GB2592349A

GB2592349A - Cantilever platform

Info

Publication number: GB2592349A
Application number: GB2001315.7A
Authority: GB
Inventors: Robert Pledger Shaun; Duncan McEwan Timothy; Clarkson Craig
Original assignee: Flexi Group UK Ltd
Current assignee: Flexi Group UK Ltd
Priority date: 2020-01-30
Filing date: 2020-01-30
Publication date: 2021-09-01
Anticipated expiration: 2040-01-30
Also published as: GB202001315D0; GB2592349B; GB2592349A9

Abstract

A cantilever platform, such as a balcony provides a firebreak preventing fire transmission from one side of the platform to the other and so preventing fire spread between storeys on the outside of a multi-storey building. The platform, is arranged in use to connect to a support structure and to extend laterally outward therefrom, the platform comprising a barrier spanning an area parallel to the lateral extension of the platform, at least a portion of the barrier being non-combustible, the barrier being arranged in use to prevent fire transmission between opposing sides of the barrier. The barriere may be a layer of foamed concrete or a cementitious panel. An intumescent sealing strip may be provided between the platform and the building structure.

Description

CANTILEVER PLATFORM FIELD OF THE INVENTION

The present invention relates to cantilever platforms, such as cantilever balconies, that provide fire protection.

BACKGROUND

Elevated platforms are used for a number of purposes. There are a number of forms of elevated platforms, such as stages, gantries, catwalks or balconies. These platforms can be supported by various means. One such support means is via a cantilever mechanism.

A cantilever platform is typically a rigid structural element that is attached at one end to a support structure, such as a wall, from which it protrudes. This attachment allows any load applied to the platform to transfer through the platform to the support structure by a rotation moment and shear stress at the attachment point.

Regulations in many countries require new homes to include outside space for all dwellings. For high-rise buildings, this means that some form of balcony is needed to provide the outside space.

Cantilever balconies are commonly used to provide the outside space for high-rise buildings. This is because the cantilever nature allows only the core structure of the building to be used to provide support for the balcony. Further this means the building footprint is not expanded by the addition of the required outside space.

Since the disaster at Grenfell Tower in London with fire spreading throughout the building, consideration given to fire safety in high-rise buildings has increased.

One part of this consideration is how to reduce the spread of fire on the outside of the building. There is therefore a need to improve the fire performance of the exteriors of buildings.

This need to improve fire performance must be balanced against the requirement to provide outside space. This is typically achieved by balconies being fabricated so they do not burn in a fire. This only results in balconies having a neutral effect on the fire performance, since they neither contribute to a fire nor prevent its spread. In view of balconies already being made from materials that do not burn, turning the neutral effect into a positive effect so as to help prevent fire spread presents a significant difficulty. However, there are also limitations on the further advances that can be made to fire performance of other aspects of the outside of a building, such as cladding. The issue of how to improve fire performance of the outside of a high-rise building therefore needs to be addressed.

SUMMARY OF INVENTION

According to a first aspect, there is provided a cantilever platform for (i.e. suitable for) providing a firebreak, the platform being arranged in use to connect to a support structure and to extend laterally outward therefrom, the platform comprising a barrier spanning an area parallel to the lateral extension of the platform, at least a portion of the barrier being non-combustible, the barrier being arranged in use to prevent fire transmission between opposing sides of the barrier.

This provides insulation and prevention of the spread of fire past the platform. The result of this is that passive fire protection is provided reducing the need for any sprinkler or other fire suppression system to be used while improving the fire performance of the platform. This means the platform has a positive effect on the fire performance of any building or structure to which it is mounted.

Therefore, due to the non-combustible nature of at least a portion of the barrier, fire transmission is thereby reduced or prevented.

The platform may be a stage, balcony, staircase or walkway. Regardless of the form of the platform, the barrier may be arranged horizontally or at any angle as long as it spans the area, whether in the plane of the area or at an incline to the area.

The support structure may be a building, wall, frame or other form of man-made or natural object or landform.

The phrase "non-combustible" is intended to mean not able to catch fire or burn.

Typically the at least a portion of the barrier that is non-combustible may be fire resistant (i.e. prevent transmission of fire across the barrier) for one hour or for two hours, such as by having a fire rating of Euroclass A2 or Euroclass Al respectively.

Euroclass Al fire rating means that, for homogeneous products, the product has a gross calorific potential (PCS) of no more than 2.0 MegaJoules (MJ) per Kilogram (kg), as defined by EN ISO 1716, and undergoes a temperature rise of no more than 30 degrees centigrade (°C), has mass loss of no more than 50%, and has a duration of sustained flaming of zero (0) seconds (s) (i.e. no sustained flaming), as defined by EN ISO 1182, under testing. For non-homogeneous products that are a substantial component these criteria are the same as for homogeneous products, but for non-homogeneous products that are an external non-substantial component either the PCS must be no more than 2.0 MJ/kg (again as defined by EN ISO 1716) or no more than 2.0 MJ per square metre (m2), as defined by EN ISO 1716, and, as defined by EN 13823, have a fire growth rate index (FIGRA) of no more than 20 Watts (W) per s, a lateral flame spread (LFS) of less than the edge of the component, a total heat release of no more than 4.0 MJ and satisfy the conditions of classifications Si and dO. For an internal non-homogeneous, non-substantial component, as defined in EN ISO 1716, the PCS must be no more than 1.4 MJ/m2, and for the non-homogeneous product, as defined in EN ISO 1716, as a whole the PCS must be no more than 2.0 MJ/kg.

Euroclass A2 fire rating means that for the product as a whole, as defined by EN 13823, the FIGRA must be no more than 20 W/s, have a THR of no more than 7.5 MJ and have an LFS of less than the edge of the product. For a homogeneous product, the PCS must be no more than 3.0 MJ/kg, as defined by EN ISO 1716, or the temperature rise must be no more than 50 °C, the mass loss must be no more than 50% and the duration of sustained flaming must be no more than 20 s, as defined by EN ISO 1182. For non-homogeneous products, as defined in EN ISO 1716, for substantial components, the requirements are the same as for homogeneous products; for internal and external non-substantial components, the PCS must be no more than 4.0 MJ/m2; and for the product as a whole, the PCS must be no more than 3.0 MJ/kg.

Each of Euroclass Al and A2 has variations depending on the type of product.

For example, floorings, linear pipe thermal insulation products, and electric cables have different requirements. The variations to the above criteria can be found in the relevant regulations (EN 13823, EN ISO 1716 and EN ISO 1182). The various tests used to carry out assessments of products that are detailed in the regulations are set out below.

The Single Burning Item (SBI) test of EN 13823 is based on a fire scenario of a single burning item, e.g. a wastebasket, located in a corner between two walls covered with the lining material to be tested. The SBI test specimens are installed on a specimen holder with two vertical wings made of non-combustible board. The specimen holder wings of sizes 1.0 metres (m) by 1.5 m and 0.5 m by 1.5 m form a right-angled corner configuration. The thermal exposure on the surface of the specimen is produced by a right-angled triangle-shaped propane gas burner placed at the bottom corner formed by the specimen wings. The heat output of the burner is 30 kW resulting in a maximum heat exposure of about 40 kiloWatts (kW per m2 on an area of approximately 300 square centimetres (cm2). The burner simulates a single burning item. Combustion gases generated during a test are collected by a hood and drawn to an exhaust duct equipped with sensors to measure the temperature, light attenuation, 02 and CO2 mole fractions and flow-induced pressure difference in the duct. The performance of the specimen is evaluated for an exposure period of 20 minutes.

During the test, the heat release rate (HRR) is measured by using oxygen consumption calorimetry. The smoke production rate (SPR) is measured in the exhaust duct based on the attenuation of light. Falling of flaming droplets or particles is visually observed during the first 600 seconds of the heat exposure on the specimen. In addition, lateral flame spread is observed to determine whether the flame front reaches the outer edge of the larger specimen wing at any height between 500 and 1000 millimetres (mm) during the test.

The gross calorific potential test of EN ISO 1716 determines the potential maximum total heat release of a product when burned completely. A powdery test specimen is ignited in pressurized oxygen atmosphere inside a closed steel cylinder (known as a "calorimetric bomb") surrounded by water jacket. The temperature rise of water during burning is measured. The gross calorific potential is calculated on the basis of the temperature rise, specimen mass, and correction factors related to the specific test arrangement used.

The purpose of the non-combustibility test of EN ISO 1182 is to identify the products that will not, or significantly not, contribute to a fire. A test specimen of cylindrical shape is inserted into a vertical tube furnace with a temperature of about 750 °C. Temperature changes due to the possible burning of the specimen are monitored with thermocouples. The flaming time of the specimen is visually observed. After the test, the mass loss of the specimen is determined.

Returning to the first aspect, typically, the barrier may comprise a fire protection layer. This is anticipated as providing at least part of the non-combustible at least a portion of the barrier The fire protection layer provides a component that contributes towards the ability of the platform to provide a firebreak and therefore provide the contribution to the fire performance of the platform.

The fire protection layer may provide protection by being treated before installation in the platform, or may provide protection by any suitable means.

Typically the fire protection layer may be a non-combustible material. This means the fire protection layer inherently provides fire protection that cannot be removed without removing at least a significant portion of the layer since the protection cannot be reduced by wear as would potentially be the case with treatments applied before installation.

The fire protection layer may be any suitable material, such as a single material, or a combination of materials. Typically, the fire protection layer is a composite material. By using a composite material the various constituents can be chosen to each provide their own advantages to the final material without detracting from the overall performance as may be the case with simple combinations of materials since these may have distinct areas of one material or another.

The fire protection layer may be any material that provides suitable fire protection. This could include titanium or alloys thereof, aluminium or alloys thereof or a ceramic. However, typically the fire protection layer may be foamed concrete. This provides a cheap and relatively light material for the fire protection layer since the weight is only 800 kg per cubic metre (m3) compared to a weight of about 2,400 kg/m3 for standard concrete while still providing a non-combustible layer. This makes installation and transport simpler and cheaper. The use of foamed concrete also has the advantage that the layer is a type of concrete and concrete is well known and accepted by the building and construction industry, so does not present a deviation from familiar materials for a user, purchaser or installer.

There are certain materials that are considered to meet the Euroclass Al classification without testing. These materials include concrete, cement, iron, steel, stainless steel, ceramics, zinc and zinc alloys, aluminium and aluminium alloys, glass and glass ceramics. These materials are considered to meet this rating by European Union Commission Decision 96/603/EC as amended by Decisions 2000/605 / EC and 2003/424 / EC.

Like most forms of concrete, the foamed concrete may require reinforcing bar (rebar) within it to assist in strengthening and holding the form of the concrete.

Typically the foamed concrete includes stainless steel reinforcing bar. The use of stainless steel rebar reduces the effect of water on the strength of the concrete. Since the concrete is foamed, it is porous, and therefore allows water to pass into and through it. Standard practice is to use mild steel for rebar.

However, this would rust if used in foamed concrete, which would not occur when using stainless steel rebar. Glass or glass resin may also be used in addition to or as an alternative to the stainless steel rebar while still providing the same function and advantages as well as being lighter than stainless steel thereby reducing the weight of the foamed concrete layer when used in place of all or some of the stainless steel rebar.

The fire protection layer may be a (i.e. at least one, or one or more) cemenfitious panel(s). This allows cheap, light, pre-fabricated panels to be used as the fire protection layer significantly reducing the weight of the platform over a corresponding platform made from standard materials (such as steel, aluminium, concrete, cement and glass) for standard platforms. The pre-fabrication element also allows rapid manufacture enabling higher production throughput, and makes transport and installation simpler and cheaper. Such panels are typically thin (of the order of about 1 to 5 cm thick), meaning they take up minimal space in the platform. The cementitious panel may also be referred to as a cement particle board, and may be A2 or A1 fire rated.

The cemenfifious panel may be coated in a sealant. This provides weather protection to the cemenfitious panel should it be exposed to the weather when forming part of the platform.

The sealant may be water resistant. This provides protection against water damage to the cemenfifious panel, such as swelling and contraction during a wetting and drying cycle. By water resistant it is intended to mean waterproof or water repellent.

The sealant may be fire resistant. This provides additional protection against fire, such as in the form of a fireproof encapsulation By fire resistant it is intended to mean fire retardant of non-combustible.

Of course, the sealant may be fire resistant and water resistant thereby providing the advantages of each.

The fire protection layer may be located at any suitable location relative to other components of the platform, such as on an upper or lower surface. Typically, the fire protection layer is contained within the platform. This provides protection for the fire protection layer during transport, installation and use, reducing the need or amount for the fire protection layer to be impact, abrasion and/or physical wear resistant. This increases the lifespan of the fire protection layer and reduces the likelihood of failure from non-fire related means.

The barrier may further comprise a frame for connection to a support structure and is arranged in use to be load bearing, the frame defining a minimum area of the platform. This provides the platform with its own support structure by providing a component that can be used to support, hold and/or fasten other components. For example, the fire protection layer may be supported by the frame. This allows the fire protection layer to be held securely. Of course, the support may be provided by fastenings, provision of a surface on which the fire protection layer sits or by providing a seat of other arrangement for holding the fire protection layer The fire protection layer may be encircled by the frame. This provides protection for the fire protection layer during transport, installation and use referred to above. By the term "encircled" it is intended to mean surrounds in a single plane, although it may mean surround in further planes or dimensions as well. The frame encircling the fire protection layer may be achieved by the frame having apertures in which the fire protection layer can be located.

The frame may be non-combustible. This means the core structure of the platform will withstand fire and contribute towards the firebreak effect. This may be achieved by the material from which the frame is made, which may be any suitable material. Typically, the frame may be stainless steel. Although stainless steel is heavier than some other possible options, such as aluminium, stainless steel is stronger than many of the alternatives while still being non-combustible.

The frame may be coated. This provides extra protection for the frame. For example, the frame may be galvanized. This protects the frame against corrosion or oxidation, which may increase on exposure to fire.

The barrier may further comprise a seal between the frame and the support structure. This removes any gap between the platform and the support structure to which it is connected in use. This reduces the likelihood of flames passing between the platform and the support structure and therefore enhances the ability of the platform to act as a fire break by removing the possibility of any fire passing between the platform and the support structure.

The seal may be any suitable material. Typically the seal may be an intumescent strip. The properties of the intumescent strip cause it to swell on exposure to heat and/or flames. This reinforces the seal provided by the strip should there be a fire, thereby improving the effectiveness of the seal.

The platform may weigh up to 1,000 kilograms (kg). This allows the platform to be hung from a tower crane at the end of the tower cranes reach. This reduces the number of tower cranes needed on a building site where platforms such as this are installed, which reduces overall constructions costs and the risks associated with operating multiple tower cranes. The platform may of course have a weight greater than or equal to 1,000 kg, such as when a larger platform is used.

Typically, each non-combustible component may have at least a one-hour fire safe rating. Further, each component of the platform may have at least a one-hour fire safe rating. These features enhance the ability of the platform to provide a firebreak and also reduce the likelihood of one or more components burning during a fire. The one-hour fire safe rating may correspond to Euroclass A2 classification.

The platform may be arranged in use to connect to the support structure by a socket and bracket connection, one of the platform or support structure having a socket and the other of the platform and support structure having the bracket. This allows rapid install of the platform, reducing "hang time" on a crane, and therefore reducing the installation cost and thereby the cost to the construction company.

According to a second aspect, there is provided a cantilever platform for providing a firebreak, the platform being arranged in use to connect to a support structure and to extend laterally outward therefrom, the platform comprising a barrier spanning an area parallel to the lateral extension, at least a portion of the barrier comprising a non-combustible fire protection layer provided by foamed concrete, the barrier being arranged in use to prevent fire transmission between opposing sides of the barrier According to a third aspect, there is provided a cantilever platform for providing a firebreak, the platform being arranged in use to connect to a support structure and to extend laterally outward therefrom, the platform comprising a barrier spanning an area parallel to the lateral extension, at least a portion of the barrier comprising a non-combustible fire protection layer provided by a cemenfitious panel, the barrier being arranged in use to prevent fire transmission between opposing sides of the barrier These platforms each provide a platform capable of acting as a firebreak by using a lighter material than materials used in standard platforms, making manufacture, transport and installation simpler and cheaper.

BRIEF DESCRIPTION OF FIGURES

Example cantilever platforms are described in detail below with reference to the accompanying figures, in which: Figure 1 shows a portion of a first example platform; Figure 2 shows a portion of a second example platform; Figure 3 shows the first example platform with exposed components; and Figure 4 shows an example bracket and socket for an example platform.

DETAILED DESCRIPTION

Two example cantilever platforms are described below. Each of these is a balcony. As set out above, the platforms could alternatively be a stage, staircase or other form of cantilever platform. A key aspect of the platform, whatever form it takes, is the ability to act as a firebreak due to the barrier the platform includes extending across at least a part of its lateral extension from the support structure to which the platform is connected in use.

Turning to the examples, a first example platform is generally illustrated at 1 in Figure 1. This platform is shown in an "in use" state, by which we mean in a state in which it has been connected to a support structure, which is shown at 1000 in Figure 1, and from which it extends laterally. Typically the support structure is a building when the platform is a balcony with a wall 1010 providing a façade to the building.

The platform 1 has a frame 10, which in use is load bearing (i.e. it is capable of supporting a load applied to the platform). In this example, the frame is formed of three legs 101, 102, 103, which extend outward from a bracket 500 and socket 600 (shown most clearly in Figure 4 and described in more detail below in relation to Figure 4) connecting the platform to the support structure. The legs are arranged with one leg at either side of the platform and one in the centre.

In this example the legs 101, 102, 103 are each connected to the adjacent leg or legs (depending on whether the respective leg is one of the legs at a side of the platform or the leg in the centre) by crosspieces 104, 105 at an end of the legs distal to the support structure 1000. Further crosspieces 106, 107 connect each leg to the adjacent leg or legs at an end of the legs proximal to the support structure. This means the frame 10 has the shape of an "8" the outer perimeter of which defines the minimum area of the platform.

In this arrangement, and in the example shown in Figure 1, the platform has a width (i.e. in the distance across the platform in the direction parallel to the wall 1010) of about 2.25 m and a depth (i.e. the distance between the distal end of the legs 101, 102, 103 and the wall) of about 1.5 m. Should a larger platform be wanted, the length of the legs can be extended to make the depth larger or extra legs can be added to make the width larger.

As set out in more detail below, the legs are typically located at a standard separation from each other. As such, if additional width is wanted but that additional width is insufficient to extend the width the full distance to where the next leg would be located while maintaining the standard separation, arms (not shown) are connected to the relevant leg, the arms extending perpendicular to the longitudinal axis of the leg.

The legs 101, 102, 103 and crosspieces 104, 105, 106, 107 are each galvanized stainless steel beams. The crosspieces and the legs at the ends of the plafform are each C beams in this example and the leg at the centre is a square or box tube/beam. These beams typically have a height of about 10 cm to 20 cm. In other examples, other shapes of beam may be used, such as a universal beam or I-beam. Regardless of the type of beam used, the beams are joined by welds and/or bolts. In some examples, the frame 10 is a single piece.

The shape of the frame 10 provides two apertures 11. These apertures reduce the weight of the platform and are filled with a fire protection layer. In this example, the fire protection layer is provided by cementitious panels 12.

While the arrangement, orientation, shape, size and/or number of panels is able to be altered depending on the example, in the example shown in Figure 1, there are two cementitious panels 12 provided per aperture 11 (with Figure 1 only showing one aperture filled with cementitious panels). Each cementitious panel is rectangular in shape and is orientated with the longitudinal axis generally parallel to the longitudinal axes of the legs 101, 102, 103. In this example the two panels abut each other along one of their long sides.

The cementitious panels are about 1 m long, about 40 cm wide and about 2 cm thick. The cementitious panels may be a panel provided by Euroform, such as an A2 Versapanel. To maintain structural integrity of the panels during inclement weather the panels are treated with a fireproof and waterproof sealant. The sealant may be a Rawlins sealant, such as a Thermoguard paint, e.g. Thermoguard asbestos encapsulating paint (this may be used even though there is anticipated to be no asbestos in the cementitious panels).

The aperture 11 shown in Figure 1 that is not covered by cementitious panels 12 in the figure shows the elements that provide support for the cementitious panels. This includes trays 13 attached to the crosspieces 104, 105, 106, 107. These trays are wide pieces of "L" shaped metal strip. The trays are attached to the crosspieces with the "L" inverted to provide a shelf for the cementitious panels. This means the weight of the cementitious panels sits on top of the trays instead of hanging from the trays. One tray is provided at either end of each cementitious panel.

At the sides where the cementitious panels 12 abut there is a central strut 14 extending between the crosspieces 104, 105, 106, 107 defining sides of the respective aperture 11 to which the central strut is also attached. This provides support to the cementitious panels along the sides at which they abut. Each central strut is a stainless steel square tube.

Further support is provided by cross deck supports 15. These extend between and are attached to adjacent legs 101, 102, 103. In this example these fit over the central strut 14 due to a notch in the centre of each cross deck support. The cross deck supports provide support at various places across each cementitious panel 12. Each cross deck support is a stainless steel plate.

During manufacture, once the frame 10 and supporting elements in the form of the trays 13, central struts 14, cross deck supports 15 are connected to the frame, the cementitious panels 12 are able to be placed in the apertures 11.

When connected to the support structure 1000, there is a gap between the frame 10 and the wall 1010 due to the bracket 500 and socket 600. In the example shown in Figure 1 there is an intumescent strip 16 provided in this gap to provide further fire protection since this is configured to expand on the application of heat, thereby reinforcing the seal provided by the strip between the frame and the support structure. The intumescent strip may be a Rockwool (RTM) product such as the Intumescent Expansion Joint, which is also referred to as the Intumescent Expansion Joint Seal.

A second example platform is generally illustrated at 2 in Figure 2. This has a frame 20. This frame has the same structure as the frame 10 of the example shown in Figure 1. As such, the frame of this example has legs 201, 202, 203, which extend outward from a bracket 500 and socket 600 and which are arranged with one leg at either side of the platform and one in the centre.

The legs 201, 202, 203 are also joined by crosspieces 204, 205, 206, 207. As with the example shown in Figure 1, the crosspieces connect adjacent legs at an end of the legs distal to the support structure 1000 and at an end of the legs proximal to the support structure. This means the frame again has the shape of an "8", with its outer perimeter defining the minimum area of the platform 2. The legs and crosspieces are also galvanized stainless steel like the example of Figure 1.

The shape of the frame 20 again provides apertures 21 defined by the arrangement of the legs 201, 202, 203 and the crosspieces 204, 205, 206, 207.

Instead of cemenfifious panels, this example includes a foamed concrete block 22 as a fire protection layer in each aperture. Whereas the cemenfifious panels are pre-fabricated before installation, the foamed concrete is typically poured into a mould that includes the frame 20.

As with Figure 1, Figure 2 only shows the foamed concrete block 22 in one aperture 21 of the frame 20 in order to show the support structure for the foamed concrete. To provide a connection between the frame and the foamed concrete, rebar portions 23 are connected along the sides of the legs 201, 202, 203 defining a side of the apertures. The rebar portions are "U" shaped stainless steel reinforced bars. Although not shown in this examples, in some examples the rebar portions may be glass or glass resin, and/or the foamed concrete may contain further stainless steel and/or glass or glass resin rebar.

An intumescent strip 24 is provided in the gap between the frame 20 and the wall 1010 of the support structure 1000 to which the platform 2 is connected in used caused by the backet 500 and socket 600. This is the same intumescent strip and performs the same functions as the intumescent strip shown in the example of Figure 1 In each of the examples shown in Figures 1 and 2, the fire protection layer, frame and intumescent layer provide a barrier. Since each of these elements is non-combustible, the barrier prevents fire from passing between major faces of the platform (by which we mean the upper and lower faces of the platform since they are the largest faces of the platform). This causes these examples of the platform to provide a firebreak, which will reduce the tendency of fire to spread vertically up the exterior of a building when the platform is connected to the building.

To provide a balcony in the form expected by a user of the balcony, some further features are typically (although ultimately optionally) included. Figure 3 illustrates an example including these features based on the platform 1 shown in Figure 1. The platform 2 shown in Figure 2 could also be used with these features of Figure 3 since the only differences are the use of cementitious panels and the corresponding support structure. The other features could still be used in the same form and in the same way.

Figure 3 shows a platform 3 having a frame 30 in the same form as the frames of Figures 1 and 2 (and therefore having legs and crosspieces). Located across the cementitious panels 12 (or if foamed concrete is used, the foamed concrete) shown in Figure 3 are decking supports 31. These extend parallel to the axes of the legs from one end of the legs to the other and are spaced at intervals along the width of the platform.

At a side of the platform 3 distal to where the platform connects to a support structure (not shown in Figure 3) the decking supports 31 abut a glazing channel 32 from which glazing 33 extends upwardly. There are also glazing channels along the other outward facing sides (so only not on the side that connects to the support structure) from which glazing extends upward. The glass in this example is generally upright.

Covering the sides of the platform 3, there are cladding panels 34. These hide the legs and crosspieces and are located below the glazing channels. The underside of the platform, although not shown in Figure 3 is covered by soffit trays 35.

Figure 3 also shows an opening in the cementitious panel 12. This is purely for illustrative purposes, and shows the underlying support structure including a cross deck support 15.

As set out in more detail below in relation to Figure 4, Figure 3 also shows the brackets 500 and sockets 600 that provide the connection between the platform 3 and the support structure along with the lock 700 for the bracket and socket.

The decking supports 31 provide rails on which decking 36 is supported. The decking is a composite material shaped into planks. In this example the planks lie across the decking supports perpendicular to the supports. An example decking that would be suitable to use is Armour-Dek (RTM) decking.

As mentioned above, the construction of the platform is generally the same irrespective of whether cementitious panels or foamed concrete is used. The only significant difference between these two types of platform is the overall weight of the platform. A platform that uses cementitious panels is lighter than a platform that uses foamed concrete. This is due to the difference in weight of the cementitious panels and the foamed concrete. For example, each cementitious panel may be about 65 kg, with each platform using these having four panels in some examples; this is in comparison to platforms of some examples, which have blocks of foamed concrete, having two blocks of foamed concrete, with each being about 400 kg. The precise weight of a cementitious panel or block of foamed concrete is of course determined by their dimensions. The difference in weight between the panels and foamed concrete can be seen to create a significant difference in the overall weight of the platform depending on which of the panels or foamed concrete is used.

The platform in each of the examples described above is typically installed on a building by a tower crane. The platform is connected to the hook of the crane and lifted into position adjacent a building to which it is to be installed. In order to allow the tower crane to lift the platform and hold it at the maximum extent of its reach, the platform is intended to weigh no more than 1,000 kg (i.e. 1 metric ton).

In order to allow for a quick installation, and therefore achieve minimum "hang time" on the crane, the platform has a bracket 500 as shown in Figure 4. The bracket is a wedge shaped plate 501 on the end of each leg 401, 402, 403 of the frame of the platform.

On installation, the plate 501 of each bracket 500 is lowered into a slot 601 of a socket 600 by lowering the platform. Each slot is a complementary shape to the corresponding plate.

Each socket is itself attached to the support structure to which the platform is being connected by a plate 602 that is attached to fastenings embedded in the building. The sockets are located at a predetermined width apart. This separation is determined by the underlying structure of the building and where support columns and beams are located, which is typically standardised across the building industry, meaning the sockets will typically be located at a standard separation regardless of the building on which they are used.

Once the plates 501 of the brackets 500 are located in the slot 601 of each socket, the platform is levelled by adjusting the bolts 603 in the sockets. A lock 700 is then placed over the top of the bracket and socket and secured in place using bolts 701.

During installation, once the platform is suitably secure, the platform is disconnected from the hook of the crane. Typically the platform can be removed from the hook of the crane within about ten minutes of being lowered on to the sockets 600.

Additionally, during installation, the intumescent strip is inserted between the frame and the wall against which the platform is being installed.

Claims

CLAIMS1. A cantilever platform for providing a firebreak, the platform being arranged in use to connect to a support structure and to extend laterally outward therefrom, the platform comprising a barrier spanning an area parallel to the lateral extension of the platform, at least a portion of the barrier being non-combustible, the barrier being arranged in use to prevent fire transmission between opposing sides of the barrier.
2. The cantilever platform according to claim 1, wherein the barrier comprises a fire protection layer
3. The cantilever platform according to claim 2, wherein the fire protection layer is a non-combustible material
4. The cantilever platform according to claim 2 or claim 3, wherein the fire protection layer is a composite material.
5. The cantilever platform according to claim 4, wherein the fire protection layer is foamed concrete.
6. The cantilever plafform according to claim 5, wherein the foamed concrete includes stainless steel reinforcing bar.
7. The cantilever platform according to claim 4, wherein the fire protection layer is a cementitious panel.
8. The cantilever platform according to claim 7, wherein the panel is coated in a sealant.
9. The cantilever platform according to claim 8, wherein the sealant is water resistant.
10. The cantilever platform according to claim 8 or claim 9, wherein the sealant is fire resistant.
11. The cantilever platform according to any one of claims 2 to 10, wherein the fire protection layer is contained within the platform.
12. The cantilever platform according to any one of the preceding claims, wherein the barrier comprises a frame for connection to a support structure and is arranged in use to be load bearing, the frame defining a minimum area of the platform.
13. The cantilever platform according to claim 12 as dependent on claim 2, wherein the fire protection layer is supported by the frame.
14. The cantilever plafform according to claim 12 or claim 13, wherein the fire protection layer is encircled by the frame.
15. The cantilever platform according to claim 12 or claim 13, wherein the frame is non-combustible.
16. The cantilever platform according to claim 14, wherein the frame is stainless steel.
17. The cantilever platform according to any one of claims 12 to 15, the barrier further comprising a seal between the frame and the support structure.
18. The cantilever platform according to claim 15, wherein the seal is an intumescent strip.
19. The cantilever platform according to any one of the preceding claims, wherein the platform weighs up to 1,000 kilograms (kg).
20. The cantilever platform according to any one of the preceding claims, wherein each non-combustible component has at least a one-hour fire safe rating.
21. The cantilever platform according to claim 20, wherein each component of the platform has at least a one-hour fire safe rating.
22. The cantilever platform according to any one of the preceding claims, wherein the platform is arranged in use to connect to the support structure by a socket and bracket connection, one of the platform or support structure having a socket and the other of the platform and support structure having the bracket.
23. The cantilever platform according to claim 22, wherein the bracket forms part of the platform and the socket forms part of the support structure, the bracket being configured to be received in a slot of the socket, the slot facing upwards in use.
24. A cantilever platform for providing a firebreak, the platform being arranged in use to connect to a support structure and to extend laterally outward therefrom, the platform comprising a barrier spanning an area parallel to the lateral extension, at least a portion of the barrier comprising a non-combustible fire protection layer provided by foamed concrete, the barrier being arranged in use to prevent fire transmission between opposing sides of the barrier.
25. A cantilever platform for providing a firebreak, the platform being arranged in use to connect to a support structure and to extend laterally outward therefrom, the platform comprising a barrier spanning an area parallel to the lateral extension, at least a portion of the barrier comprising a non-combustible fire protection layer provided by a cementitious panel, the barrier being arranged in use to prevent fire transmission between opposing sides of the barrier.