Field of the Invention

This invention relates to a set of stairs and in particular to use of a set of stairs temporarily in a construction site, but not limited to such use. Although the invention can be applied to a range of uses, for convenience sake it shall be described herein in terms of a set of stairs for temporary use in a construction site.

Background to the Invention

Generally in construction places, and particularly in construction of domestic homes, the construction can have two or more storeys. A range of trades people must continuously enter the building and need to proceed to the upper storeys. This includes builders, plasterers, electricians, plumbers, painters etc. Each will have materials, products and/or equipment that must be transported to the upper storeys. However there are also a range of other people from architects, interior designers, current owners, prospective owners, bankers etc., who need to see a site while under construction, so as to be able to undertake their reviews and professional services.

Although the building will be designed to have permanent staircases installed, the installation of the staircase is often the last fitted constructional element. This can be due to the staircase being purpose built offsite, or to try and protect the staircase from damage from other constructional activities, or to the need to have other constructional activities completed before attaching the staircase. In the meantime, instead of a final staircase there is an empty well chamber into which the staircase will be installed. In order to facilitate the access to the upper storeys, there is usually a ladder located in the well chamber and attached to the upper storey and often locked in position. An alternative location for a ladder could be in external or internal scaffolding.

Clearly the problems with a ladder is that it is very awkward to use when carrying materials including plasterboards or plumbing elements or paint or when carrying tools or ladders or other equipment needed for the activity in the upper storey. Due to the carrying limitation of the trades people, there is often a build-up of materials and tools at the bottom of the ladder or at the top of the ladder as each of the trades people tries to ferry material and tools in batches between the storeys. This creates a hazard which that trades person needs to avoid tripping on and falling down the stairwell. Other trades people working in the same confined space and with the same confined access between storeys are also at risk.

There is a real danger in construction sites due to this problem and a real occupational health and safety issue applies. Summary of the Invention

Accordingly, it is an object of the present invention to overcome or at least ameliorate at least one of the disadvantages of the prior art or to at least provide an effective alternative.

The present invention provides a set of stairs including a pair of stringers, and a plurality of treads; wherein the treads are removably attachable to the stringers.

The stringers are preferably substantially linear with at least partially enclosed areas for receiving and connecting the treads and a hand rail, wherein in a dismantled form the stringers and treads are substantially free of protrusions and thereby provide readily transportability without damage and in use the connected stringers and treads are substantially free of protrusions and thereby are safe.

The interengaging connection means tend the treads to a captured position until a releasable connection means is actively released. The interengaging connection means can include a protrusion means extendable from the stringer or tread and a receiving formation on the tread or stringer forming a captured position until a releasable connection means is actively released. The interengaging connection means tend the protrusion means extendable from the stringer or tread to a captured position by a resilient spring means until a releasable connection means is actively released and retracted against the spring.

Each of the treads include a box-like structure can have an interengaging connection means mounted therein for interlocking with the stringers to provide a demountable tread on the stairs. The treads have a box-like structure having the interengaging connection means in one form of retractable protruding means mounted within the box-like structure with the retractable protruding means able to interlock with the stringers to provide a demountable tread on the stairs. The stringers can have a consistent squared U-shaped cross section with openings to receive hand rail on one side and openings to receive a locking stair engagement means on the other.

The invention also provides a method of providing temporary stairs including the steps of: a) Providing a fixing means b) Attaching the fixing means at a height determined relative to a floor c) Providing a pair of stringers d) Attaching a relative top end of each stringer to a lateral end of the fixing means at spaced parallel location to each other such that they extend outwardly down to the floor e) Providing a plurality of demountable treads each having an interengaging connection means f) Attaching the plurality of treads between the stringers Wherein a demountable stair is provided that can be readily demounted to individual portable parts.

Preferably the stringers are substantially linear with at least partially enclosed areas for receiving and connecting the treads and a hand rail, wherein in a dismantled form the stringers and treads are substantially free of protrusions and thereby provide readily transportability without damage.

The stringers can have a consistent squared U-shaped cross section with openings to receive hand rail on one side and openings to receive a locking stair engagement means on the other. The treads can include a box-like structure having an interengaging connection means mounted therein with retractable protruding means for interlocking with the stringers to provide a demountable tread on the stairs.

The invention in one form provides a set of stairs including a pair of stringers, a plurality of treads and releasable connection means for fitting and holding the plurality of treads therebetween, wherein the treads are removably attachable to the stringers; the stringers being substantially linear with a consistent squared U-shaped cross section too form at least partially enclosed cross- sectional areas for receiving and connecting the treads, and for receiving and connecting a hand rail; the treads including a box-like structure having an interengaging connection means mounted therein with two retractable protruding means on each opposing end of each of the treads for interlocking with the stringers to provide a demountable tread on the stairs; one or more releasable connection means holding the treads in a captured manner until the releasable connection means are actively released, the interengaging connection means tending each of the protrusion means extendable from the stringer or tread to a captured position by a resilient spring means until a releasable connection means is actively released and retracted against the spring; a locking engagement means comprising an elongated lock plate having spaced holes, and a locking means such as a padlock wherein the protrusion means of the releasable connection means extend from each relative of the treads and through receiving holes of the stringers and receiving holes in the lock plate when positioned within the cavity of the stringers and the padlock engaging through hole in end of one protrusion to receive the padlock and prevent retraction of the protrusion from the stringer; and fixing means connecting to relative top ends of the stringers for fixing at a height determined relative to a floor attaching a relative top end of each stringer to a lateral end of the fixing means at spaced parallel location to each other such that they extend outwardly down to the floor, wherein in a dismantled form the stringers and treads are substantially free of protrusions and thereby provide readily transportable without damage. Also the invention provides a kit forming a set of stairs comprising the separate elements of a set of stringers substantially linear with a consistent squared U- shaped cross section to form at least partially enclosed cross-sectional areas for receiving and connecting the treads, and for receiving and connecting a hand rail; and a plurality of treads each including a box-like structure having an interengaging connection means with retractable protruding means mounted therein for interlocking with the stringers to provide a demountable tread on the stairs; wherein the kit forming a set of stairs is readily transportable and substantially free of protrusions and thereby are safe.

Brief Description of the Drawings In order that the invention can be more readily understood one or more embodiments of the invention are further described by way of example only with reference to the accompanying drawings wherein:

Figure 1 is a diagrammatic side view of a set of stairs in accordance with the invention connecting between a first floor A and a second floor B of a multi storey building having an upright wall C;

Figure 2 is a diagrammatic front view of the set of stairs of Figure 1 ;

Figure 3 is a diagrammatic angled overhead view of the set of stairs of Figure 1 ; Figure 4 is a diagrammatic cross sectional detail of one stringer and a tread of the set of stairs of Figure 1 , taken on a line 4 - 4 in Figure 1 , but including hand rail;

Figure 5 is a diagrammatic angled overhead view of one pair of spaced apart stringers of the set of stairs of Figure 1 showing the receiving handrail holes in an upper surface of the U shaped cross sectional stringer;

Figure 6 is a diagrammatic side view of one stringer of the set of stairs of Figure 1 showing the receiving holes of locking stair engagement means of the treads in a side surface of the U shaped cross sectional stringer; Figure 7 is an overhead view of one tread of the set of stairs of Figure 1 with protruding locking stair engagement means;

Figures 8 and 9 are front views of the box like treads of Figure 7 of the set of stairs of Figure 1 with protruding and non protruding locking stair engagement means respectively; Figure 10 is an underneath view of the open bottom box like one tread of Figure 7 of the set of stairs of Figure 1 with locking stair engagement means in protruding position;

Figure 11 is a side view showing a schematic representation of a locking stair engagement means of a tread used in the set of stairs of Figure 1 ; Figure 12 is a side view showing in perspective a schematic representation of the set of stairs of Figure 1 which has been assembled; and

Figure 13 is a side view showing in perspective a schematic representation on an enlarged scale a portion of the assembled set of stairs of Figure 12.

Description of illustrated Embodiment of the Invention Referring to the accompanying representations, Figures 1 and 2 show a diagrammatic side view of a set of stairs 10 according to the invention. The set of stairs is constructed using a pair of stringers 12 which are spaced apart - -

relative to each other to accommodate a plurality of treads 14 at spaced apart, predetermined positions in between the stringers. In the illustrated example, the set of stairs is used between a first floor A and a second floor B of a multi storey building having an upright wall C. Referring in particular to Figure 2, a fixing means 16A is used to secure an upper end 18 of the set of stairs 10 to the upright wall C at a height determined relative to the floor A. A top end 20 each stringer 12 is secured to a lateral end 22 of the fixing means such that they extend outwardly down to the floor A. This allows the wall C to provide an anchoring point through the fixing means to the set of stairs.

In order to improve stability of the set of stairs 10, a second fixing means 16B may be secured to the first floor A so that each end of the set of stairs is secured to structure.

Referring to Figure 3, the plurality of treads 14 are aligned relative to each other along a length of the pair of stringers so that the treads are substantially parallel to each other.

The stringers have at least partially enclosed cross-sectional areas for receiving and connecting the treads, wherein in a dismantled form the stringers and treads are substantially free of protrusions and thereby are readily transportability without damage and in use the connected stringers and treads are substantially free of protrusions and thereby are readily safe.

Figure 4 shows a cross-sectional side view through one of the stringers 12 to show fitment of the treads 14 to the stringers. Additionally, Figures 5 and 6 show top and side openings 26 and 28 which are formed on a respective side of the stringer. The stringer has a consistent squared U-shape with the top and side openings 26 and 28 respectively positioned to receive a handrail 30 on the top side and a locking stair engagement means or inter-engaging connection means 32 on the side. The inter-engaging connection means is carried by the treads 14 and allow the treads to be removably attached to the stringers 12. It should note that the orientation of the U-shape may be altered to requirement. For example, the top section may be longer than the respective side sections. In order to allow for enough room to mount the treads 14, the U- shape therefore may be rotated by 90° clock wise to allow for the treads to be secured to the top section, now the side section, and the hand rail to be secured to the side section which is now positioned at the top.

In the version shown in Figures 1 to 10, the inter-engaging connection means 32 includes one retractable protruding means 40 which engages with a respective side opening 26. The tread may be tubular shaped thereby required only one retractable protruding means 40 for attachment to the stringers 12. The pair of stringers may be formed with formation which extends into the stringer and which is designed to receive a respective end of the tread. This formation will reduce the likelihood of the tread turning about the retractable protruding means 40 when a load is placed on the tread. The plurality of treads 14 are shown in greater detail in Figures 7 to 10. Each of the plurality of treads has a box-like structure 36 to which the inter-engaging connection means 32 is mounted on an underside. The inter-engaging connection means includes a retractable protruding means 40 which is designed for interlocking with the side openings 28 of the stringers 12 to provide a demountable tread on the set of stairs 10.

The stringers 12 are substantially linear with at least partially enclosed areas 36 for receiving and connecting the treads 14 and the hand rail 30. In a dismantled form the stringers and treads are substantially free of protrusions and thereby provide readily transportability without damage as is shown respectively in Figures 6 to 9.

The retractable protruding means 40 includes a biasing member 42 which biases the retractable protruding means to an extended position 44 shown in Figures 7, 8 and 10. Each tread 14 further includes a lock means or member 46 which retains the retractable protruding means 40 in a retracted position 48 showing Figure 9. An example of a tread 14 is shown in Figure 11. The box-like structure 38 of the tread carries on an underside thereof the inter-engaging connection means 32. In the illustrated example the inter-engaging connection means includes two retractable protruding means 40 each of which is biased by the biasing member 42 to the extended position 44. A lock pin 50 is carried by each retractable protruding means for engagement with the lock member 46. Engagement of the lock pin 50 with a free end 52 of the lock member allows the retractable protruding means to be secured in the retracted position 48. Thus, once the lock pin is supported by the free end 52, the retractable protruding means 40 is kept in the retracted position against the biasing force of the biasing member 42 thereby to allow the tread 14 to be substantially free of protrusions.

The box-like structure 38 may include suitable knurling or a pattern of protrusions which reduces the likelihood of slippage on the tread. Figure 12 shows the set of stairs 10 in an assembled form. In the illustrated example the set of stairs is assembled using the steps of securing the fixing means 16 at a predetermined position on the wall C so that the upper end 18 of the set of stairs 10 is in proximity to the second floor B. Typically the fixing means 16 will be secured at a determined height which will allow a user of the set of stairs to readily climb onto the second floor B from the uppermost tread 58. The pair of stringers 12 will be supported at their respective top ends 20 by the fixing means 16. Support of the pair of stringers 12 by the fixing means is achieved by attaching the respective top end 20 of each stringer 12 to a lateral end 22 of the fixing means 16 at spaced parallel location to each other such that they extend outwardly down to the floor. The plurality of demountable treads 14, each having an inter-engaging connection means 32, are secured relative to the pair of stringers 12. The plurality of treads 14 are attached between the pair of stringers 12 using the inter-engaging connection means 32.

The handrail 30 is thereafter secured to the pair of stringers 12 using the top openings 26. In the illustrated embodiment of Figures 11 to 13 the pair of stringers 12 has a consistent squared U-shape. This allows a number of - - spaced apart, spigot formations 60 to be positioned inside the tubular stringer for engagement with one end of a respective vertical member 62 of the handrail. The spigot formations include a crosspiece 63 which is secured at opposed ends to a respective side section of the stringer so that the spigot formation is mountable inside the U-shaped. An upper, horizontal member 64 of the handrail includes a number of spigot blocks 66 which allow an upper end of the vertical member 62 to be secured in relation to the upper, horizontal member 64.

Each of the vertical members 62 are anchored against substantial vertical movement. The bottom end of the vertical member is engaged with a respective spigot formation 60 with a portion 68 of the vertical member being supported by the top side of the respective stringer 12 surrounding the top opening 26. This allows each of the vertical members 62 to be inserted through a respective top opening 26 until an end of the vertical member is registered with the respective spigot formation 60. The vertical member is thus substantially locked against pivotal movement relative to the stringer.

In one example, the spigot blocks 66 are registered with the upper, horizontal member 64 using spaced apart formations 68. The formations are designed to allow for removal of the spigot blocks so that, once removed, the horizontal member has a substantial smooth outer profile.

Referring in particular to Figure 13, the side openings 28 extend through one side section of the pair of stringers 12. This allows free ends 72 of the retractable protruding means 40 to extend into the U-shape of the stringer. A lock plate 74 is fitted over the projecting free ends. Padlocks 76 are secured to free ends by fitment through engagement of lock shanks with a respective hole formed through the free ends inside the stringers. This allows the plurality of treads 14 to be secured to the pair of stringers to secure the set of stairs 10. Such securing reduces the likelihood of unauthorised disassembly of the set of stairs 10 or the stringers moving out of parallel positioning relative to each other due to use which could cause one or more of the treads falling out of the set of stairs. The invention could therefore provide a set of stairs which allow in a dismantled form the stringers and treads to be substantially free of protrusions and thereby provide readily transportability without damage.

While we have described herein a particular embodiment of a stairs, it is further envisaged that other embodiments of the invention could exhibit any number and combination of any one of the features previously described. However, it is to be understood that any variations and modifications which can be made without departing from the spirit and scope thereof are included within the scope of this invention.