step
23. The kit of parts as claimed in claim 21 or claim 22 further comprising a hand rail part, preferably being receivable within the stringer element, and suitable fixing means for securement of adjacent modular step units.