BACKGROUND OF THE INVENTION There are a number of typical scenarios in which building structures need drying. Many cementitious compositions are used in the building industry by mixing them with an appropriate quantity of water for hardening as well as for convenient application. For example, a screed is a relatively thin porous layer of cementitious composition of about 90% sand and about 10% Portland cement which is applied to a floor structure, e. g. a cast concrete floor, to level it prior to applying the finishing wooden floor or carpet. In all such cases, especially screed, concrete slab and fireproofing insulation, excess water (beyond what is necessary for hardening) takes a long time to dry, significantly delaying the completion of the building work. Accelerating the drying of screed with furnaces or blowers should be avoided because it may result in cracking and warping of the screed. In many cases, for example when the construction times are critical and the weather is cold and damp, waiting for building structures to dry adequately can be highly inconvenient, and have substantial adverse economic consequences.

A second scenario arises in the case of building structures becoming wet and subject to water damage e. g. as a result of flooding or water leakage from pipes or through faulty structure waterproofing, whether from water penetration from outside the building, for example, rain or flood, or inside the building, for example, due to a burst water pipe. In these cases, drying is required as soon as possible to prevent and repair structural and aesthetic damage as well as to reduce adventitious mould and fungi growth that may have adverse health effects.

Inter alia, two particular building structures are susceptible to incurring substantial economic loss due to damage in case they become wet.

The first of the above-mentioned structures relates to wooden floors, whether constructed of planks or of blocks such as parquet flooring, for example.

If these structures are subjected to excessive wetness, rapid and effective drying is required to prevent too much water penetration into the interior of the individual pieces of wood which would lead to staining, swelling and distortion and, in severe cases, to the necessity of scrapping and replacing the entire floor.

The second of the above-mentioned structures relates to tile floors, whether constructed of, for example, polished natural stone, or of ceramic or terrazzo tiles, that are laid with mortar or other bonding agents on a porous layer comprising sand, screed, insulation or another porous aggregate. The porous layer is usually enclosed between the structural concrete slab underneath it, the tiles and mortar on top of it and the walls on the sides. When the porous layer becomes wet it can absorb huge quantities of water. For example, a layer of sand 10 cm. thick may absorb 27 litres of water per square meter. Due to capillary ingress of water, wet porous layer underneath the tiles typically results in significant staining of the tiles, damage to the plaster and paint in the lower parts of the walls, and swelling and staining of wooden doorframes. Mould, fungi and foul smell may also develop in these wetted structures. However, a more significant problem lies in that the water is locked in the porous layer that is enclosed from all its sides and may take many years to dry naturally.

Furthermore, all of the currently known drying methods are ineffective when trying to dry this porous layer. The only effective solution known to such wet porous layer is to remove all the tiles, dry or replace the wet porous layer with a dry one, and resurface with new tiles. This solution is very expensive and inconvenient and usually requires the inhabitants to move out of the building for the duration of the replacement work.

A special case is the combination of the above two cases: a wooden floor laid on top of a tile floor that is laid on a porous layer, for example, sand. When the porous layer becomes wet, capillary as well as water vapor ingress leads to swelling and staining of the wood, and to failing of the bonding that result in disintegration of the wooden floor. The only effective solution known in the art for such a case is to remove the wooden floor as well as the tiles, to dry or replace the wet porous layer with a dry one, and resurface with new tiles and new wooden floor. This solution is even more expensive and inconvenient than that of the previous cases.

It is widely known that the rapidity with which any material dries depends on a number of factors, most importantly the relative humidity and the temperature of the surrounding atmosphere. The rate of evaporation generally depends on the difference between the vapor pressure of the water in the material to be dried (which, in turn, depends on its temperature) and the partial pressure of water vapor in the atmosphere. It is accordingly well-known to assist drying by the use of plant designed to change the conditions locally of the structure concerned. Thus, it is common practice in building construction to employ blowers or portable heating units to blow unsaturated hot air into rooms, for example, with a view to drying building parts faster. It is also known to improve drying by local dehumidification, for example by inducing a flow of dehumidified air over a building structure so that, on its passage over the building structure, it picks up more moisture from the materials of the building structure than ambient air does.

Neither of these approaches, both of which are energy intensive and inefficient, produces as much improvement in drying times as desired in many cases of wooden floors, and they are totally ineffective in the case of tile floors laid on a porous layer such as sand. They should not, in any case, be applied to screeds because they may result in cracking and warping of the screed.

Another drying technique operates on the principle that the rate of evaporation of water (or, indeed, other volatile material) is materially enhanced as the pressure is reduced. Indeed, if the pressure is reduced below the vapor pressure at a given temperature (even ambient temperature), the liquid boils with a consequent very substantial increase in the rate of evaporation, i. e. the rate of drying. It is well-established that even without reaching the boiling point, the rate of liquid removal from materials by evaporation grows as the pressure of the atmosphere around those materials is reduced, for example by the application of suction or a vacuum.

Such techniques have, however, traditionally been used in the chemical industry using heavy, thick-wall vacuum chambers constructed of steel, into which the wet material is loaded, the door is closed and sealed, vacuum applied, and after drying the vacuum is released, the door opened and the dried material unloaded. Such fixed plant and equipment is wholly impractical when attempting to dry fixed building structures, such as floors, for example. In JP2002-079504, RU2206843 and CN1090922, similar types of drying equipment are disclosed, used for drying lumber including wood boards that are not yet installed in a building structure.

In JP8-218568, a method is disclosed for the forced drying of a ground concrete slab. A groove is built into the concrete slab and sealed above with a metal structure, and a vacuum is applied in the cavity thus formed. The groove and the metal structure remain embedded in the concrete. It is totally impossible to use the method on a finished structure, without first having formed the grooves therein.

GB 1018664 is specifically directed to the drying of roof structures, in which the waterproofing and the insulation on the roof need to be cut in order to install an air circulation circuit including a groove, and the waterproofing layer has to be re-sealed afterwards over the circulation groove. According to this publication, the same air is re-circulated repeatedly after being cooled for removing moisture at a condensing station. This results in an extremely slow drying rate that is not practical to use, as the flow rate of the dry air must generally be maintained low to avoid rupturing the enclosure of the dry air circulating system. The method is not suitable for floors and the like, and if applied thereto would require special groves or channels to be formed in advance when constructing the floor structure.

GB 1128166 is also directed to the drying of roofs. In one embodiment, discrete and permanent perforated tubes are built into the concrete during the construction of the roof. In another embodiment, a rubber suction cap is overlaid over a hole in a membrane that covers the roof. In yet another embodiment, a membrane is temporarily fitted over an underlying layer of porous mesh, and tubes are fixed to the membrane. In each case, a suction pump is connected to the tubes or the cap. However, the arrangements disclosed are ineffective in drying the roof structure, and at best only perform to some degree in the vicinity of the perforated pipes.

One of the reasons why the above methods fail to provide effective drying is that they do not take into account the fact that building structures are never airtight. These methods fail to recognise, much less cope with, the significant ingress of ambient air drawn into the structure when a vacuum is applied, thereby nullifying their effect.

SUMMARY OF THE INVENTION The present invention is directed to a system for drying a building structure, such as for example a floor, an underfloor layer, or the like, and in particular to a channeling arrangement useful for drying such structures, wherein the arrangement is preferably portable, reusable, and temporarily overlayable over the structure to be dried. The channeling arrangement comprises at least one cavity forming spacing element, typically in the form of a network of channels, sealingly overlayable over said structure to limit the ingress of ambient air that does not flow through the wet structure when suction is applied. It is adapted for connection with a suitable suction source to provide fluid communication therewith, such as to enable air, water and water vapor to be extracted from the said structure via said channels. The system comprises the aforesaid arrangement, and further comprises a suitable suction source, such as for example a suitable suction pump, in fluid communication with said network.

In the described embodiments, the network of channels comprises a plurality of channeling members, each said member comprising an open bottom end and a wall displaced from said end defining a said channel, and at least one side opening adapted for connection at least to other said members. At least one said member comprises an inlet port sealably joinable to a conduit in fluid communication with said source. The members are preferably modular and are connectable to other said members via said side openings or end openings in any desired combination or permutation. The members typically comprise any one of : longitudinal members, elbow members, T-members, cross-members, end members. A plug member may also be provided for closing a said side or end openings.

Each channeling member is substantially semi-cylindrical in form, and may comprise a transverse cross-section that is any one semi-circular, arcuate, rectangular, semi-hexagonal or polygonal, for example, the transverse cross- section typically comprising an area of between about 5 cm2 and about 100 cm2, preferably between about 9 cm2 and about 40 cm2, but may be smaller than 5 cm2 or larger than 100 cm2'.

The system is very portable, as it can be separated out into the modular components, and assembled on site as required. It is also reusable, since it may be disassembled and reassembled as often as required, and if components break or become unusable, they may be replaced as required.

In a first embodiment, the channeling arrangement comprises a substantially impermeable membrane overlaying said network and sealingly joined to said suction port, said membrane being adapted for being sealingly abutted onto said structure such as to sealingly overlay said network over said structure. The membrane typically comprises a suitable plastic film or a rubber sheet with low permeability to air and to water vapor. The members may be made from any one or combination of plastic, metal, wood or composite materials, and may be permeable or impermeable. Further, adjacent said members are joined one to another at corresponding said side openings-by overlapping, abutting the ends of the members having said side openings, for example, and the members are held in place by gravity and do not need to be attached to one another or to the floor. The arrangement may optionally further comprise at least one intermediate layer between said membrane and said network. This intermediate layer typically comprises a suitable porous material, optionally including any one or combination of woven fabrics or non-woven mats, optionally made of fibreglass, polyester, polyamide, polypropylene, jute, cotton, or any other suitable material. In this embodiment, the periphery of said membrane is salable with respect to said structure by means of any one of or combination of sealing tapes, adhesive tapes, flexible seals, setting suitable weights along the said periphery, adhesive or solvent bonding or mechanical clamping, and so on. In his embodiment, the membrane seals the whole system.

In a second embodiment, the members are substantially impermeable, and the said members are adapted for being sealably abutted, directly or indirectly, with respect to said structure at said bottom end of the members. The inlet suction port is sealingly mounted onto a said member typically integrally therewith. Further, adjacent said members are sealingly joined one to another at corresponding said side openings-by overlapping, abutting the ends of the members having said side openings, for example-typically by means of any one of or combination of sealing tapes, adhesive tapes, flexible seals, adhesive or solvent bonding or mechanical clamping. Optionally, the members comprise a suitable skirt. The members are sealably abutted onto said structure typically by means of such as sealing tapes, adhesive tapes, flexible seals, setting suitable weights on said members, adhesive or solvent bonding or mechanical clamping.

The cavity forming spacing elements may have different forms. For example, a panel (comprising an inlet suction port for connection to the suction source) having on the lower side thereof a plurality of webs and optionally side walls, all of which abut the structure to be dried, forming cavities through which air, water, vapors and so on can flow from the structure towards the suction source. In fact, it is also possible to do away with the webs, and provide spacer elements, for example blocks or the like, at the underside of the panel, and when coupled with a membrane operates in a similar manner to the channeling members. Similarly, the cavity forming elements can be in the form of an open box-like configuration, having the opening facing downwards towards the structure to be dried. This configuration, which includes an inlet port for connection to the suction source, provides a plenum in which air, water, vapors and so on can collect and flow from the structure towards the suction source.

The present invention is also directed at a method for drying a building structure, such as a floor, underfloor layer, or the like, for example, comprising sealingly overlying an arrangement including at least one cavity forming spacing element typically in the form of a network of channels, on said structure and applying a suction to said channels from an external source with respect to said network to reduce the air pressure within the channels.

Typically, the method employs the system of the invention. Optionally, the method further comprises the step of providing an interlayer of porous material between said arrangement and said structure, such that said channels indirectly abut said structure via said porous material. The porous material typically comprises any one of or combination of woven fabrics or non-woven mats, optionally made from fibreglass, polyester, polyamide, polypropylene, jute, cotton, or any other suitable material.

Optionally, the structure may be heated at least during application of said suction.

In one embodiment, the method is particularly adapted for drying a structure comprising a screed, wooden floors laid on concrete or wood, or the like, wherein said arrangement is sealingly abutted over said structure and said suction is applied to said channels, and exhausting air, water and water vapor to a location away from said structure.

In another embodiment, the method is particularly adapted for drying a structure comprising a tiled floor, in particular a porous bed on which said floor is laid, further comprising providing a first plurality of vent holes between said porous layer and an external surface of said tiled floor, and subsequently sealingly abutting said network over said structure such that said holes are overlaid by said channels, applying said suction to said channels, and exhausting air, water and water vapor to a location away from said structure. Preferably, the holes are located at intersections between adjacent tiles. Optionally, a second plurality of vent holes is provided outside of said channel arrangement and provides communication between said porous layer and an external surface of said tiled floor, said second plurality of vent holes allowing ambient air to circulate from outside of said arrangement to said porous layer prior to being extracted by said suction via said first plurality of vent holes. Optionally, the method further comprises the step of providing forced circulation of dry or heated air drawn by suction into said porous layer via said second plurality of vent holes. Dry or heated air may be provided by dehumidifying or heating the air in the space above the floor tiles, or by using a second arrangement comprising a network of channels, similar to the network of channels used for extracting air, water, water vapor and so on from the structure, in communication with a suitable source of dry or heated air, wherein the channels of said second arrangement are overlain over said second plurality of vent holes.

In another embodiment, the method is particularly adapted for drying a structure comprising a wooden floor laid on a tiled floor, in particular a porous bed on which said tiled floor is laid, further comprising removing one or more strips of wood to expose portions of said tiled floor, providing a first plurality of vent holes between said porous layer and an external surface of said tiled floor, and subsequently sealingly abutting said network over said structure such that said holes are overlaid by said channels, applying said suction to said channels, and exhausting air, water and water vapor to a location away from said structure.

Optionally, a second plurality of vent holes are provided outside of said arrangement and provides communication between said porous layer and an external surface of said tiled floor, said second plurality of vent holes allowing ambient air to circulate from outside of said arrangement to said porous layer prior to being extracted by said suction via said first plurality of vent holes.

Advantageously, the channels are arranged on lines over said exposed portions of said tiles. Optionally, the method further comprises the step of providing forced circulation of dry or heated air drawn to said porous layer by suction via said second plurality of vent holes. In other words, the method may further comprise the step of drying or heating the air in a space above the tiles and feeding dried or heated air to said porous layer via said second plurality of vent holes.

Optionally, the dry or heated air may be directed to said second plurality of vent holes by means of a second arrangement comprising a network of channels, similar to the network of channels used for extracting air, humidity and so on from the structure, in communication with a suitable source of dry or heated air, wherein the channels of said second arrangement are overlain over said second plurality of vent holes.

In all embodiments, the channels can be overlaid to directly cover a first portion of said structure, leaving a second portion of said structure uncovered by said channels. The area ratio between said first area and said second area is typically determined by the drying technician. The greater this ratio, the faster the drying process.

Thus, according to the invention, the channeling members provide fluid communication between a plurality of zones and the suction ports to enable sufficient flow of air, water and vapors between the area of the structure on which the system is overlaid and the ports, to overcome the inevitable ingress of ambient air, and maintain reduced pressure and forced circulation of unsaturated air through the structure to be dried. In the absence of said members, in the first embodiment of the system, the membrane would be sucked onto the surface reducing the flow of air and vapors therethrough, even if a porous interlayer is placed between the membrane and the structure, and thus the influence of the suction field is very much reduced, in fact to the point of ineffectiveness.

A substantial ingress of ambient air into a structure covered only by a waterproofing layer or by an impermeable membrane cannot be avoided due to the porosity of the structure and voids inherent in laid cementitious structures, as well as to lack of air-tight sealing of the waterproofing layer and between the, for example, screed and the surrounding walls and due to the passage of tubes and cables through the screed. If a network of channels of sufficient cross-section connected to a powerful suction as in the present invention is not applied, the inevitable ingress of ambient air strongly reduces the effect of low pressure and extraction that should be produced for effective drying and nullifies it at a short distance from the suction tube, regardless of whether the suction tube is inserted into the screed or connected to a membrane placed over the structure. Even if a porous mesh is placed underneath the membrane it is still ineffective, because the very small flow rate that is possible through the mesh is effective only to a very short radius around the suction port, typically about 30 cm, and beyond this distance it cannot match the much greater rate of ingress of ambient air and in this arrangement also the effect of low pressure and extraction is nullified.

On the other hand, in the present invention, channels of sufficiently large cross-section area are laid sufficiently close to one another to overcome the ingress of ambient air by extracting it as well as water, air and vapor from the screed, for example, and conducting them to the suction apparatus, thereby maintaining sufficiently low pressure over the whole area to enhance evaporation and drying. The rigid or semi-rigid nature of the channels prevents them from collapsing under the reduced pressure therein during operation of the drying system. This network of channels is connected through one or more ports to one or more tubes of sufficient cross-section that lead to one or more suction apparatus of sufficient capacity. Furthermore, the forced circulation of the ingressed unsaturated ambient air through the, for example screed, to be dried continuously replaces the saturated air in the pores and voids and over the surface of the screed and further enhances the drying process through increasing the rate of evaporation from the wet screed.

The present invention thus makes use of the enhanced water extraction potential under reduced pressure combined with intensive circulation of reduced pressure unsaturated or dried air through the wet construction material and which can be applied using portable equipment and materials in the field to dry wet parts of building structures, especially floor structures. For example, wet screed and concrete, wet wooden floors, wet porous layers (especially sand) underneath tile floors as well as underneath tile floors on which wooden floors are laid.

Thus, according generally to the present invention, there is provided a method of drying building structures which comprises applying a temporary network of inverted channels of significant cross-section over the area of the structure to be dried, sealing it against the structure to minimize the ingress of ambient air that does not circulate through the wet structure, and applying a strong suction through the network of inverted channels, thereby reducing the pressure over the structure and extracting air, water and vapor from the structure.

The efficiency of the method is enhanced if a flexible impermeable membrane is laid on top of the network of inverted channels and sealed to the surface of the structure, covering the areas between the individual inverted channels and saving the need to seal the individual inverted channels to one another and to the structure. The drying effectiveness is also enhanced by applying suction to the areas between the individual channel members, thereby improving the extraction of water, vapour and air from these areas.

One or more suction sources are connected to the network of inverted channels through one or more inlet suction ports. In the case wherein the membrane is used, holes are provided in the membrane for the passage therethrough of the suction ports, and the membrane is sealed with respect to the suction ports. Suction is applied reducing the air pressure in the network of inverted channels as well as over the area that is under the membrane between the individual inverted channels. Suction is applied to extract water, air and water vapor from the network of inverted channels as well as through the channels from the areas under the channels and under the optional membrane between the individual inverted channels. The water, air and water vapor are extracted from the pores and voids in the structure. Furthermore, due to the porosity and voids in the structure, the powerful suction induces substantial ingress of unsaturated ambient or dried air pulled to the reduced pressure area under the inverted channels and under the membrane. The intensive flow of unsaturated ambient or dried air through the wet structure accelerates the evaporation and enhances the drying of the structure. The reduced pressure and strong extraction are maintained until the desired degree of drying has been achieved.

The present invention ensures fast and effective drying processes without damage to the structures, regardless of the degree of porosity of the wet structures.

The present invention ensures that in case of low porosity, the lowest viable (economically and technically) pressure is maintained over the area, enhancing low-pressure evaporation assisted with the evaporation induced by the relatively little flow of unsaturated ingressed air through the structure.

The present invention ensures also that in case of high porosity, a strong flow of ingressed unsaturated ambient air through the structure enhances the rate of evaporation and compensates or surpasses for possible reduction in the rate of evaporation induced by diminished evaporating effect of low pressure.

Furthermore, the present invention ensures that the lowest viable pressure (economically and technically) as well as the strongest viable circulation and extraction of unsaturated ambient air ingressed through the porous structure are maintained throughout the whole area to be dried and not just in a small area around the suction port.

The degree to which the pressure is reduced will generally be a compromise between reducing it as much as possible (as the greater the reduction the quicker the drying) and the practicality and cost of doing so, taking into account the inevitable ingress of ambient air through the pores and voids of the structure.

As described herein, and in order to increase the rate of drying, the ingressed air may be dried with a suitable apparatus to a lower relative humidity than that of ambient air. This can be done either by dehumidifying the whole space of the room from which air ingress occurs or by feeding dry air from a drying apparatus to the areas from which air ingress takes place using suitable apparatus for confining the dry air to these areas. The confining can be done by laying another impervious membrane over the air ingress areas or by laying another system of inverted channels over the air ingress areas, or by combining both through laying the other impervious membrane over the other system of inverted channels laid over the air ingress areas. Preferably in order to assist the transportation of water, air and water vapor from the areas between the inverted channels, a porous interlayer can be laid between the network of inverted channels and the material being dried, for example a cloth or mat or other suitable porous material which can be easily applied and as easily removed. In addition, a porous interlayer can be laid between the impervious membrane and the network of inverted channels to serve as a cushion against puncturing or rupturing the membrane.

The method of the invention, when used for drying wooden floors has major advantages over alternative methods for drying wooden floors: A. The wooden floor is dried faster, before the water damage gets worse.

B. Under suction a steady and even pressure is applied all over the surface of the wooden floor, thereby flattening the wooden floor and restoring it to its initial flat condition.

C. The wooden floor and the under-floor are dried simultaneously, thereby preventing future damage to the wooden floor by the migration of wetness from the under-floor to the wood planks or blocks that make up the floor.

D. Unlike other methods, drying is even and thorough.

It is usually preferred to increase the rate of drying by applying heat to the material being dried at the same time as applying suction. Heat may be applied by the heating system of the building, by portable microwave devices or by generators of hot air or any other effective means. The method of the present invention may be applied mainly in drying floor structures in buildings, but may be applied also in a variety of different circumstances for different purposes at different stages and, by way of illustration a number of these are discussed in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non- limiting example only, with reference to the accompanying drawings, in which: Fig. 1 schematically illustrates in plan view a general layout of the first embodiment of the system of the invention.

Figs 2A to 2J illustrate in isometric view various forms of the channels used in the embodiment of Fig. 1.

Figs 3A and 3B illustrate, in plan view and sectional view along X-X, respectively, the embodiment of Fig. 1 used for drying a screed.

Figs 4A and 4B illustrate, sectional side view, the embodiment of Fig. 1 used for drying a wooden floor laid on a concrete slab or on a wooden support, respectively.

Figs 5A and 5B illustrate, in plan view and side sectional view, respectively, the embodiment of Fig. 1 used for drying a porous layer underlying a tiled floor.

Figs 6A and 6B illustrate, in plan view and side sectional view, respectively, the embodiment of Figs. 5A and 5B, further incorporating means for forcing heated an/or dry air into the porous layer underlying a tiled floor.

Fig. 7 illustrates in side sectional view, respectively, the embodiment of Fig. 1 and the embodiment of Fig. 11 used for drying a porous layer underlying a tiled floor on which is laid a wood floor.

Fig. 8 illustrates a variation of the embodiment of Fig. 1.

Figs. 9A and 9B illustrate another variation of the embodiment of Fig. 1, extended and collapsed, respectively.

Fig. 10 illustrates another variation of the embodiment of Fig. 1.

Fig. 11 schematically illustrates in side sectional view a general layout of the second embodiment of the system of the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring to Fig. 1,2A-2J, 3A-3B a first embodiment of the system of the invention, generally designated with the numeral 10, comprises elements and features as described herein, in particular a channeling arrangement having at least one cavity forming spacing member in the form of a network 20 of channeling members 50 connected to a suction or vacuum source 80 via one or more lines or conduits 70. The network 20 is typically made from a number of elements that are portable, and is temporary being removed from the structure after the drying process. The channeling members 50 are designed for easy and quick assembly and disassembly with respect to forming and dismantling network 20.

Herein, the terms"suction source"and"vacuum source"are used interchangeably, and thus the vacuum source 80 may comprise, for example, a suitable suction or vacuum pump, or a vacuum line connected to a suitable ejector arrangement, for example.

The channeling members 50 are each typically in the form of an inverted gutter configuration of the like, comprising a duct having a open bottom end 52 and having a suitable, preferably impermeable duct wall 54 forming a channeling passage or volume 58 enclosed between said bottom end 52 and the wall 54. The members 50 are also typically modular, having at least one side opening 55, also referred to herein as end openings, that is connectable to a corresponding side opening of another member 50, for example by means of simply overlapping juxtaposed ends of adjacent members 50 at said side openings, allowing fluid communication between adjacent members 50 thus joined, as illustrated in Fig.

2I. Optionally, and as illustrated in Fig. 2G, an overlapping flange arrangement 51 may be provided to join adjacent members at the side openings. Alternatively, adjacent members 50 can be assembled to one another with butt joints at the facing side openings thereof, as illustrated in Fig. 2J.

The members 50 may have any suitable transverse cross-sectional shape, typically semi-circular, but may include any other arcuate form, or any convex form including rectangular, semi-hexagonal, polygonal, and so on. The transverse cross-section typically comprises, but is not restricted to, an area of between about 9 cm2 and about 40 cm2. Thus, the transverse cross-section area may be less than 9 cm2 or greater than 40 cm2. In each case, the wall 54 may comprise any form of sides and top, and any cross-section, such as to provide a reasonable spacing between the open bottom end 52 and the duct wall 54 through which air, water and water vapor can flow throughout the network and out to the suction source 80, as will be explained in greater detail hereinbelow. One or more members 50 of the network 20 comprise an inlet or suction port 57 that is adapted for sealing connection to a said conduit 70. The ports 57 allow one or more (as many as necessary) suction apparatus to apply reduced pressure or suction to the building structure under the network of channels 50 for drying as well as to extract the ambient air ingressed through the pores and voids in the building structure. This is illustrated in Figure 3B, which shows a vertical section through a screed laid on a concrete slab.

The open bottom end 52 is adapted for laying over a surface that is to be dried using the system 10, and thus comprises a plurality of edges 56 that abut the surface.

In this embodiment the connection between said members 50 via side openings 55, as well as the interface between the bottom ends 52 and the surface do not require to be locally sealed at all with respect to one another. Rather, a substantially impermeable sealing membrane 40 is provided that is overlaid to cover the full extent of the network 20, and this membrane is sealed on its perimeter to the surface of the structure to be dried, as will be described further hereinbelow. The sealing membrane 40, while being essential to this embodiment, is not required at all in other embodiments of the invention, such as for example the second embodiment described hereinbelow. Accordingly, the membrane may be regarded as an optional feature of the invention.

The members 50 are typically made from a rigid or semi-rigid convenient material, for example of plastic, metal, wood or composites, such as glass fibre for example, in order to maintain the cross-sectional shape during operation of the system 10, when ambient pressure on the outside of the members 50 is greater than on the inside thereof.

Referring particularly to Figs 2A to 2J the members 50 may comprise any suitable shape. For example, the basic building unit for the members 50 is in the form of an elongate semi-cylindrical duct 67, having open ends at each longitudinal end thereof (Fig. 2A). The elongate members 67 may be of any longitudinal length, and optionally may be cut to any desired length. Other members 50 may be in the form of L-shaped, V-shaped or U-shaped elbow members 60, having two side openings for connecting to two other members 50, such as two elongate members 67, for example, at any suitable angle and/or lateral spacing between one and the other said members 67 (Fig. 2C). Other members 50 may be in the form of cross-members 63 having four, orthogonally disposed side openings, each of which is connectable to another said member 50 (Fig. 2D). Other members 50 may be in the form of a T, such as T-shaped members 64, enabling three other members 50 to be connected thereto (Fig. 2B).

Other members 50 may include end members 65, which have only one side opening for connection to another member 50 (Fig. 2F). Other members 50 can be in any form as described above and further comprise a said inlet port 57, for example member 68 (Fig. 2E).

Optionally, the network 20 comprises plug members 69 for plugging any side openings 55 that remain open and unconnected to another member 50.

The members 50 are connected in any desired combination or permutation such as to cover the surface 90 to be dried in the most optimal manner possible, typically in the form of one or more manifolds having outlet members 50 that extend to wherever desired.

Thus, the network of members 50, which have the appearance of inverted channels, may be easily constructed from sections which can simply be assembled, for example by simply overlapping the ends thereof comprising the side openings, or by abutting said ends, as they do not need to be sealed to one another. The membrane 40 serves to seal off the entire area it covers. Thus, even perforated or mesh-wall plastics or metal inverted channels or tubes and joint pieces into which the tubes are push fitted may also be used to construct the network 20.

For maximum effect, the full surface 90 is covered with said members 50.

However, very efficient drying may also be obtained for a surface that is only partially covered with said members 50. For example, and referring to Fig. 3A, the members may be interconnected to form a substantially rectangular grid, in which part A of the surface is covered by the members 50, and parts B of the surface 90 are not covered by said members 50. Nevertheless, adjacent rows 21, 22, 23, 24 and columns 25,27 of said members 50 are sufficiently close such that the suction field applied by the members 50 on either side or at the periphery P of such uncovered areas B extend to substantially the full extent thereof, and can therefore be dried by virtue of the surrounding members 50, as will become clearer herein. Thus, the members 50 are sealed with respect to one another as well as at the open bottom end 55 of the members 50 to the structure.

The sealing membrane 40 is used in this embodiment to seal the area 90 to be dried. The membrane 40 may comprise any suitable plastic film or a rubber sheet with low permeability to air and to water vapor. The term impermeable as used herein is not intended to exclude materials which have a low but still measurable permeability to air, for example plastics sheets, but the permeability of the membrane must be sufficiently low to allow a reasonable degree of reduced pressure to be maintained to achieve the desired drying. Many types of sheet plastic or rubber materials, such as polyethylene, polyamide (Nylon), polyester (Mylar) are suitable. If the area 90 is large, it may be covered with two or more sheets sealed together where they overlap. The membrane 40 may be of any thickness, typically 0.1 to 2 mm, though it may be thinner or thicker as desired, and typically reusable, enabling the same membrane 40 to be reused a number of times until it becomes unusable, for example due damage thereto.

Alternatively, the membrane 40 may comprise suitable plastics films which are readily and cheaply available, easily handled and tailored to the shape of the area to be dried and disposable after use.

In particular, the membrane 40 must be sufficiently large such as to extend past the outside periphery Q of the network 20, so that the free edges of the membrane 40 form a peripheral zone 44 around the network 20 in direct contact with the surface 90. The zone 44 is sealed with respect to the surface 90 for the purpose of minimizing unwanted ingress of ambient air between the surface 90 and the membrane 40, without passing through the structure to be dried. Sealing may be performed by any effective means such as sealing tapes, adhesive tapes, flexible seals, setting suitable weights along the perimeter zone 44 of the membrane 40, adhesive or solvent bonding or mechanical clamping, among others.

The said inlet ports 57 protrude through suitable apertures 48 in the membrane 40, and are thus sealed with respect thereto to prevent unwanted ambient air ingress into the volume enclosed by the membrane 40. Sealing of the ports 57 with respect to the membrane 40 may be carried out in any suitable manner, for example by means of sealing tapes, adhesive tapes, flexible seals, adhesive or solvent bonding or mechanical clamping, among others.

Optionally, the membrane may be bonded or otherwise attached or joined to the members 50.

Preferably, and as illustrated in Fig. 3B, an intermediate layer 49 is provided between the membrane 40 and the members 50 as well as over the exposed portions B of the surface 90. This intermediate layer 49 is typically made from a suitable porous material, and may comprise, for example woven fabrics or non-woven mats for example made of fibreglass, polyester, polyamide, polypropylene, jute, cotton, or any other suitable material. The intermediate layer 49 provides several advantages. For example, it protects the membrane 40 from being torn by raged edges or the like that may exists on the members 50 or on the exposed areas B, and furthermore facilitates some suction of air and vapor from the exposed areas B to the members 50, to assist drying thereof.

The system 10 according to the first embodiment may be used in a number of different ways, according to the type of floor or surface that it is desired to dry, for example:- (a) screeds; (b) hardwood (parquet) floors and concrete or wood sub-floors; (c) sand or other porous materials under floors (especially tile floors) without damaging the floors; (d) sand or other porous materials under tile floors on which wooden floors are installed with minimum damage to the wooden floor.

The method of the invention, as applied to each of the drying examples above shall now be described in detail.

Referring to Figs. 3A and 3B, a screed 92 overlies a bed or slab of concrete 94, and the first step of the method is to cover the area of the screed with a network 20. The area 90 of the screed 92 to be dried is overlaid with network 20, such that the members 50 directly overlie a first portion A of this area, and so that a second portion B is exposed. The area ratio between the covered portions A and the uncovered portions B may be varied to suit the particular conditions of the surface 90 to be dried, and the capacity of the system 10, in particular the suction pump 80. Typically, the larger the ratio A: B is, the more effective and fast the drying process becomes, and in some cases area B may be substantially zero. In practice, there are usually some open spaces, and this ratio is typically determined by the drying technician operating said system.

Further, preferably, the first portion A and second portion B are distributed as uniformly as possible over the structure to be dried. The exact shape into which the network 20 is formed will generally depend on the shape and size of the area to be dried, and the particular conditions, for example the presence of obstacles such as piping, protrusions, voids or fixed furniture. The modular nature of the members 50 allows great versatility in covering areas of varying shape and size.

The size of the area to be covered and treated at any one time typically depends upon the capacity of the suction source 80 available, and on the characteristics of the area to be dried. When the network 20 is in place, the intermediate layer 49 and then the membrane 40 are draped over the network 20. The membrane 40 is then sealed at 41 with respect to the inlet ports 57 and at 44 with respect to the surface 90, as described above. Then conduits 70 are sealingly connected to the suction source 80 and to the ports 57, and suction is induced at the bottom ends 55 of the members 50.

Preferably, in the above embodiment wherein a membrane 40 is used for sealing the network 20, prior to overlaying the network 20, an interlayer 96 of porous material is laid over the screed 94, to improve the flow of air, water and water vapor from zones of portion B to the members 50. The porous layer 96 may comprise woven fabrics or non-woven mats for example made of fibreglass, polyester, polyamide, polypropylene, jute, cotton, or any other suitable material.

Optionally, the screed can be heated with any effective means during the application of suction, for the purpose of accelerating the drying process.

Generally, a very convenient means for providing the required heating capacity is the heating system of the building. Other alternatives for heating include various types of hot air generators, special microwave heaters or infra-red heaters. The efficiency of heating with warm air can be enhanced by confining the warm air flow with a temporary enclosure positioned as necessary for the required heating.

During operation of the system 10 for drying screeds, when suction or reduced pressure is first applied, air, water and vapor are sucked away from the surface of the screed as well as from inside the screed through the pores and voids in the screed to the network 20 of channel members 50 to be expelled to the ambient atmosphere at a location suitably distanced from the screed by the suction means 80. The driving force is the reduced pressure applied over the area being dried combined with the optional circulation of unsaturated or dry air through the screed. Then, the effects described above of accelerated evaporating under reduced pressure as well as by circulating unsaturated or dry ingressed air through the screed come into effect. The rate of water and water vapor extraction from inside the screed may also be accelerated by slightly roughening its surface, e. g. by gentle sanding for exposing more pores.

The approach described above for drying screeds may be applied to other parts of building construction, e. g. concrete, sprayed-on fireproofing materials or insulating materials, mutatis mutandis.

The method of the invention when used for drying hardwood (parquet) floors and concrete or wood sub-floors usually works faster than other alternative methods known in the art. As with the method for drying screeds, the wooden floor area 190 to be dried is covered with a network of members 50 for example, as shown in Figs. 4A and 4B. The network 20 can be laid directly on the wooden floor 190 and under a membrane 40, but preferably it is laid on a porous layer 96 put on the wooden floor 190 with a porous intermediate layer 49 between it and the membrane 40, similar to the manner described above for the screed, mutatis mutandis.

Referring to Fig. 4A, in the case where the wood floor 190 is laid on a concrete 94 and screed 92 sub-floors (or on a concrete 94 sub-floor), suction can reduce the pressure to a considerably low pressure. The wooden floor 190 dries simultaneously with the concrete 94 and screed 92 sub-floor. As illustrated in Fig. 4A, if the wooden floor area does not reach a wall, the membrane 40 preferably overhangs the full wooden floor area, and is sealed at 44 with respect to the concrete sub-floor. In cases where it is impossible or impractical to seal the membrane against the screed 92 or the concrete slab 94, it is sealed against the side wall or against the periphery of the wooden floor. The mechanism of drying is similar to that of drying screed: enhanced evaporation by the simultaneous actions of low pressure and circulation of unsaturated or dried ingressed air through the wet structures.

Referring to Fig. 4B, the wood floor 190 is laid on wood sub-floors 195, and in this and some other cases, not illustrated, a low pressure is difficult to achieve because of the presence of spaces 196 in the wooden structure that prevent proper sealing. In these cases, the flow of unsaturated and preferably dry ingressed air through the material to be dried is generated using a powerful suction source as the driving force for the high flow of unsaturated or dried air through the wet structures. This method may be used to effect fast and simultaneous drying of the wooden floors and sub-floors. Drying the wooden floors and sub-floors effectively usually restores the wooden floors to their proper condition if it is done without delay after the occurrence of water damage.

The sooner the drying is exercised the better the probability for successfully restoring the damage.

In the cases where a wood floor is being dried according to the invention, it should be noted that when an embodiment of the invention employing said membrane 40 is used, application of suction to the system 10 results in the creation of a downwards force onto the membrane, which gets transmitted to the floor, due to the pressure differential between atmospheric ambient outside the membrane 40 and the inside surface of the membrane 40. This evenly distributed downward force helps to flatten the wood planks that tend to swell and stick out upwards as they become wet.

The method of the present invention can also be used for drying sand or other porous materials under floors, in particular tiled floors, without generally causing damage to the floor tiles. As with the other examples described above drying of such under-floor structures is based on applying a powerful suction to the porous material through a network 20 of channeling members 50, and the drying mechanism is based on enhanced evaporation by the simultaneous actions of low pressure and intensive circulation of unsaturated or dried ingressed air through the wet porous material.

The drying method is executed as follows. Referring to Figs 5A and 5B, a tiled floor 290 comprises a plurality of tiles 292 usually in rectangular formation, set on mortar 294 which is laid on a porous sand layer 296 over a concrete slab 298. A plurality of small holes 295, typically along parallel rows, are drilled at the interfaces 299 between adjacent tiles, preferably at the corners 297 between four mutually adjacent tiles 292 to a depth penetrating the mortar 294 until the sand layer 296 is reached. If necessary, additional holes may be drilled along the space 299 between each pair of adjacent tiles. Typically, such tiles are laid with small spaces between tiles being filed with cement, grout or other filler material.

The holes 295 penetrate to the underfloor layer of sand 296 or other porous material that is to be dried, and allows water, air and water vapor to be extracted therethrough. At the same time, the holes 295 are small enough to avoid damage to the tiles 292 and to be easily repaired after drying. If the spaces 299 between the tiles 292 are too small or not sufficiently sealed, the holes 295 can be drilled in the tiles themselves, preferably at locations in which the holes can be repaired without significant visual effect in the tiles. The holes 295 serve as conduits to enable a strong suction force to be applied underneath the tiles, thereby reducing the pressure on the sand 296 or other porous substance that may be thereat, as well as extracting water, air and water vapor from the sand underneath the tiled floor and generating a strong flow of unsaturated or dry ingressed air through the wet sand. Ingress of air is indicated at BB in Fig. 5.

In the next step, a network 20 of channeling members 50 is overlaid over the rows of drilled holes, and a sealing membrane 40 can be laid over the members 50 and sealed to the floor thereby sealing the whole area at 44 in a similar manner to that described above for the screed, mutatis mutandis.

Preferably, though, the network 20 is laid over a previously applied porous layer 96, and a porous inter-layer 49 is applied between the members 50 and the membrane 40. In this case the porous layer serves also to limit the suction of sand through the holes 295 to negligible levels.

In the next step, a powerful suction force is applied to the network 20 through one or more inlet ports 57, acting on the wet sand 296 through the drilled holes 295 in the tiled floor. Effective drying is achieved by accelerating the evaporation of water from the sand and continuously and forcefully extracting large volumes of air and water vapor from the sand through the holes and the inverted channels network, and replacing them with unsaturated or dried ingressed air. The high rate of evaporation and of drying the sand is due to reducing the pressure over the sand as well as generating a strong flow of unsaturated or dry ingressed air through the wet porous sand.

As before, the drying process can be further accelerated by drying the air in the room with one or more dehumidifiers or alternatively by feeding hot air to the room, thereby circulating underneath the floor ingressed air that is dryer than ambient air. Optionally, and referring to Figs. 6A and 6B, the dry air can be introduced under the tile floor 290 to the sand 296 through holes 285 drilled outside the sealing membrane 44 especially for this purpose, as indicated at AA in Fig. 6B. This dry air is drawn under the floor 290 and sucked out from under the floor via holes 295 after collecting water vapor by the pull of the powerful suction through the members 50. Alternatively, and as further illustrated in Figs.

6A and 6B, dry air, for example, from one or more dehumidifiers or heaters, can be fed to a second network 20'of members 50 or to another temporary confinement to be sucked under the tile floor, on which the second network 20'is positioned, through the special holes 285 drilled for this purpose outside the membrane 40. The second network 20'of members 50 feeding dry air may preferably encircle the system 10, or be laid in parallel to as many of its component parts as possible,, and in any case can be sealed to the floor directly, or with a second sealing membrane laid on top of the channels and sealed to the floor, similar to the first network 20, mutatis mutandis. Alternatively the dry air channels may not be sealed but held in place with weights or with other fixing means. In this case, sealing is not so crucial, since the escape of excessive dry air to the space of the room has no adverse effects on the drying process.

Referring to Fig. 7, the method of the present invention can also be used for drying sand 296 or other porous materials under tile floors 290 on which a wooden floor 390 is installed, with minimal damage to the wooden floor 390.

This method is similar to the method described above for drying sand or other porous materials under tile floors, mutatis mutandis, with the main difference that a special layout of the network 20 is required, aimed at minimizing the damage to the wooden floor 390.

In this case, the first step comprises the minimal removal of wood planks or parts of planks from the wooden floor 390 to expose at 395 the tile floor 290 under these planks. The size, shape and position of areas 395, as well as the distance between adjacent exposed areas 395 is determined by the drying technician, based on the local conditions and on the available equipment. The holes 295 in the tile floor 290 are drilled in the exposed strips of tiles. Instead of laying a two-dimensional network 20 of members 50, as is typical in the other applications of the method described above, members 50 are usually arranged in straight lines and laid on each exposed areas 395 (or part of such an area) of tiles, wherein each such line of members 50 is separately connected to a different or to a common suction source (not shown in this figure). The line of members 50 may be continuous or intermittent with joining conduits. The shape and size of members 50 may be adapted for allowing minimal removal of wood planks or parts of planks. All other details of the drying work are the same as with the method described above for drying a porous layer underneath a tile floor, including sealing of the channel members 50 to the tile floor 290, typically with a sealing membrane 40 and intermediate layer 49, as described above mutatis mutandis.

The channel members 50 may also be directly sealed to the tile floor 290 with sealing tapes, adhesive tapes, flexible seals, adhesive, weights, or any other suitable means, when the system according to the second embodiment, described below, is used.

After the completion of the drying operation, all of the drying materials are removed and new wood planks or parts of planks are installed on the exposed areas 395 of tiles.

Referring to Figs. 9A, 9B, in a variation of the first embodiment of the system 10 described above, the members 50'comprise a skin 54'made from a relatively non-rigid material, such as for example, sheet plastic or rubber materials, including but not limited to polyethylene, polyamide (Nylon), polyester (Mylar), reinforced with shape retaining ribs 55'made from a rigid or semi rigid material, such as for example, metal, plastic, wood, or a composite material. While the members 50'according to this embodiment may adopt any of the shapes described above for the first embodiment, mutatis mutandis, such members 50'are preferably elongate members, and when not in use can be stored in a compact configuration, as illustrated in Fig. 9B, by collapsing the member in a longitudinal direction such as to bring together adjacent ribs.

This configuration for the channeling members 50'provide a great deal of flexibility in the manner in which a surface may be covered for the purpose of drying thereof. The members 50'are very flexible, and may be curved into arcs or spirals, for example, and joined with rigid or semi-rigid members 50, as illustrated for the first embodiment above.

Alternatively, the ribs 55'may be made from non-rigid material, in the form of tubes that are inflatable with air or other gas, or water or another liquid, to provide the stiffness required. Such ribs 55'may be inflated individually, or may be interconnected so that all the ribs may be inflated simultaneously.

Optionally, and as illustrated in Fig. 8, adjacent ribs 55'may be alternately joined one to the other in a zig-zag manner via webs 56', affording some longitudinal rigidity as well.

Optionally, the members 50'comprise a skirt 57'at the bottom ends thereof, adapted for sealing against the surface that is to be dried, to facilitate sealing between the members 50'and the surface, in the event that a said membrane is not used (see the second embodiment below). Sealing of the bottom end of the members 50'with the surface may be performed by any effective means such as sealing tapes, adhesive tapes, flexible seals, setting suitable weights along the skirt 57', adhesive or solvent bonding or mechanical clamping, among others.

In another variation of the first embodiment, not illustrated, the cavity forming spacing element is formed integrally with membrane 40, which comprises integral channels formed therein by means of supporting ribs similar to said supporting ribs 55'described above, mutatis mutandis, bonded or otherwise joined to a lower face of the membrane 40.

In yet another variation of the first embodiment, and referring to Fig 10, the at least one cavity forming spacing member is in the form of a channeling arrangement 20"comprising an upper panel 24", on the underside of which are joined a plurality of vertical webs or ribs 22", wherein channels 50"are defined between each adjacent pair of ribs 22"and a portion of the panel 24" therebetween. The channels 50"can be arranged in any suitable pattern with respect to the panel 24", for example radially as illustrated in the figure.

Optionally, and preferably, side walls (not shown) are provided to enclose the sides of the arrangement 20", allowing sealing to the floor surface directly.

Otherwise, a membrane is draped over the whole arrangement 20"and sealed to the floor at the periphery of the membrane. One or more inlet ports 27"may be provided on the panel 24", providing fluid communication between the channels 50"and a vacuum or suction source (not shown). In operation, one or more of said arrangements 20"is overlaid over the floor or other structure to be dried, such that the lower edges 28"of the webs are in contact with the surface. An impermeable membrane (not shown) can then be draped over the arrangement 20"and sealed with respect to the port 27"and the surface, in a similar manner to that described above, mutatis mutandis.

In yet another variation of the first embodiment (not illustrated) the at least one cavity forming spacing element is in the form of an open box having an upper inlet port communicating with a plenum chamber formed therein when the open bottom is overlaid over the structure to be dried and sealed to it on its periphery. As with other embodiments described herein, one or more such elements may be overlaid over the structure to be dried as required. An impermeable membrane may be overlaid over the box-like structure and sealed with respect thereto, and the port is connected to a suction source.

The variations of the first embodiment described above may be used in a similar manner as described above for the first embodiment mutatis mutandis.

A second embodiment of the system of the invention, illustrated in Fig.

11, comprises all the elements and features as described for the first embodiment and variations thereof above, with the following main differences, mutatis mutandis. In the second embodiment, there is no sealing membrane overlaid over the surface to be dried. Thus, the system 100 comprises at least one cavity- forming spacing element in the form of a network 120 of channeling members 150, similar to the network 20 and members 50, mutatis mutandis, operatively connected to a vacuum or suction source 80 via conduits 70. In this embodiment, rather than using a membrane, the channeling members 150 are directly connected one to the other in a substantially salable manner, for example by means of sealing tapes, adhesive tapes, flexible seals, adhesive or solvent bonding or mechanical clamping, among others. Similarly, the bottom ends 152 of the members 150 are adapted for sealing against the surface 90 (of a screed 92 overlaid on concrete 94, for example), and may comprise a skirt (not shown) to assist the same. Sealing of the bottom end 152 with the surface may be performed by any effective means such as sealing tapes, adhesive tapes, flexible seals, setting suitable weights on the members 150, adhesive or solvent bonding or mechanical clamping, among others. Further, the inlet ports 157 are joined to the members 150 in a similar manner to the inlet ports 57 described above.

The second embodiment and variations thereto described above may be used in a similar manner as described above for the first embodiment mutatis mutandis, with the following major difference. In the step of overlaying the network over the surface to be dried (including the surface under which there is a layer of porous material to be dried) the various members 150 are sealingly joined one to another to form said network, and the members 150 are sealingly abutted over the surface directly, rather than by means of an optional membrane.

For example, referring to Fig. 7, in the method described above for drying wooden floors overlaid on a tiled floor, the members 150 can be sealed directly to the tiled floor 290. Similarly, the second embodiment can be used for drying screed, or for drying a porous layer underneath a tiled floor, without using the optional membrane.

In the method claims that follow, alphanumeric characters and Roman numerals used to designate claim steps are provided for convenience only and do not imply any particular order of performing the steps.

Finally, it should be noted that the word"comprising"as used throughout the appended claims is to be interpreted to mean"including but not limited to".

While there has been shown and disclosed exemplary embodiments in accordance with the invention, it will be appreciated that many changes may be made therein without departing from the spirit of the invention.