Patent Publication Number: US-2010116355-A1

Title: Zero height roof

Description:
FIELD OF THE INVENTION 
     This patent specification relates to rainwater capture. More particularly this specification relates to a roof system for the collection of rainwater. 
     BACKGROUND OF THE INVENTION 
     Mankind faces water shortage in many places around the globe. Desalination is costly and power hungry. The roofs of houses, commercial, civic and governmental structures have been used to capture precipitation falling upon the external shell of these buildings. Generally speaking it is the roofs of the buildings which are most to often used for this purpose. There have been many forms of building structure developed over the ages with the external cladding being usually of ceramic, cement, stone, metal, plastic, cloth or timber. In some instances a combination of two or more of these materials have been used. The buildings are generally erected such that the roof is above a floor of the building which is adapted for carrying the contents of the building. Other forms of roofed buildings developed by man include greenhouses and the like for sheltering plants and livestock with the floor being sometimes the bare ground. These known buildings roofs are a cover for a three dimensional space laying under the roof with the space being the or at least a prime objective of the building. The known building is substantially rigid and so if one wishes to make a very large scale building there comes to light problems associated with thermal expansion and ground movement beneath the building which can cause the building to become distorted due to differing expansion coefficients and thereby lead to roof and building failure. To ward against this builders have sought to create monolithic foundations being very rigid so distortion can be minimized as distortion becomes a greater concern the larger the building and is a limiter of building scale. An ancient prior art attempt to capture rainwater may be found in Spain which involves the tiling with rock shards of a dell or ground hollow which has had a cistern formed at its base. The resulting collection system is difficult, haphazard, costly and laborious to construct even in very small scale. The invention provides substantial solutions for the aforesaid problems band provides a roof structure which is relatively cheap and is able to cope with significant distortion due to ground movement and thermal excitement. 
     DISCLOSURE OF THE INVENTION 
     We have invented a zero height roof which can be easily scaled to cover very large land areas to create a rainwater catchment very cheaply. The down force of the mass of the roof is not carried entirely by the stay means (if at all) as is the case with the prior art device as the tension truss rests upon the ground or spacer means mounted upon the ground. There is a small gap between the roof sheeting or tiles and the underlying ground. 
     The zero height roof is a tensioned member, ground covering water collection system. The tension member is preferably a cable, wire or chain which is adapted to to be pulled taught between stay means anchored to the ground. The roof undercarriage is formed of a plurality of such members tensioned between stay means. Preferably the tension members are arranged parallel to each other and are pulled taught over an convex or arched ground surface. 
     The zero height roof in a preferred embodiment largely conforms to the underlying topography of the land over which it is tensioned and mounted and is therefore significantly different from the prior art in both objective and function. The volume under the zero height roof is therefore at least partially filled with the land which it covers. The zero height roof which is drawn tight over the arch or convex of land it covers and in effect houses the land it covers. It is a roof whose underlying “building” is the ground and whose contents is the ground. 
     In many respects the trusses and batons of the invention form a net over the ground they are laid over. The net conforms itself to the shape of the land underlying it because it is pulled tight over the shape of the ground like a tight elastic sock conforms itself to a foot when it is drawn over the foot. Of course in the light of the invention it can be seen that in order for the net to be pulled tight into conformity with a dell or hollow of the ground a portion of the net must be secured into the hollow by means capable of holding it in the dell or hollow so that it conforms to the shape of the dell or hollow and accordingly the invention in this broad form includes truss hold down means being secured to the ground and able to constrain the truss at that location it engages the truss to be at a small height relative the surface of the dell or hollow. Each of the trusses is an elongate member elongate along a respective axis. Each of the baton means is an elongate member elongate along a respective axis extending in a transverse direction relative to the longitudinal axis of the truss it is mounted to. 
     In a preferred embodiment of the invention the zero height roof is a tensioned truss, ground covering water collection system. The tension truss is an elongate member elongate along an axis and is preferably a cable, wire or chain which is adapted to be pulled tight by tensioning means between stay means anchored to the ground. The roof undercarriage is formed of a plurality of such trusses tensioned between stay means. Preferably the tension trusses are arranged parallel to each other and are pulled tight over a convex or a arched ground surface. Secured to the tension trusses are baton means and roof sheeting or tiles are mounted onto the baton means. There may be included spacer means between a tension truss and the ground. There may be included spacer means between a tension truss and a baton. There may be included spacer means between a baton means and a roof sheet/s or tile/s. Preferably each respective tension truss is held at or adjacent its ends by holding means associated with the stay means. 
     In a preferred alternative embodiment of the invention the zero height roof is a tensioned truss and tension baton ground covering water collection system. The tension truss is an elongate member elongate along an axis and is preferably a cable, wire or chain which is adapted to be pulled taught by tensioning means between stay means anchored to the ground. The roof undercarriage is formed of a plurality of such trusses tensioned between stay means. Preferably the tension trusses are arranged parallel to each other and are pulled taught over a convex or a arched ground surface. Secured to the tension trusses are tension baton means pulled taut between stay means and roof sheeting or tiles are mounted onto the tension baton means. Each of the tension baton means being elongate along a respective axis. There may be included spacer means between a tension truss and the ground. There may be included spacer means between a tension truss and a tension baton means. There may be included spacer means between a tension baton means and a roof sheet/s or tile/s. Preferably each respective tension truss is held at or adjacent its ends by holding means associated with the stay means. Preferably each respective tension baton means is held at or adjacent its ends by holding means associated with the stay means. Preferably the longitudinal axes of the tension trusses extend at a transverse angle relative to the longitudinal axes of the baton means. 
     In another preferred embodiment of the invention at least one truss is held aloft the ground surface by riser/spacer means such that there is a small distance between the truss and the ground. 
     The economic rationale for constructing a zero height roof is simple, for example, in Australia the average annual rainfall is approx 400 mm equating to 0.4 of a gigalitre per 100 hectares of land p.a. Evaporation rates may exceed the annual rainfall by a considerable margin. The rainfall run off rate may be less than 1% in many locations equating to 0.004 of a gigalitre annual runoff per 100 hectares. A zero height roof of 100 hectares operating in such environs would generate as much run off therefore as 10,000 similarly sited but uncovered hectares. When considering the Sydney Basin it can be seen in the historical record that it receives on average approx 1300 mm p.a. equivalent to 1.3 gigalitres per square kilometre or 100 hectares p.a. and at AU$3.00 per kilolitre sale price this equates to AU$3.9 million p.a. in earnings. A 5000 hectare site would produce approx 65 GL p.a. equivalent to AU$253.5 million earnings. On current pricing as of year 2007/8 we estimate the zero height roof could be constructed for approx $AU40.00 per square metre and there being 1,000,000 square metres per square kilometre or 100 hectares. A 5000 hectare zero height roof would cost therefore around than AU$2.0 billion and would return on average approx 14% on capital outlayed which is more than enough to service finance costs and operating expenses whilst turning a modest profit for the zero height roof owner. What is more the zero height roof is more than competitive with regards to desalination and other measures being proposed. The inventions&#39; benefits become readily apparent when one considers that unlike desalination the zero height roof does not require an ongoing source of energy to produce its water as it simply collects rain falling from the sky. Because there is no conventional building as such under the roof there is a huge cost saving over conventional building methods. 
     The ground over which the invention is tensioned is preferably arched like a rainbow. The ground may be naturally arched such in topography or may be cut to this topographical shape by cutting means or it may have material added onto to it such that an arch is formed. Preferably the cutting means are machine cutting means but it is envisaged that animal or human means may be employed to do the job. Preferably the machine cutting means is laser guided. It is preferable that the invention be produced in the following manner: take a parcel of land having a length and a width, let the length be longer than the width such that in top plan view the parcel is rectangular, let the ground be arched as above with the arch extending across the width of the parcel, let there be stays placed adjacent the wide edges of the parcel, let tension trusses be laid out over the width of the parcel, let the trusses be tensioned between the stays with the stays holding the tension, let batons be located adjacent the trusses and then let there be roof sheeting mounted onto the trusses, let there be at least one gutter for collecting runoff from at least one of the wide edges of the zero height roof. In an alternative arrangement the trusses may be held aloft the ground surface by means of riser/spacer means. The riser/spacer means being sandwiched between the truss underside and the ground or a mounting pad located on and or in the ground. The invention is also suited to covering undulating ground and it is also suited to covering sloped ground. As stated above it is possible to add material to a portion of ground to form the arch over which the roof is tensioned. In a alternative embodiment of the invention a flexible bladder means is formed and laid upon the ground. The tension members are drawn tight over the bladder means which has been at least partially filled. The bladder means when at least partially filled and clamped to the ground forms an arch of its top surface. Preferably the bladder means may be filled with gas and or liquid however it is envisaged that solids may also be used to fill the volume of the bladder means. In yet another variation of the invention the bladder means may be filled with material which cures or sets such that the arch formed is solid having substantially no flexure. An advantage of using flexible bladder means to form an arch is that minor irregularities in the topography of the underlying land can be smoothed out or compensated against so that the upper surface of the bladder is unperturbed by the irregularity. Another advantage in an alternative embodiment is that the bladder means can be adapted to tension the tension members of the roof. The tension members being secured by securement or holding means to stay means and the bladder means filled below the tension members so as to lift the tension members aloft and into tension against their securement at their ends with the stay means. The bladder means may include at least one upper surface and at least one lower surface. Preferably the upper surface of the bladder means is flexible. Preferably the lower surface of the arch is flexible. It is envisaged that the bladder means be filled with liquid or gas and then solids are pushed into the internal volume of the bladder means so as to reduce the bladders&#39; flexibility. A preferred bladder means may be formed of any suitable material but is not limited to the following list of materials: metal, plastic; polycarbonate; cellulose, rubber. In another variation the bladder means may be filled with hard setting foam akin in function to that which fills surf boards and the like. As an alternative to forming a bladder discrete from the roof is to use the roof sheeting or tile means as the upper surface of the bladder and the ground as the lower surface of the bladder. This allows the bladder so formed to be filled up so as to pump up the tension members of the roof into tension against the stay means. In yet another embodiment of the invention a roof is formed using roof sheeting means which forms the upper surface of a bladder and preferably the ground being the lower surface of the bladder. The ends of the roof are held by stay means at least until the volume under the roof has been filled with material and has lifted the roof into its arched shape. The stay means serving to anchor the so pumped up roof to the ground. With respect to filling bladder means of the invention a number of substances may be used to form the task. A particularly preferable filling material is vermiculite as a foam which may be set hard as it is used in heat protection for structural members in conventional buildings. Preferably however the bladder which may be used to form a suitably shaped profile for tensioning a roof over is a self contained unit from the undercarriage and roof sheeting or tiles of the roof. If the bladder means is of a type which has a top layer being a flexible membrane and the bottom layer being the underlying ground or layer upon it then it is preferable that the tension members be able to move independently of the bladder means so as expansion and contraction of the undercarriage can occur. 
     The zero height roof is preferably clad with non porous roofing cladding such as metal, plastic, polycarbonate or fibrous cement sheeting. Because in preferred forms of the invention the ground underlying the roof is cut off from rainfall events there is a strong likely hood in some circumstances for the ground underlying the roof to dry out and shrink. And to overcome this we have invented water introduction means. The invention therefore may include water introduction means located beneath the roof surface so that a quantity of water may be added to the underside of the roof thus offsetting against the possibility of excessive shrinkage due to dry out. The water introduction means may simply spill water onto the ground surface beneath the roof or in a preferred embodiment an outlet of the introduction system may be located under the ground surface so that the introduction is made into the ground at a depth distant from the zero height roof upper surface. To measure the amount of water in the ground under the zero height roof there may be included hydrology measurement means. The measurement means may take the form of a water sensitive probe located in the ground underlying the roof and or above the ground underlying the roof. The underside of the roof may include probes for measuring temperature, hydrological conditions or even sunlight so as to report any breach of the upper surface. The small volume under the roof may present a habitat for certain animals, insects and plants and to control this environment it may be needed that the ground is treated or coated with at least one substance which deters the use of the volume as a habitat. The sides of the zero height roof may need to be netted or filled in so as to restrict the passage of life forms under the roof or from the use of the roof as a refuge. 
     If there is a riser otherwise known as a spacer means employed to hold the truss a small distance above the ground in a particular rendition of our invention it may be of a fixed shape or dimension or it may be that the riser is made of spring material such that it may tension the truss to which it is employed to hold aloft the ground. The riser of the invention may be a post like member in some embodiments whereas in others it may be a channel type member. The function of the riser may be to hold the truss above the ground surface at a set height or a variable height. The riser means may be secured into the ground or it may be sat upon the ground as required. 
     Stay tensioning means of the invention may be hand adjustable tension means or hydraulic or magnetic or any other suitable arrangement such that the truss can be tensioned adequately for the purpose. The tensioning means may include mechanical tensioning ability. In another preferred embodiment of the invention the tensioning means may be incorporated into the truss of the invention. The truss of the invention may include at least one threaded end which can be passed through an eyelet or slot in a stay means so that the truss can be tightened between the stay means. Therefore it is evident that if required at least one truss of the invention may include means to tighten the truss between stay means. 
     The stay means of the invention may be adapted to stay at least one truss of the invention. It is preferable that each stay means restrain at least one truss. In another preferred embodiment a stay means may restrain more than one truss. The tensioning means may be preset or it may be dynamic so that the structure can cope with thermal expansion issues and or wind conditions. 
     The truss of the invention may be a length of rope or wire or cable or chain or flexible strip or strap or, it may be that a truss of the invention is formed of a combination of the above list. The material forming the truss may be formed of organic or inorganic material. It may be formed of fibre glass or carbon fibre for example. The truss of the invention may include securement lugs or features for the mounting of a baton system upon it. The securement lugs or features may be attached to the truss by whatever means is practicable. The securement lugs or features may be swagged on or bonded on or welded on or formed from the truss material. It is preferred that the trusses of the invention are separate units but in another preferred embodiment more than one truss is formed by a length of truss material. 
     The baton of the invention may be a tension member or a non tensioned member of the roof structure. In another preferred form of the invention both the truss and baton of the invention are tensioned between respective pairs of stay means. The baton of the invention may include a locating feature for engagement with the truss of the invention. The baton of the invention may include a locating feature for engagement with roof sheet or tile means. 
     The roof sheet or tile of the invention may include at least one locating feature for engagement with or mounting on by a baton of the invention. The roof sheet or tile is preferably substantially non porous such that water does not pass through it. 
     As stated above in some embodiments it is preferable to include in the invention at least one spacer means between the truss and the ground over which the truss is tightened. The spacer means may be rigidly attached to or joined with the truss it supports or alternatively it may be include at least one movement means allowing the truss to move along its longitudinal axis relative to the spacer means and the ground. Preferably the movement means may include at least one rolling element on which the truss rides. The said rolling element being a load bearing bearing member such that the truss is a akin to rail carried by the wheel of the said rolling element. In an alternative arrangement the spacer means may include at least one sliding bearing surface onto which is adapted to be carried the truss so that the truss can move relative to the spacer means. The sliding surface being a load carrying bearing surface for the carriage of the truss. The sliding surface allowing the truss to move along its longitudinal axis relative to the spacer means and the ground. The truss having at least one surface for being carried by the rolling element or sliding surface. By including in the invention movement means associated with the spacer means thermal expansion and contraction forces and movement associated with same in the truss can be catered for without undue side ways load on the spacer means. The truss is in tension and so as the truss expands or contracts with heat and cold the truss is able to move relative to the spacer means along its axis because the truss is tensioned along its axis. In an alternative embodiment of the invention the truss may include a rolling element and or sliding surface arrangement which can be bourne by the spacer means. The spacer means including at least one surface onto which the rolling element or sliding surface arrangement of the truss may move against. In yet a further alternative arrangement a rolling or sliding surface means may be included between the truss and the ground or space element so that the truss can move along its longitudinal axis during expansion and contraction due to thermal excitement. In respect to the idea of allowing the truss to move along its axis it is envisaged that the said movement means can aid in the initial set up of the roof such that in assembling the roof the truss is able to be moved along its axis over the movement means. It is also envisaged that the truss is able to be secured to the spacer or movement means such that the truss is constrained to have freedom of movement relative the spacer means or movement means only along the longitudinal axis of the truss. In yet another preferred embodiment of the invention the truss is able to move both along its axis and along at least one axis being transverse relative to the truss longitudinal axis. 
     A zero height roof covering 5 square kilometres for example might expand and contract many millimetres due to thermal excitement of the truss material. By allowing the truss to move relative to the ground along its longitudinal axis and indeed transverse relative to its longitudinal axis the truss is able to ride the movement means or spacer means and thereby avoid excessive and potentially damaging unwanted loads on the truss and the spacer means. 
     The zero height roof may use conventional roofing sheeting attached to baton means and cable truss system which is pulled taught over the face of the ground and preferably kept in tension by tensioning means. In some embodiments of the invention a riser system is employed wherein the cable truss system is held above the ground surface such that a small gap is maintained between the truss and the land surface. 
     In a preferred forms of the invention the trusses and batons are flexible along their length and because at least the trusses are tensioned between stay means using dynamic tensioning means the structure is able to ride with the land it is mounted upon or over as and if it moves and also adjust to thermal expansion and contraction forces generated in the roof. This is a big inventive step forward over the prior art housing devices which are comparatively rigid and inflexible relative to the zero height roof and which fail with significant land movement 
     The invention in a preferred type employs cables to form a net like truss system which is arranged such that the cables are pulled taught over a hill or hill shaped stretch of land area. The trusses are preferably parallel to each other and overlaid and affixed with batons which are attached by attachment means to the trusses. The trusses are tensioned by tensioning means such that they are pulled tight over the contour of the ground. Roofing sheeting or tiles are attached to the batons. Preferably the batons are positioned above the or an upper surface of the trusses but may in some embodiments be partly positioned below the or an underside surface of the truss. In an alternative embodiment the trusses themselves may also be mounted to by the tiles or sheeting. Preferably the sheeting or tiles are formed such that they are corrugated or panned, although this is not always practicable. Preferably each truss is tensioned using adjustable tensioning means. The adjustment being preferably automatic and or manual in nature. A truss may be coated with a material or layers of material such that the truss is protected from the environment and in some circumstances if required within the confines of the particular embodiment wear against the soil which can be high in friction. In an alternative arrangement the truss may be laid into a channel type riser/spacer means for receiving the truss. The channel having an inner surface and an outer surface wherein the outer surface or at least a portion of it is in contact with the surface of the ground. The channel or spacer element being sandwiched between the cable and the ground. The channel may be formed of any conveniently suitable material or group of materials though plastic or metal is preferred. The riser/spacer may be U shaped and have a flat bottom or any suitable shape such that it is able to distribute load from the tensioned cable to the ground underlying the channel. The underside surface of the channel being preferably flat or possessing flats, although other surface shapes are contemplated. A riser channel may extend along the entire length of the truss or only a portion of its length and it is envisaged that a truss may be held aloft the ground surface by one or more riser/spacer means channels. 
     In a preferred form of the invention the truss is pulled tight over an arched strip of ground which may be of natural formation or be cut by machine means. It is preferable that each truss is a unit unto itself but it is envisaged that a cable be used to form one or more trusses of the system. It is preferable that the cable forming the truss be formed of metal wire but it is envisaged that other materials be used if and when the need arises. The truss may be formed from metal or glass fibre or carbon fibre or any suitable material or combination of materials. The batons of the system may be formed of any convenient material or combination of materials including but not limited to wood, metal, carbon fibre, plastic/s. The baton used in the system may be formed of wire or rod or bar. A baton may be a cable. A baton may be flexible along its longitudinal axis. A baton may be tensioned by tensioning means. The tensioning means may be incorporated into the baton or be associated with the stay means used to tension the baton. A truss may be formed from or include one or more cables or linked members. A baton may be formed from or include one or more cable or linked members. 
     The zero height roof may be used as a platform for a solar thermal water heating collector system. The roof sheeting of the invention may include a solar thermal heating system. The roof sheeting of the invention being close to the ground may be act as a thermal blanket trapping heat below the roof which can the be collected by heat collector means including fluid flow heat collector means. The ground underlying the zero height roof may be coated or other wise treated with a material which is able to absorb water vapor such that the underside of the roof does not sweat. The ground under the zero height roof may be treated so that its ph level is such that it does not form a strong alkali or strong acid such that the roof structure or portion of same is not corroded due either to contact with the ground or due to alkali or acid condensate due to sweating. The ground laying beneath the zero height roof may be treated such that it is a cide for at least one pest including insect pest or vermin or plant pests. Vermin proofing may be added to the underside of the roofed area and or to the or a edge of the zero height roof. 
     The invention is intended to be particularly useful for the provision of water to riparian systems which are drought stressed or otherwise having insufficient flow. For example the Murray and Darling rivers in Australia have had and may well continue to experience reduced water flow due to drought and to the over allocation of irrigation permits. The invention therefore in another preferred form includes the augmenting of these and other river systems with the invention. Another embodiment of the invention includes the setting up of at least one zero height roof in the range surrounding Sydney Australia and connecting it by piping means to the Warragamba dam either directly by pipe means or through at least one intermediate storage dam means and then by pipe means to the Warragamba dam and because of the large fall from the range top to the water level in the Warragamba dam it is possible to use the fall to generate electricity for use by energy consumers. The system, that is the zero height roof and the piping means and generating means and location of the zero height roof at the range top can act as an emergency power supply for the Sydney basin and surrounding environs. The piping may also be used to transfer water uphill from the Warragamba dam so that green energy producers have means made available to them to store electricity, that is pumped storage means. 
     Some parts of Queensland Australia and the far north eastern corner of N.S.W are very high rainfall areas, In fact there are a number of locations in these two states which receive in excess of 2000 mm of rainfall per annum and there are even places within these two states which receive more than 5000 mm per annum. It is envisaged that rainwater may be harvested by the zero height roof in at least one of these areas and preferably a piping system connected so as to pipe water from the said area to an area experiencing water scarcity. There is a fear amongst some in the community that water redirected from tropical environs to arid regions may bring with it life forms which are environmentally dangerous in an arid environment. The said life form being not from the and environment could hypothetically wreak havoc due to environmental competitiveness unbalancing. The zero height roof substantially overcomes this situation developing due to the fact that it will act as an interceptor of rainfall before it makes contact with the tropical landscape. The zero height roof prevents the water coming in contact with the land and the piping means further ensures that it remains out of contact with the environment. In far north Queensland for example there are sites which receive 8000 mm rainfall per annum so a one square kilometre zero height roof would on average receive eight gigalitres of rain per annum. A hundred square kilometers sized zero height roof would therefore be able to harvest 800 gigaliters per annum and by our estimates on current pricing would cost AU$5.0 billion approximately. On these numbers the zero height roof owner could sell the water harvested at AU$1.00 per kilolitre and still earn AU$800,000,000.00 per annum. A desalination plant for example capable of producing 800 GL of potable water per year would have a cost many multiples that of the zero height roof What is more desalination requires ongoing energy consumption to drive the desalination process and hence a substantial ongoing operational cost which must be bourne by the consumer or desalination plant owner. The invention is free from this cost and so it is evident that the service to mankind by our invention is enormous. 
     In many instances it may be that a suitable site for the erection of the invention will be located at a significant elevation relative to the eventual outlet of a piping system used for piping the water off the roof or storage means and so it is feasible in these circumstances to use the fall from the pipe inlet to its outlet to drive electric turbine means for the generation of electricity. It can be seen therefore that the zero height roof in many instances could be a contributor to energy reserves rather than a user of it as is the case with desalination and even for that matter ground water pumping arrangements. 
     The invention in another broad form includes the covering of a ground hollow or dell with the zero height roof, the ground hollow or dell being generally a concave arch. In this preferred embodiment the trusses of the roof are pulled tight along their respective longitudinal axes by tensioning means and the trusses are held close to the ground intermittently along the longitude of each truss by riser means which have been secured to the ground. The trusses are mounted to by baton means and tiles or sheeting means mounted atop of the baton means. In embodiments of the invention wherein the roof includes at least one concave roof portion it is preferable that the roof sheeting or tiles be highly reflective so that sunlight falling upon the reflective surface/s can be concentrated onto a collector means. The collector means being situated above the roof at a suitable focus distance. 
     The invention in another preferred embodiment is adapted to conform to undulating land such that the zero height roof includes at least one convex arch and at least one concave arch. 
     The invention in yet another broad embodiment includes tension batons which are tensioned between stay means which are adapted to be mounted onto non tensioned truss means. The tension batons being elongate along an axis extending in a direction which is transverse to the longitudinal axis of the truss. One must understand though that when we speak of axis of the truss or axis of the baton member that in some embodiments of the invention the truss and or the baton are not straight because they extend over an arch or around an arch so that the respective axis it is not straight. The tension batons are mounted on by tiles or roof sheeting. There may be included at least one spacer means between a respective truss and baton. The non tensioned truss may be laid out upon the ground or alternatively it may be held aloft the ground a small distance by truss raising spacer/riser means. 
     In still another embodiment of the invention the truss is a tension truss tensioned between stay means. The batons are adapted to be mounted to the underside of the truss and are elongate along an axis extending at an angle which is transverse to the longitudinal axis of the truss. The roof sheeting or tile means are located above the truss and the baton means and attached to the baton means by attachment means. Preferably the truss is held a small distance aloft the ground by the baton means, the baton means acting as spacer means for the truss relative to the ground. 
     Preferably the truss is a cable or like flexible member or collection of members and it may be equipped with eyelet or the like means at or adjacent its ends so that the eyelet or like means is able to be engaged by the stay means it is anchored to. It is envisaged however that the tension truss or tension baton of the invention (if it includes tension batons) may be tensioned by gripping its ends and pulling it tight by pulling the ends in opposite directions. But in an alternative arrangement the truss or baton means may be tensioned by stay means along the length of the baton means or truss means so that there is at least one stay means at either end of the truss and at least one stay means tensioning the truss between the stay means at the end of the truss. 
     In another preferred embodiment of the invention the tension truss may be held aloft the ground by at least one spacer means, the spacer means may be in the form of a channel and the roof sheeting or tiles may be attached to the spacer means, the spacer means being elongate along an axis being substantially parallel to the longitudinal axis of the truss. 
     It is preferable in still yet another embodiment of the invention that the cable or like flexible member which forms the truss or baton be coated with at least one layer of protective material such there is a protective skin over at least a portion of the surface of the truss aiding in longevity of the structure. It is intended that the invention be a infrastructure having a very long service life. 
     In all forms of the invention it is preferable the roof sheeting or tile is affixed to the undercarriage without recourse to fastener means which pierce the roof sheeting. It is not however mandatory. In fact it is preferable in some situations that the roof sheeting or tile is affixed to the appropriate members of the undercarriage by piecing fastener means. There may be included spacer means extending between the relative underside surface of the roof sheeting/tile means and the baton means. The spacer means may be an intermediate member or members laying between the sheeting and the baton means preferably. 
     A super catchment facility may include one or more zero height roofs. In an especially preferred embodiment of a super catchment facility there is included at least two zero height roofs being rectangular in shape when viewed in top plan view and being parallel to each other. 
     The zero height roof intercepts rainwater before it may strike the ground and the water catch may require to be stored for later use accordingly we have found that it is preferable to site at least one storage means under the zero height roof for this purpose. Preferably it is positioned below the ground underlying the roof or below the zero height roof. The storage means may require to be accessed by man and or machine and therefore an entrance to it can be made through n created aperture in the roof upper surface or a passage/s can be formed which extends through the soil underlying the roof. We also envisage that a pathway may need to extend to the storage means from a boundary edge of the roof. In some circumstances it may be necessary to build a work space under a small portion or area of the roof, the work space being sunken into the ground. It is also envisaged that the roof may need to be protected from direct engagement with a lightning strike and accordingly the invention may include electrode means extending above the roof to intercept lightning before it can strike the roof proper. Also the roof may need to be grounded to earth for safety reasons. 
     The roof sheeting or tiles used to form the roof may be made of any suitable material. It is a preference that the roof sheeting or tiles be made of metal. It is preferable that they are corrugated sheet. However it is preferred that at least some of the roof sheeting or tiles of the roof are photovoltaic collector means so that the zero height roof is an electricity generating device as well as a water collection system. It is preferable that an embodiment of the invention include photo voltaic collector means, solar thermal collector means as well as function to collect rainwater falling from the sky. 
     Tornadoes, willi-willies and hurricanes are a danger to buildings enclosing air volumes due to pressure differential between that of the air in the enclosed volume and the ultra low localized pressure in the weather phenomenon accordingly the invention may include air outlet means allowing for the rapid evacuation of air from beneath the sheeting or tiles so as they are not subjected to explosive stress and potential roof destruction. There may be included one gate means in the roof surface which can open in response to pressure build up under the roof as required. 
     The tiled dell or ground hollow of the prior art is extremely laborious to make. The tile means formed of rock chips/shards are not mounted on a frame but are overlapingly cascade stacked upon each other relying on friction to hold them in place. The surface created by the shards is not predictably water tight and can fail allowing water to flow under the surface created presenting a considerable problem of erosion and silting of the cistern. The shards may be easily dislodged by earth quake or ground movement and there remains the constant threat of avalanche. The undercarriage of the zero height roof secures its tiles or roof sheeting means in place avoiding this problem. The roof sheeting or tiles in the zero height roof are regular in shape and therefore the labor component of construction on site is less also. 
     It is preferred that the land surface to be clad with the zero height roof system is rectangular and convex in shape. The zero height roof is a very cheap construction method which features the placement of a preferably metal wire or fibre cable grid or net system over the convex arched land surface or mound, at least some of the wire and or fibre are laid out at least generally parallel along the curve of the arc of convexity such that suction forces caused by wind blow-by are carried by the wires and or cables laid out along the arc of convexity are pulled into tension or at least more into tension. The wires and or cables are adapted to be attached to stanchions or stays or pegs at their ends or anywhere practicable an between depending on requirements. The roof sheeting/tile means may be fashioned such that they have surface geometries suitable for mounting and or aligning. Mounting means may be formed from the roof sheeting/tile means material from a roll or sheet or they could be added later if desired. Another preferred embodiment of the zero height roof may be formed such that it is adapted to cover a combination of convex and concave surfaces. Or even straight surfaces can be utilized depending on desire. 
     Generally speaking preferably: with careful selection of sloping lands, easily amenable to terra-forming, having good clean cutting soil structure and high fibre mass ratio the risks and coast can be kept very low. The well formed land surface may be covered with a grid and or cable system onto which may be securely mounted roofing sheeting/tiles means of highly water proof cladding material. 
     A preferred method of implementation of the invention. Select land with nice top soil, loam having a low clay content preferably, the land being slightly sloped or flat, then shape strips of its surface to form arches, have gutters at the arch ends, drape cables or equivalents over the length (convex length) of the arch and tension between stays, place batons over cable truss system and secure to cable trusses, clad over the batons with roof sheeting or tiles and secure such thereon. Preferably the cable truss being protectively coated and allowed to rest on the ground surface or held slightly aloft using riser/spacer means. Site selection is critical but relatively easy. Arch means is best result in relation to anti=lift qualities, plus it is a common and natural land shape. Of course this is a very simple version but the basic idea is there. 
     Generally speaking with regards to the invention unless otherwise excluded the truss is a tension member of the roof sheeting cladding mounting system employed in the invention, however the baton systems used in the invention may also be tension members. Tension and baton members are generally disposed at an angle to each other such that they are at right angles to each other, but, they can be at a more acute or obtuse angle id desired. The trusses are laid out as they are in a house or building and the batons are laid out as they are in a regular setting. The batons are adapted to be attached to ? secured to the tension truss members or an intermediate member or interconnecting means arrangement. In the convex arched version of the device the having tensioned truss means the trusses compress the ground underneath the them. The tension member is tensioned between at least two stay means so that it is tight, preferably. Preferably the tension member or member it engages has location/securement features. Preferably these features are bonded on, or clamped on, or mounted onto the tension member so that they can serve to locate the batons of the system in a desired location relative to the respective truss means. It is preferable that the truss is a strap or laminated structure or woven or knitted or braided or twisted fibre or a wire, cable, rod, bar, pipe channel, beam chain—so long as it is flexible transverse to its longitudinal axis, preferably it is relatively scratch resistant, fire resistant, corrosion resistant. Preferably it is a strap of metal tape or fibre glass fibre or even an extruded structure. 
     The side edges of the zero height roof may be tied down or pinned down. Side tie down pins or pegs can prevent uplift of the side edge of the zero height roof relative to the ground an accordingly can be utilized in all embodiments of the invention if desired. Preferably the tension members which located close to any of the side edges are stronger than those in the roof middle portions so they can assist in extra holding down of the side/s of the roof in high wind events. 
     We often say surface of the ground but we also include in this statement the upper surface of a bladder means if it is substituted for soil as the surface over which the zero eight roof is tensioned or laid out. Furthermore it is envisaged that the surface of the ground may be covered or at least partially covered with at least one layer of material to seal off the ground from the undercarriage of the roof or portion of same and so we include the layer atop the ground for this purpose the surface of the ground. 
     Many small variations of the invention are possible but the variations should not be seen as diminishing the scope and spirit of the invention. It is envisaged that various inventive aspects and integers of the embodiments may be swapped or interchangeable from one embodiment of the invention to another and these will not limit the scope nor damage the spirit of the invention. 
     Like numbers and objects have like meanings and functions and accordingly the drawings and we encourage the reader to mix and match components and integers from the disclose and drawings to any other embodiments of the invention disclosed herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional schematic end view. 
         FIG. 2  is an isometric schematic view. 
         FIG. 3  is a sectional schematic end view. 
         FIG. 4  is an isometric schematic view. 
         FIG. 5  is a sectional schematic end view. 
         FIG. 6  is an isometric schematic view. 
         FIG. 7  is a sectional schematic end view. 
         FIG. 8  is an isometric schematic view. 
         FIG. 9  is a sectional schematic end view. 
         FIG. 10  is a sectional schematic end view. 
         FIG. 11  is a sectional schematic end view. 
         FIG. 12  is a sectional schematic end view. 
         FIG. 13  is a sectional schematic end view. 
         FIG. 14  is a sectional schematic end view. 
         FIG. 15  is a sectional schematic end view. 
         FIGS. 16 ,  17 ,  18 ,  19 ,  20 ,  21 ,  22  are sectional schematic end views. 
         FIGS. 23 and 24  are isometric schematic views. 
         FIG. 25  is a sectional schematic end view. 
         FIG. 26  is an isometric schematic view. 
         FIG. 27  is a sectional schematic end view. 
         FIG. 28  is a sectional side view. 
         FIG. 29  to  FIG. 38  show isometric schematic views. 
         FIG. 39  is sectional end view. 
         FIG. 40  is an isometric view. 
         FIG. 41  is a sectional side view. 
         FIG. 42  is a sectional side view. 
         FIG. 43  is a sectional end view. 
         FIG. 44  is schematic isometric view. 
         FIG. 45  is a section end view 
         FIG. 46  to  FIG. 48  are schematic isometric views. 
         FIGS. 49   a ,  49   b  and  49   c  are schematic isometric views, 
         FIG. 50  is sectional schematic end view. 
         FIG. 51  is a sectional schematic end view. 
         FIG. 52  is a schematic end view. 
         FIG. 53  is sectional schematic end view. 
         FIG. 54  is a schematic isometric view. 
         FIGS. 54   a ,  54   b  and  FIG. 55  are sectional schematic end view. 
         FIG. 55   a  to  FIG. 55   d  are isometric schematic views. 
         FIG. 56  and  FIG. 57  are sectional schematic end views. 
         FIG. 58  is a sectional schematic end view. 
         FIG. 59  is schematic isometric view. 
         FIG. 60  to  FIG. 62  are sectional schematic end views. 
         FIG. 63  is an aerial view of a map. 
         FIGS. 64 ,  65  and  66  are schematic end views. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a sectional end view of a preferred embodiment of a zero height roof system  10  wherein it can be seen that the ground surface  1  is convex arched. A tension truss  2   i  is shown having stay means  3   ai  and  3   bi  and as can be seen the tension truss is in tension over the convex arch. The truss  2   i  is secured at each end  2   ai  and  2   bi  to stay means  3   ai  and  3   bi.  Mounted to the top of the truss can be seen a series of batons  4   a,    4   b,    4   c,    4   d  onto which is adapted to be mounted tile or sheet roofing means  5 . It can be seen that the tension truss is pulled tight over the convex arch. It can be seen there is a small distance between the roof sheeting and the underlying ground  11  surface  1 . It can be seen that there is gutter means  6  provided to catch and direct the flow of water coming of the roof surface  5 . It is preferable that the system include air evacuation means  18  being a flow way or pipe-like means  18  having an inlet and an out let for allowing air to escape from under the roof in case of tornado, willi-willy, hurricane etc. The evacuation means may include fan means for pulling air from under the roof so it does not stale or have dangerous gas build up. The evacuation means can be used to draw of damp air from under the roof thus minimizing condensation build up under the roof  10 . It is preferable that there be included truss hold down means  8  which can assist in holding the truss to the arch surface  1 . The truss hold down means is secured to the truss by securement means  88  and the hold down means is anchored to the ground  11 . It is envisaged that instead of being connected to the ground as shown the hold down means may take the form of a dead weight sufficient to hold the truss down if required. The securement means may be as simple as a wire tie down or be some what more sophisticated. To ensure adequate hydration of the ground under the roof system there may be included at least one small hole in the roof sheeting/tile means allowing water atop the sheeting/tile to pass through onto the surface of the ground underlying the roof. The small hole may if desired connect to pipe means having a diffusion head located below the ground surface so that water passing through the small hole is absorbed into the soil at a distance below the surface and thuswise avoiding scouring of the surface by rivulet of water flowing downhill under the roof system. 
       FIG. 2  shows an schematic isometric view of the embodiment of the zero height roof system  10  shown in  FIG. 1  wherein it can be seen that there are a plurality of trusses  2   i,    2   ii,    22   iii  and, mounted upon them by mounting means (not shown) are baton means  4   a,    4   b,    4   c,    4   d  and onto which are adaptably mounted sheet roofing means or tile means  5 . It can be seen that stay means are located at or adjacent the distal ends of each truss. It can be seen that stay means are located at each end of each truss and that they are secured to the ground  1  such that they are able to resist tension along the longitude of the truss. It can be seen that there is provided a gutter means  6  an end of the roof, the gutter means leading to a cistern (not shown) or into an outlet such that the water may be flowed into a river or dam or consumer/user. 
       FIG. 3  shows a sectional end view of variation of the embodiment of the zero height roof  10  shown in  FIGS. 1 and 2  and in which can be seen spacer/riser means  7   a,   7   b,   7   c,   7   d  holding aloft the ground surface the tension truss  2   i.  It can be seen that the ground  11  has a convex arched surface  1  on which the riser/spacer means  7   a,   7   b,   7   c,   7   d  are mounted. The truss  2   i  is secured to the stay means at each of it ends  2   ai  and  2   aii.  The roof sheeting or tile means  5  is secured to the baton means by securement means (not shown). 
       FIG. 4  is a schematic isometric view of the embodiment of the invention  10  shown in  FIG. 3  in which it can be seen that there are a plurality of tension trusses  2   i,    2   ii,    2   iii  and, that the trusses are secured to stay means.  2   i  being tension between stay means  3   ai  and  3   bi,    2   ii  between  3   aii  and  3   bii,  and,  2   iii  between  3   aiii  and  3   biii.  There is provided a gutter means  6  at the downhill end  43  of the arched roof. The uphill end  44 . Roof sheeting or tile means  5  (not shown) is attached to baton means (not shown) by any suitable method though fastener-less means are preferred. The spacer/riser means  7   a,    7   b,    7   c,    7   d  are situated beneath the trusses such that they hold the trusses aloft the ground  11  surface  1 . Tensioning means (not shown) are employed to set the tension of the trusses against the stay means. The trusses  2   i,    2   ii  and  2   iii  are aligned parallel to each other. It can be seen that the trusses are elongate members and that they are each elongate along a respective axis. The fact that the trusses are pulled around the arched surface of the ground does not mean that the trusses don&#39;t each have a straight elongate axis in use it is just that when they are bent around the arch their elongate axis is bent with the arch. It can be seen that the trusses are parallel to each other and that the baton means are arranged at a transverse angle relative to the trusses they are mounted to. It can be seen that the trusses follow the curve of the arch closely and that there is only a small gap between the roof sheeting/tile means and the surface of the ground over which they extend. 
       FIG. 5  shows a schematic end view of another embodiment of the invention  10  wherein the zero height roof is drawn tight over substantially straight sloped ground  11 . The sloped surface  1  of the ground has uphill end  44  and a down hill end  43 . A tension truss  2   i  can be seen pulled tight between stay means  3   ai  and  3   aii.  Mounted atop the truss  2   i  is a plurality of baton means  4   a,    4   b,    4   c,    4   d.  Atop the baton means is mounted roof sheeting/tile means  5  (not shown). Gutter means may be provide at the down-slope end of the roof system  10 . Note: if the roof is especially long from top to bottom a large amount of water may build up on the roof sheeting/tile means upper surface which could pose a threat to the structural integrity of the sheeting and therefore it is envisaged that gutter means and breaks in the upper surface may need to be included to allow water to be drawn of at a mid-slope portion of the zero height roof system. This solution may be incorporated into all the embodiments of the invention as or if required. The roof sheeting/tile means may extend from top to bottom or alternatively from side to side of the roof It is preferred that the roof sheeting is corrugated steel roof sheeting or of a type which is marketed under the trade name “Clip-Lock”® having means formed with it to secure the sheeting to the baton means without piercing the sheet through with fastener means thus extending the durability of the roof in as much as the lack of piercing hole is a site of corrosion potential avoided. 
       FIG. 6  shows a schematic isometric view of the invention shown in  FIG. 5  wherein it can be seen that a plurality of tension trusses have been drawn tight between stay means across a straight sloped surface surface. The tension truss  2   i  is drawn tight between stay means  3   ai  and  3   bi,    2   ii  is drawn tight between  3   aii  and  3   bii  and, truss  2   iii  is drawn tight between stay means  3   aiii  and stay means 
       FIG. 7  shows a schematic end view of an embodiment of the invention  10  in which can be seen a truss which has been drawn tight into tension over a convex arched ground  11  surface  1 . Furthermore it can be seen that the roof ends are lower than the peak of the arch and that there is situated gutter means  6   a  and  6   b  at respective ends of the roof And that the stay means  3   ai  and  3   aii  are down-slope of the arch peak/crest. And that baton means are disposed periodically along the longitude of the truss  2   i  and are mounted onto the truss  2   i  by mounting means (not shown). 
       FIG. 8  shows a schematic isometric view of the embodiment of the invention  10  shown in  FIG. 7 . It can be seen that the baton means are arranged at a transverse angle relative to the trusses  2   i,    2   ii  and  2   iii.  It is preferable that the transverse angle is 90 degrees. That the trusses extend across the arch and the baton means extend along it. That each of the trusses extends between a pair of stays eg  2   i  extends between  3   ai  and  3   bi.  The embodiment shows a convex arch surface  1  which may be a natural hill or undulation or be man made or may even be formed of a bladder means or plurality of bladder means as required adapted to form a convex arch at least when inflated. 
       FIG. 9  shows an schematic end view of an embodiment of the invention  10  wherein a truss  2   i  has been pulled tight over both a convex arch  1   b  and a concave arch  1   a.  It can be seen that the truss  2   i  has been held down in the concave arch by truss hold down means  8   a,    8   b,    8   c,    8   d  and that the hold down means have each been secured to the truss by respective securement means  88 . It can be seen that the truss  2   i  is attached to stay means at the end of the roof on the convex arch and at uphill of the concave arch. It can be seen that the hold down means are anchored to the ground by anchoring means in the form of a buried length of the hold down means. It can be seen that at least one of the hold down means includes a dead weight  89  to aid in holding the truss  2   i  down. It can be seen that the roof sheeting/tile means covering the concave arch is of two portions and that the roof sheeting/tile means covering the convex arch is formed of one portion. That there is a gutter means  6   i  provided in the bottom of the concave arch for collecting and moving off of water and that there is a gutter means provided for collecting and moving off of water from one side of the roof extending over the convex arch. Basically this is a sectional end view of undulating ground. The undulation may be natural topography or man made. Of course bladder means may be utilized to form the convex arch and or the concave arch if so desired. This is a sectional end view so it cannot be seen that there are a plurality of trusses and baton means and preferably stay means making up the system. Other example of undulating embodiments are included in the drawings of the disclosure and they serve to illustrate what it obvious. It is preferable that the baton means are non-tensioned members of the roof undercarriage. The undercarriage/s of the zero height roof includes all members of the roof structure except for the ground laying below the roof sheeting/tile means. It can also be seen that we have chosen to include riser/spacer means under the baton means to hold the truss aloft the ground surface on the convex arch. The convex arch and concave arch are blended together to form an undulation. The truss extends in a first direction across the arch and the baton means extends in a second direction at a transverse angle relative to the truss longitudinal axis. There is included off-take pipe means  66  connected to the gutter means to assist in decantment of water from the gutter means (this is optional). The roof sections  5   a  and  5   b  may each be formed of respective single lengths of roof sheeting/tile means or at least one of the sections  5   a  or  5   b  may be formed of a cascaded stack of two or more roof sheets/tile means. We show that the stay means is anchored into the ground but this may not be needed in all embodiments of the invention including this one because it is possible to use a dead weight to provide the same function if the mass is enough because the frictional contact between the dead weight and the ground where they make contact is enough to hold the tension existing in the truss  2   i  and its fellows (not shown). It is preferable that the trusses are parallel to each other but this is not always practicable or desirable depending of the site and structural needs of the system. It is preferable that the batons are elongate along an axis which is at right angles to the longitudinal axis of each of the trusses. It is preferable that each of the trusses is tensioned between a pair of stay means. The stay means  3   a  includes through hole means  37   i  through which passes the threaded end of truss  2   ai  whereupon it is engaged by tensioning means in the form of a threaded nut  34   i  which is tightened against an outside surface  39   i  of the stay means  3   ai.    36   ii  is an inside surface of stay means  3   bi.  The outer surface of the stay means faces away from the tension load in the truss inline with the longitudinal axis of the truss  2   i.  The concave portion of the roof is in effect a suspended portion of the roof and the convex portion is a compression portion of the roof That is the convex portion is pulled down over the arch and the concave is suspended above or to the surface of the ground of the concave arch surface of the ground. It is a combination suspension compression roof structure. 
       FIG. 10  shows another embodiment of the zero height roof system  10  in which can be seen a zero height roof extending around a concave arched ground surface  1 . The zero height roof in this embodiment is of course concave shaped also because it follows the arch it covers being a concave arch. It can be seen that truss hold down means are included which hold the truss so that it tracks the surface of the arch. The tracking need not be absolute as can be seen because the hold down means holds the truss down at a height above the surface of the arch. Fact is the underlying ground in the concave versions of the roof need not be arched if the hold down means are of lengths which conform the truss to form an concave arch. The cable can be tensioned to pull it hard against the surface of the ground or onto bearer baton system (riser/spacer means) laid out periodically on the surface. The tension of the tension members may be preset or may be dynamically tensioned so that the tension member can cope by way of adjustment with thermal expansion forces, stretch of tension member or even wind conditions if required. 
       FIG. 11  shows an sectional schematic end view of an embodiment of the zero height roof system  10  wherein the roof is of a convex arch shape being tensioned over an convex arch surface  1  and wherein can be seen that there is provided a number of roof sheets/tile means  5   a,    5   b,    5   c  mounted atop baton means  4   a,    4   b,    4   c,  and  4   d.  It can be seen that a cistern  600  has been mounted below the roof structure in order to store water without taking up additional land area. The cistern is connected by pipe means  66  to gutter means  6  stationed at down hill end of roof. The water level  605  can be seen. Water outlet  601  from the cistern is shown connecting cistern to pump means for rapid evacuation of the cistern. Stay means  3   ai  and  3   bi  are stationed at respective ends of the roof and tension member means  2   i  is drawn tight between them. Roof sheets/tiles  5   a.    5   b,    5   c  are mounted atop the baton means  4   a,    4   b,    4   c,    4   d  and are secured to the baton means by securement means  55   a,    55   b,    55   c,    55   d.  The securement means in this case being fasteners which pierce the sheets to hold them onto the baton means. Tension means  34   i  and  34   ii  being threaded tensioning means engaging threaded ends of the truss  2   ai  and  2   bii.  The baton means extending at 90 relative to the longitude of the truss means  2   i.  the drawing shows that at least one water storage may be positioned under the roof structure to save space. The surface over which the truss is drawn tight is a convex surface. 
       FIG. 12  shows an schematic end view of an embodiment of the zero height roof  10  wherein can be seen a cistern  600  connected to gutter means  6  by pipe means  66  and the cistern being equipped with at least one outlet pipe  601  means including pump means  605  or feeding water  604  under pressure via pipe means  607  into the soil  11  underlying the zero height roof so that stored water may be added to the soil in order that it not shrink due to water starvation, the water entering the ground via diffusion/discharge means  608   a,    608   b  and  608   c.  It can be seen the zero height roof system includes stay means sited at each end of the roof system and that tension truss  2   i  is extended between them. The surface of the ground over which the truss  2   i  extends is straight but sloped so that there is an uphill end of the roof system and a downhill end. The down hill in including gutter means  6 . The truss being held aloft the surface  1  a small distance by riser/spacer means  7   a,    7   b,    7   c,    7   d  which rest upon the ground and each engaging athe or a respective underside surface of the truss. The truss is tensioned by tensioning means which in this case are threaded tensioning means  34   i  and  34   ii.  The truss ends  2   ai  and  2   bi  adapted to engage by threading with the tension means. As can be seen the baton means are overlaid with roof sheeting/tile means  5   a,    5   b,  and  5   c  which are secured to the baton means by securement means  55   a,    55   b,    55   c,    55   d.  Truss hold down means  8  are included as an option. The baton means extending at right angles preferably relative to the truss length although other orientations are contemplated including greater than 90 degrees. 
       FIG. 13  shows an schematic sectional end view of the zero height roof  10  wherein is included air evacuation means in the form of a gate or door  555  being a hinged gate system able to swing on hinge  555   a.  As can be seen a tornado, willi-willy, hurricane  15  is shown. The localized low pressure system posing a threat to the integrity of the roof if pressure build up is too great and too rapid due the weather phenomena. The direction of air flow is shown  17  escaping the air vent means  555 . The truss  2   i  being secured to the stay means  3   a  by holding means in the form of a hook  23  and ring  33  arrangement. The ring being mounted to or formed with the stay means and the hook being part of or otherwise connected to the truss end  2   ai.  The truss at its down hill end being engaged by tension means  34   ii  being threaded tension means although any suitable tensioning method may be utilized. The roof sheeting/tile means  5  being held aloft the baton means  4   a,    4   b,    4   c,    4   d  by spacer means  44   a,    44   b,    44   c,    44   d.  the truss  2   i  being tensioned between stay means  3   ai  and  3   bi  and the system being a sloped system having an uphill end and a down hill end. The truss being a small distance from the ground. The small distance may be as little as zero. 
       FIG. 14  shows a schematic sectional end view of an embodiment of the zero height roof  10  wherein the small distance  99  can be seen extending between the surface  1  over which the truss  2   i  is tightened. It can be seen the truss end  2   ai  extending through hole means  37  in stay means  3   ai  and that the end  2   ai  of the truss means  2   i  is threaded and engaged by tensioning means  34   i.  The threaded tensioner tensioning against an outside surface  301  of the stay means  3   ai  via washer spacer means  300 . 
       FIG. 15  shows a tension member being in this case a truss  2   i  tensioned between stay mean  3   ai  and  3   bi  by turnbuckle means  344   i  and  344   ii.  There being a threaded member  3444   i  and  3444   ii  between the stay means and the turnbuckle means. Baton means may be similarly tensioned if required in a tensioned baton version of the zero height roof  10 . 
       FIGS. 16 ,  17  and  18  show three different embodiments of the invention  10   FIG. 16  being a convex form of the system,  FIG. 17  being a straight sloped verion of the invention and Figure showing a concave and straight (skillion) combination version of the invention wherein at the juncture of the straight and curved (arched) portions is included stay means  3   ci  being combined stay hold down means for holding the tension member being in this case a tension truss member into the hollow formed at the juncture. All three version being tension truss versions of the invention wherein the tension truss  2   i  is tensioned between stay means. Preferably the tension force is more than zero. 
       FIGS. 19 and 20  show schematic sectional end views of the invention  10  wherein the overlaying roof sheeting/tile means are not shown for clarity.  FIG. 19  showing a tensioned truss concave arch arrangement and  FIG. 20  showing a gable arrangement. Each of the truss  2   i  systems is tensioned between stay means. The gable version including stay means for each side of the gable both uphill and down hill. The gable is at an angle to a bisector  4000  as indicated by angle A and angle B. The  FIG. 20  is in effect two skillion roofs aligned back to back at the crest of the gable. 
       FIG. 21  shows a schematic sectional end view of a preferred undercarriage of the invention. The system including tension member means being in this case a tension to truss member being tensioned by tension means being rotary tension member means in the form of a ratchet and pall arrangement driven by hand crank. However machine means or machine driven means may be substituted for hand crank if desired. 
       FIG. 22  shows a schematic sectional end view of an embodiment of the invention wherein the underlying ground surface has been formed into a rough convex arch formed of a series of flats  1   a,    1   b  and  1   c.  There being an included angle between each flat as shown by angle A and angle B. The ground  11  may be in some circumstances easier to form into an arch if flats are used instead of a continuous curved surface. This solution may be adopted by any of the embodiments of the invention utilizing arched ground surfaces. Also of note is that there is included at least one stay means  3   bi  located inboard of the end of the roof structure and that in this embodiment we have included riser/spacer means to hold aloft the truss means from the flatted surface of the ground. The roof sheeting/tile means  5  being adapted to be mounted upon baton means  4   ai,    4   bi,    4   ci,    4   di  adapted to be mounted to the truss means  2   i.    
       FIG. 23  shows an schematic isometric view of an embodiment of the invention in in an inverted Vee configuration (inverted gable) having stay means  3   ci,    3   cii  and  3   ciii  in the corner of the Vee. Tension trusses extending from one side of the Vee to the other and tensioned between stay means  3   ai,    3   cii,    3   aiii  and  3   bi,    3   bii  and  3   biii  respectively. The stay means  3   ci,    3   cii  and  3   ciii  being secured to the gutter means formed in the base or corner of the Vee. Baton means  4   ai,    4   bi,    4   ci,    4   ei,    4   fi  being mounted to the truss means such that roof sheeting/tile means may be mounted onto the under carriage of the zero height roof system  10 . 
       FIG. 24  shows a schematic isometric view of an embodiment of the invention being in the form of an inverted hip. 
       FIG. 25  shows an sectional end view of undulating land surfaces  1  covered with the zero height roof system  10  undercarriage. 
       FIG. 26  shows a schematic isometric view of an embodiment of the invention featuring tension baton means  4   ai,    4   aii,    4   aii  mounted onto tension truss means  2   i,    2   ii,    2   iii,    2   iiii  of the invention. The trusses are tensioned between stay means as shown and the batons are tensioned between baton stay means  33   ai,    33   aii,    33   aiii,  and  33   bi,    33   bii,    33   biii  respectively. Roof sheeting/tile means (not shown) are mounted to the baton means or an intermediate spacer means attached to the tension trusses. The baton means are preferable arranged in a perpendicular direction relative to the underlying truss means as depicted in angle A. The embodiment show a sloped zero height roof arrangement but it can be readily seen that the same solution can be introduced into many of the embodiments of the invention disclosed herein for a non-limiting example consider the convex arch version or concave arched versions of the invention. The trusses and baton means are preferably flexible in directions transverse to their respective axis and preferably substantially inflexible in directions parallel to their respective axis. Optionally truss hold down means  8  may be included. Optionally baton hold down means  08  may be added functioning in the same way as truss hold down means operates. The baton hold down means including securement means  088  for engaging the respective baton as in the case for truss hold down means. 
       FIG. 27  shows a schematic end view of an embodiment of the zero height roof system being tensioned over a pair of convex arched surfaces of ground  1   i  and  1   ii.  A tension truss  2   i  can be seen extending between stay means  3   ai  and  3   bi  passing enroute stay means  3   ci  to which is secured a middle portion of the truss means  2   i.  A spill tray gutter means  6  is attached to the truss means and is suspended on the truss means above the surface of the ground  11 . The stay means  3   ci  is located below the truss means  21  and below the spill tray/gutter means. The baton means  4   ai.    4   aii.    4   aiii,    4   aiii  and  4   bi,    4   bii,    4   biii,    4   biiii  are mounted atop the truss and secured to the truss  2   i  by securement means. Mounted to the baton means are roof sheets/tile means although it is preferable to include at least one small riser/spacer means between at least one of the roof sheets/tile means and a respective baton means. The system is formed in a ground hollow or dell. Riser/spacer means may also be included between the truss and the ground if desired. The baton means may be tensioned baton means or not as required. The spill tray/gutter means could alternatively be mounted upon the baton means if required whether the baton means be a tension baton means or not as required. The spill tray/gutter means is secured to the tension member by securement means which may be as simple a wire tied knot if desired. There is a small gap between the roof sheeting/tile means and the ground. As can be seen there is more than one roof sheet used to cover the width of the arch on each side (A or B) of the roof. In this embodiment the truss is held in the hollow  6000  by the stay means  3   ci  which serves as a truss hold down means as shown. The there is free space between the truss and the hollow floor  6001 . The free space can be as little as zero. It can be seen that the system includes a first convex arched portion  1   i  located on a first side of the ground hollow or dell and a second convex arched potion on a second convex arched side of the ground hollow or dell. The roof sheeting/tile means are preferably cascade stacked as shown. By cascade stacked we means that they overlap such that the upper hill roof sheet/tile means over laps its adjacent lower roof sheet/tile means. The tensioning means may be associated with any of the following as required: the ends of the truss means  2   ai  or  2   aii,  or a middle/intermediate length of the truss mean  2   i.  The stay means  3   ci  may be associated with the stay means  3   ci  and pull the tension member  2   i  down into the hollow. The stay means  3   ci  could if preferred be a dead weight. Preferably however the stay means  3   ci  includes tensioning means able to pull the truss  2   i  down into the hollow and hold it there. The tensioning means may be a turnbuckle arrangement having a first connection or interconnection with the truss and second connection or interconnection with the stay means  3   ci.  More than one stay means may be situated in the floor of the hollow if required. to pull and hold down the truss means into the hollow. The batons as with all the embodiments of the invention may be tension baton means tensioned between baton stay means if desired. 
       FIG. 28  shows a sectional schematic side view of a hydraulic tensioning system  2600  which may be utilized in embodiments of the invention  10  to maintain or adjust the tension of a tension member  2   i  of the zero height roof The hydraulic tensioning means including a power piston  266  for pulling the tension member (preferably a tensionable cable  2   i  tight. The power piston being driven by fluid pressure means (not Shown). The power piston adapted to be connected to a tension cable  2   i.  The power piston including engagement means  264  to engage the tension cable or member. A cylinder body  267  of the power piston system adapted to be connected to stay means (not shown). The hydraulic tensioning means may be controlled remotely use hydraulic means or electromechanical means or, it may be operated by hand adjustment of pressure valve means (not shown). 
       FIG. 29  shows a isometric view of a tension member being a rope or cable means  250  of the invention. The tension member being elongate along an axis  2511 . 
       FIG. 30  shows a tension member being a cable means including a locator and or alignment means formed on the cable. The elongate axis of the member is shown  2511 . preferably the locator and or alignment member is swaged on or welded on or bonded on but may be attached to the elongate member by any suitable means. It may be melted onto the tension member, sintered on or formed from the tension member of tension member material. 
       FIG. 31  shows a solid wire tension member cable means  250  of the invention. The elongate axis of the member is shown  2511 . 
       FIG. 32  shows a linked tension member  250  being elongate along an axis  2511 . The linked tension member being a chain or the like. The chain tension member including at least two links  2599   a,    2599   b,    2599   c,    2599   d,    2599   e    
       FIG. 33  shows a strap-like tension member  250  being elongate along an axis  2511 . The tension member is elongate along an axis and has a first end and a second end. 
       FIG. 34  shows a laminated tension member  250  being elongate along an axis  2511 . The laminated tension member including several layers of material bonded or other wise formed together members to form a tension member. Preferably there are two or more laminations  258   a,    258   b,    258   c.  Tension members may be trusses or baton means as desired. 
       FIG. 35  shows a roof sheet/tile means  5  in isometric view. It is a pan type sheet tile means. 
       FIG. 36  shows a roof sheet/tile means  5  being corrugated metal sheeting. As can be seen it is preferable that the roof sheeting be arranged such that the length of the roof is in the direction of A and the width of the roof extends in direction B relative to the longitudinal axis  50  of the roof sheeting/tile means. 
       FIG. 37  shows an isometric view of a roofing sheet  5  of the invention being a flat pan type member. 
       FIG. 38  shows a combination deep pan corrugated roof sheet/tile means  5  of the invention. Generally speaking the roof sheeting/tile means used in the invention may be made of any suitable material desired. Axis of roof sheet/tile means is preferably aligned parallel to the longitudinal axis of the truss means of the zero height roof. This need not be so however as the axis may be aligned at an angle to the axis of the truss. 
       FIG. 39  shows a sectional end view of a tension truss means. The tension truss means  2   i  includes locating means  255  for engagement with surface/s of baton means. The tension truss is elongate along an axis. 
       FIG. 40  shows a tension member in isometric view and being a truss member in this instance being elongate along an axis as shown and having securement feature means in the form of a locator lug for engagement with surfaces associated with a baton means and or riser/spacer system. Be that a spacer riser system for holding the truss aloft the ground or a spacer means for setting a distance from the truss to a baton means of the invention. Tension Member, being preferably a cable, wire, rope, or strap. 
       FIG. 41  shows a side view of the truss means depicted in  FIG. 40  incorporating locator lug means for locating the baton means in a suitable location along the length of the truss means and relative to the longitudinal axis of the truss. 
       FIG. 42  shows a side view of the truss depicte in  FIG. 40 . It can be seen that the truss is elongate along an axis being its longitudinal axis. 
       FIG. 43  shows a end view of the truss means and as can be seen the truss has a locating lug. The locating lug is triangular. The baton means is attached to the locator lug means by an attachment flange and trap means. Elongate along an Axis. Fastener System, Glue, Bonding Medium, Weld, Swag, Metal Tab. Locator Feature or Hole or Lug in Clamp Flange engaging corresponding feature of Tension Member. 
       FIG. 44  shows an isometric view of the tension truss mean  2   i  having locator lug  222   
       FIG. 45  shows an end view of the tension truss  2   i  having at least one locator lug  22  trapped in the enclosure formed by the clamp flange means. The clamp flange means being a unit attached to the baton means by a fastening arrangement including fastener means. A Flange of Clamp Flange. The Clamp Flange is in the form of a Enclosure or Trap for Trapping the Locator in. 
       FIG. 46  is an isometric view of a tension truss means  2   i  having a locator lug means. At least one locator lug or feature located on tension member. 
       FIG. 47  is an isometric view of a tension truss or baton means having a locator lug means. The fastening system formed or mounted on the locator lug is for bolting a member of the roof undercarriage to and or for bolting the sheet/tile means to. Fastening system mounted on locator feature could be rivet post or weld post. 
       FIG. 48  is an isometric view of a tension truss or baton means having a locator lug means. Fastener and or Locator System. 
       FIGS. 49   a ,  49   b  and  49   c  are schematic isometric views of the invention  10  as it is being erected. As can be seen the zero height roof is pulled tight around a convex arch. 
       FIG. 50  shows a sectional end view of an embodiment of the invention which includes automatic adjustment of tension in the truss by using hydraulic ram means which are also truss hold down means. The truss  2   i  is held at its ends by power piston means which are acted upon by chamber means to alter the tension of the truss means over the arches  1   a  and  1   b.  Stay means are hydraulic piston means. Surface  1   a  an  1   b  are convex arched strips of land covered with the invention. The outer stay means are also tensioning means for the truss  2   i.    
       FIG. 51  shows a cascade of roofing sheets/tile means  5   a,    5   b,    5   c,    5   d,    5   e.  It can be seen that the upper sheet overlaps the lower sheet and so on. Note how the upper sheets overlap the lower adjacent sheet. 
     
       FIG. 52 
     
       FIG. 53  is a sectional schematic end view of an embodiment of the zero height roof  10  which includes sheath means for sheathing the truss means in a protective layer and to allow the truss to be held aloft the surface of the arch it is tensioned over, The sheath means  2111  including a through hole through which the truss  2   i  is locate.  FIG. 53  is a sectional schematic end view of an embodiment of the invention  10  wherein is included a sheath system for sheathing the tension truss  2   i  so as it is protected from the environment and/or so the tension truss may be held aloft the ground surface. The tension truss is elongate along an axis and the sheath segments each have an elongate through hole through which extends the truss parallel (axially) to the longitudinal axis of the truss means. The system as depicted in  FIG. 53  is an convex arch Zero Height Roof of the invention wherein the truss means is/are pulled tight between stay means,  34   a  and  34   b.    
       FIG. 54  shows an isometric view of the sheath system utilized in  FIG. 53  and it can be seen that the sheaths  2111   a  and  2111   b  have through hole mean allowing the truss to be inside it. The sheath has a wall thickness which establishes the distance the truss is held aloft the ground. A Riser Sheath is situated over the Tension Truss to hold it of the ground. 
       FIG. 54   a  is sectional schematic end view of an embodiment of the invention  10  including spring type riser/spacer means  7   a,    7   b,    7   d  holding the truss  2   i  aloft the surface of the ground/arch  1  over which the roof is tensioned. The riser/spacer means may be sprung or formed of spring material. The spring function of the riser/spacer system used as a self regulating tension adjustment system for the tension truss means. 
       FIG. 54   b  is is a sectional schematic end view of an embodiment of the invention  10  wherein is can be seen that the riser spacer means holding the truss  2   i  aloft the ground are pipe baton means allowing water to be piped around the roof whilst saving space. Riser/spacer means for holding the truss aloft the ground surface/surface of arch. The riser/spacer system maybe a pipe through which water may be piped. 
       FIG. 55  is a sectional schematic end view of an embodiment of the invention which includes spring type riser/spacer means  7   a,    7   b,    7   c,    7   d  for holding aloft the truss means  2   i  from the surface of the arch over which the zero height roof is tensioned. Hole allowing a small percentage of rain or dew to make its way to the ground. Ground surface, formed surface, preferably arched or preferably having the cable arched, or having the cable tensioned around an arched, (including multi-segment tension members) 
       FIG. 55   a  is an isometric view of a roof sheet/tile of the invention which includes a small hole through its upper surface leading through to its lower surface for allowing a small amount of water through so that the water so let through may act to re-hydrate the underlying soil. Preferably at least one of the roof sheets/tile means cladding the batons of the invention includes a hole for this purpose. Hole in Tile Sheet or through cladding layer allowing water flow through a portion of the tile sheet thuswise allowing water to reach the ground underlying the cladding and thereby avoiding ground shrink back resulting in structural failure. 
       FIG. 55   b  shows a spring like riser/spacer means for holding the truss aloft the surface of the arch a small distance in an un-sprung compression height. The spring riser spacer means and compression springs. Concertina folded spring or rigid riser system. 
       FIG. 55   c  shows a sectional end view of a spring riser/spacer means in an un-sprung position. Note: un-sprung height A. 
       FIG. 55   d  shows the spring riser means of  FIG. 55   c  in a sprung position. Please note distance B is less than distance A in  55   c.    
       FIG. 56  shows an embodiment of the invention  10  wherein the truss is held aloft by rollerised bearing riser/spacer means adapted to allow the truss to move along a bearing pad as the roof shrinks and expands with thermal excitation. Sloped ground preferably. Bearing pad along which the roller may roll allowing the roof to move across the arch. 
       FIG. 57  shows an embodiment of the invention  10  wherein is included riser/spacer means which include sliding bearing surfaces  102  or allowing the truss  2   i  to move both in line with its longitudinal axis and or transverse to it if desired. Sliding bearing means of pad or ground along which the riser/spacer means may move. Preferably the movement is in line with the longitudinal axis of the truss means. Riser/spacer means having a sliding bearing lower surface for sliding engagement with sliding bearing pad located on ground so as the riser/spacer means holding the truss aloft can move both in line with the longitudinal axis of the tension truss means and transversely to said axis also if required for erection of roof purposes and or accommodate thermal expansion of roof structure. 
       FIG. 58  bladder means can be used to form the surface over which the tension members are tightened. 
       FIG. 59  the bladder means are located under the net or grid formed by the tension member system forming the undercarriage of the roof. Preferably by a “small distance” we mean less than 1 metre and preferably less than 500 mm above the ground or arched surface. It may be greater in some embodiments. 
       FIG. 60  shows a bladder means for forming an arch overwhich the tension embers forming the roof are to be tightened. One should note that the lower surface of bladder means may be the ground or may be a complete bladder having an upper and lower surface. Actual surface of ground lies beneath the lower surface of the bladder means. 
       FIG. 61 . shows the bladder means of  FIG. 60  in a pumped up state before the tension members are overlaid it. Air inlet tract/outlet tract for inflating the bladder means, the inlet or outlet tract may allow air/liquid or solids entry to bladder. Upper surface of bladder means is flexible. 
       FIG. 62  shows how the bladder means used in the zero height roof may be filled with solid matter or matter which sets hard inside the bladder means. The bladder means has un upper surface  1  and rests upon the ground over which the tension members are over laid of the zero height roof utilizing said balder means. The bladder means may be held down additionally with hold down pins secured to the ground if desired. Internal volume of bladder may be filled with gas, fluid, solids or any combination of same. Solids filled bladder if desired may be surf board foam, balls, vermiculite or any other filling agent. Preferably the filling agent sets into a solid when the bladder has been properly inflated. Bladder tie down means are included to hold the bladder to the ground and or to attach tension means to. On this page can be seen 3 images of a bladder means in the process of inflation and the process starts at the top drawing on page with the finished outcome being the lowest image on the page. as can be seen a bladder means may be used to form the surface and indeed underlying structure on which the roof system is erected. 
       FIG. 63  shows a map of warragamba dam and a preferred location zone for the zero height roof system.