The present invention relates to a method of treating a roof, in particular to but not limited to a method of treating a roof comprising a fault defining a leak.

Roofs may be in the form of a pitched roof, a flat roof and in certain cases may comprise both pitched and flat areas. Under the Building Regulations outlining the method and minimum standard to be met in construction in the UK, a 'flat roof is defined as one having a pitch of 10 degrees or less.

Flat roofs have been used for hundreds of years and are preferred for their versatility in design because they can be used, for example, as terraces, balconies or gardens.

A typical flat roof may be said to comprise three major elements: a structure; a deck; and one or more waterproof layers or membranes. A layer of insulation may be provided as part of the roof construction.

The structure provides the strength and shape of the roof and is designed to support and maintain the integrity of the loads the roof has to support. The structure, depending upon the building type and the spans involved, may comprise timber, steel or concrete.

The deck is a substantially flat surface which may be supported by the structure or integrally formed with the structure. The deck supports and receives the waterproof layer(s). A separating layer and a support layer may be positioned between the waterproof layer(s) and the deck. The waterproof layer(s) may comprise a bituminous or roofing felt based membrane, mastic asphalt, lead, stainless steel, copper, zinc or composite metal alloys. Where the waterproof layer(s) is metallic, a separating layer is usually employed between the waterproof layer(s) and the deck.

The waterproof layer(s) may define a top layer of the roof which is designed to protect the construction against the elements or a separate top layer may be employed in the construction. Where the waterproof layer(s) define the top layer of the roof, the waterproof layer may be constructed to accept foot traffic and/or shielded against the effect of sunlight by means of a reflective coating or chippings.

The insulation is positioned underneath the waterproof layer(s) and depending on the location of the insulation relative to the deck, the roof is classified as a cold-deck roof (insulation located beneath the deck) or a warm-deck roof (insulation located above the deck).

Roof life depends on the material used to construct the top layer of the roof and is generally about 20 years for a felt top layer, 25 years for a bitumen top layer and up to 50 years for a top layer formed of lead, copper or steel as these materials weather and form oxide coatings which help in their longevity.

The main cause of failure in domestic flat roofs is water, either due to rainwater leaking in from above or to moisture vapour rising from the rooms below and condensing within the structure. This can cause decay in roof timbers, corrosion of fixings, movement in timber decking, loss of insulation efficiency, and deterioration and blistering of the roof covering. A flat roof may be said to have failed when moisture has penetrated the construction.

Flat roofs should be thus so designed that they do not allow ponding of water, although some degree of temporary flooding or ponding may be inevitable during heavy rain storm.

Due to the materials commonly used in flat roof constructions, for example bituminous products, bituminous felt, various metals, mastic asphalt etc, sunlight and heat as well as the structure can cause movement of certain parts of the roof construction.

All flat roofs should thus be designed to allow for movement due to the surface area they present to the elements and the materials they are constructed from. Movement is designed into the roof by allowing the top layer and waterproof layer(s) to move independently of the deck. This is accomplished using a separating layer not being secured physically to the deck. This also is a weakness of the construction because, if the movement is not sufficiently accommodated, then the waterproof layer(s) may form cracks which will allow moisture to penetrate the construction. Other failures can occur through the waterproof layer(s) being penetrated by falling debris or human error.

In cases where the flat roofs are thermally absorbent they are more susceptible to movement caused by expansion and contraction of the top layer due to the effect of sunlight and heat. Constant expansion and contraction may lead to faults in the form of micro-cracks which can allow moisture in between the roof layers and create moisture pockets. The result of the pockets is the bulging of the roof and can cause wrinkles in the roof surface or ponding. In addition, the micro-cracks can allow the penetration of rain water through the top layer.

In most cases a first indication that a fault exists is the appearance of staining, dampness or mould growth on a ceiling on the underside of the roof.

Once the existence of a fault in the flat roof is detected, the fault is generally treated by either repairing, refurbishing or replacing at least a section of the top layer and the waterproof layer(s) at a location

corresponding to the appearance of the staining on the ceiling. This requires favourable weather conditions for the work to be carried out.

If the water damage is a result of rainfall and there is not a sufficient break in the rainfall to allow the roof to be treated, significant damage to the structure may result.

Furthermore, due to the nature of the flat roof design and construction i.e. built up in a series of layers, the location in the ceiling of the staining identifying that there is a fault in the roof rarely corresponds to where the leak is actually located in the roof. This is because moisture/water can track its way through the construction layers and the appearance of moisture on the inside of the building, i.e. on the ceiling, only indicates failure and rarely does the appearance of moisture occur directly under the failure. Furthermore, water may track through the construction and present itself intermittently at different points some distance from the source of the roof failure giving the impression that there are multiple faults which may not be the case. The destruction process can be amplified by the continued heating and cooling of the roof wherein trapped moisture in the layers expands on heating and contracts on cooling. This cycle adds to further delamination of the construction, which may not be apparent from inside the building.

There is therefore a need for an improved method for treating a roof which mitigates the above mentioned problems. In particular one which provides an improvement to the hit and miss nature of current flat roof repair methods.

According to the invention, there is provided a method of treating a roof comprising the step of applying a gel to a roof comprising a fault defining a leak, said gel being adapted to at least partially block the fault in the roof. By means of the invention, a fault in the roof can be at least partially blocked thus reducing/limiting the damage that may result from the ingress of water through the waterproof layer.

The method provides a way of creating a seal, typically but not exclusively a temporary seal, in the roof which does not require favourable weather conditions for the treatment of the roof to be carried out. Thus the method of the invention can conveniently be utilised to create a temporary seal while waiting for favourable or ambient weather conditions or suitable budget requirements for the roof to be repaired, refurbished or replaced as required.

In addition, the method of the invention provides an improvement to the hit and miss nature of current flat roof repair methods. Conveniently the roof is a flat roof. Preferably the method further comprises the step of limiting the exposure of the gel to the atmosphere to maintain the gel. Once the gel has formed, the presence of moisture maintains the integrity of the gel. Provided moisture is present, the seal within the structure is maintained and it becomes self perpetuating.

Limiting the exposure of the gel to the atmosphere will help retain the gel and prevent it from drying up which will affect the gel's ability to at least partially block the fault in the roof.

In exemplary embodiments, the step of limiting the exposure of the gel to the atmosphere to maintain the gel comprises the step applying a plastic film, plastic sheet or tarpaulin to a section of the roof where the fault is located.

In exemplary embodiments of the invention, the method is utilised to stop a leak in the roof.

In exemplary embodiments of the invention, the method is utilised to identifying the location of a leak in the roof.

Thus a user can ascertain the vicinity of the roof where the top layer and waterproof layer(s) need to be repaired, refurbished or replaced in order to restore the integrity of the roof.

Preferably the location of the leak is identified after a period of time has lapsed following the application of the gel to the roof. Preferably the method further comprises the step of utilising a first liquid to treat the fault, said first liquid being adapted to carry said gel in a direction towards said fault and to flow towards and through the fault in the roof. Preferably the gel comprises an indicator means adapted facilitate identification of the location of the gel when applied to the roof.

The indication means allows a user to more readily indentify the position of the gel after it has been applied to the roof.

In exemplary embodiments of the invention, the indicator means is adapted to produce a trail indicating the flow-path of the gel carried by the first liquid. This allows a user to trace the moisture passage through the roof. This means that a user can follow the path of the gel carried by the first liquid. This is particularly advantageous in cases where the flow rate of water through the fault is slow as a user can check the movement of the gel towards the fault after a period of time has lapsed and does not need to constantly monitor the gel movement.

In addition, this allows the user to confirm that the fault has been located by the gel by checking the trail after an interval of time as the trail will not change once the gel has reached the fault.

The indicator means may comprise a dye or an ink or other means.

It is proposed that the gel will have a traceable dye or ink within the composition of the material. The dye or ink may be colour specific or be identifiable under a specific light source such as ultra violet. This may be accomplished by addition of a dye or ink compound to the gel. The dye or ink is preferably a slow release dye or ink which will slowly release dye or ink into a body of the first liquid after the gel is placed therein.

The gel may be adapted to increase in volume when placed in the first liquid. It is preferred that in use the gel has a viscosity of at least 10,000 centipoise at room temperature. Preferably the gel, in use, has a viscosity of between 10,000 to 20,000 centipoise at room temperature. Ideally the gel, in use, has a viscosity of between 14,000 to 16,000 centipoise at room temperature.

In exemplary embodiments of the invention, the gel may be a starch based gel, a talc based gel, a methylcellulose based gel, a

hydropropylmethylcellulose based gel, a carboxymethylecellulose, a sodiumcarboxymethylecellulose based gel or a combination thereof. The gel composition may further comprise clay.

In exemplary embodiments of the invention, the gel is made up of a gellant mixed with the first liquid. The gellant is preferably soluble in the first liquid.

Where the gel is made up of a gellant mixed with the first liquid, the location of the leak is identified by following the formation of the gel. In exemplary embodiments of the invention, the method of treating a roof may further comprise the step of preparing said gel by mixing a gellant with water prior to applying the gel to the roof. The gellant may be in granular form, powder form, flake form or pellet form.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example

"comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. There now follows a description of preferred embodiments of the invention, by way of non-limiting example, with reference being made to the accompanying drawings, in which:

Figure 1 is a schematic view of a section of a building comprising a flat roof;

Figure 2 is a partial cross-sectional view of a section of a flat roof having a fault; Figures 3 to 6 show the formation of a gel at a fault in a roof in accordance with an embodiment of the invention; and

Figures 7A to 9B show the flow of a gel towards a fault in a roof in accordance with another embodiment of the invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood that the drawings and detailed description thereof are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the scope of the invention as defined by the appended claims. Further, although the invention will be described in terms of specific embodiments, it will be understood that various elements of the specific embodiments of the invention will be applicable to all embodiments disclosed herein. In the drawings, the same features are denoted by the same reference signs throughout.

Referring to figure 1 , an embodiment of a section 1 of a building having a flat roof 10 is shown.

In the embodiment shown, the flat roof 10 is in the form of a cold-deck roof arrangement, as known in the art. The flat roof 10 comprises a deck 12 defining a surface onto which a waterproof layer (not shown) is overlaid and top layer 16 is positioned on top of the waterproof layer. A layer of insulation 18 is positioned underneath the deck 12 with a cavity space 20 defining a ventilation air gap located between the insulation 18 and the deck 12. The insulation 18 sits above a plasterboard ceiling 22. In the embodiment shown, the roof 12 further comprises a structure for supporting the roof components in the form of a plurality of roof joists 24 extending across the ceiling. The roof 10 also further comprises a gutter 26 for facilitating the diversion of rainwater away from the roof 10.

The materials and dimensions of the components of the roof will be dependent on the requirements for the roof.

For example, in an exemplary roof arrangement, a standing seam copper top layer is underlain with a felt waterproof membrane. The deck 12 is in the form of a 19mm thick plywood deck and a 50mm ventilation air gap is positioned between the deck 12 and the insulation 18. The insulation 18 is 1 10mm thick roof insulation and is positioned on top of a 12.5mm foil backed plasterboard ceiling 22. The roof joists 24 are 50mmx200mm softwood roof joists spaced at 450mm intervals which support the roof and ceiling. While a cold-deck roof arrangement has been described above, the invention is not limited thereto but can be applied to other roof

arrangements as known in the art. Referring to figure 2, a partial cross-sectional view of a section of a flat roof arrangement having a fault is shown. Only the top layer 16, the waterproof layer 14 and the ceiling 22 are shown in figure 2 for clarity. While the top layer 16 and waterproof layer 14 are shown as being separate entities, it will be understood that the waterproof membrane may define the top layer.

The roof comprises a fault 28 which is in the form of a micro crack defining an aperture by which water may pass from the top layer 16 and waterproof layer 14 to the ceiling 22.

The ingress of water through the fault will, after some time, result in a visible indication 30 such as a staining, dampness or mould growth on the ceiling 22. The indication 30 may be located directly underneath the fault 28 or located at some distance from the fault 28 as shown in figure 2.

Conveniently, once the indication 30 appears or as part of routine maintenance of the roof, a user may utilise the method of treating a roof in accordance with the invention.

A first embodiment of a method according to the invention will now be described with reference to figures 3 to 6. The method comprises the step of applying a gellant 38 to the roof. The gellant 38 being adapted to produce a gel which is adapted to at least partially block the fault 28 in the roof.

The gellant 38 may be in granular, powder, flake or pellet form and comprise a starch, a talc or a methylcellulose base. The gellant 38 on contact with liquid forms a solution which on increased concentration forms a gel which also expands on increased concentration.

In a preferred embodiment, the gellant is a water soluble powder which when combined with water forms a gelatinous solution, which as more powder is added to and dissolved in the water increases the concentration the gelatinous solution and changes its state from liquid to a gel.

In another embodiment, the gellant is in the form of a water soluble pellet which is adapted to slowly dissolve in water to form the gelatinous solution.

An example of a suitable gellant is one comprising methylcellulose, carboxymethycellulose (CMC 45) and starch flour in a 1 :1 :19 weight ratio. Another example of a suitable gellant is one comprising methylcellulose, carboxymethycellulose (CMC 45) and talc in a 1 :1 :19 weight ratio.

In use, a quantity of the gellant 38, for example in powder form, is applied to a body of water 36 on the roof (see figure 3). The body of water may be in the form of rain water on the roof soon after rainfall or if the rainfall is light, during rainfall. This may be in the form of puddles known as ponding. If the rainfall is not heavy enough to provide a sufficient quantity of the body of water 38 or there is no water on the roof, water can be run on the roof by a suitable means, with a hose for example, to achieve the sufficient quantity.

The body of water 36 needs to be of sufficient volume that it would flow through the fault 28 in the roof. Due to the size of the fault 28, the flow of water through the roof will be by means of capillary action, which will draw the water through the fault into the roof structural layers. The quantity of gellant 38 that needs to be applied to the body of water should be sufficient to produce a gel having a viscosity of 10,000 to 20,000 centipoise at room temperature, preferably between 14,000 to 16,000 centipoise at room temperature, in use.

The release of the gellant 38 into the liquid to form the gel 38 is to be controlled so that initially a light solution is formed which over time becomes more concentrated to finally form the gel 38.

In this respect, the gellant 38 further comprises an inhibitor which controls the rate of release of the gellant 38 into the liquid.

The inhibitor is designed to release the gellant such that its rate of decay in the water increases exponentially with time, for example decaying at 2%-4%-8%-16% etc. over time.

When placed in the body of water 36, the gellant 38 will mix with the water and produce one or more pockets of a gelatinous solution 42 within the body of water having a higher viscosity that the water.

The pocket(s) of the gelatinous solution 42 will be carried by the body of water 36 in the direction of the fault 28, as shown in figure 4, as the body of water 36 flows through the fault 28.

When the pocket(s) of the gelatinous solution 42 reaches the fault 28, it will start to pass through the fault but due to the viscosity of the gelatinous solution 42 it will begin to create an obstruction in the fault aperture (see figure 5). The pocket(s) of gelatinous solution 42 will coagulate over time to form a gel 32 which creates a temporarily seal in the fault 28 (as shown in figure 6). In cases where more than one pocket of gelatinous solution 42 is formed by the application of the gellant 38 into the body of water 36 it is possible that at least two pockets will combine with each other prior to reaching or within the vicinity of the fault.

The location of the leak is thus identified after a period of time following the formation of the gelatinous solution 42 or gel 32 on the roof.

Referring to figures 7A to 9B, a second embodiment of a method according to the invention is shown. In this embodiment, rather that the application of a gellant to the roof as in the first embodiment, the method comprises the application of a gel 32 to the roof which is adapted to decrease the porosity of the fault 28 in the roof.

The gel has a viscosity of 10,000 to 20,000 centipoise at room

temperature, preferably between 14,000 to 16,000 centipoise at room temperature, and is a starch based gel or a talc based gel comprising methylcellulose, carboxymethylcellulose and water in the ratio shown in tables 1 and 2.

Table 1 - Composition of starch based gel Material

Talc 19 g

Carboxymethylcellulose 1 9

Methylcellulose g

Water 79 ml

Table 2 - Composition of talc based gel The gel may be pre-formed or may be made up by a user for application to the roof. If pre-formation of the gel is require, the user simply mixes a gel forming substance, i.e. a gellant, with a liquid such as water. The gel forming substance may be in granular, powder, flake or pellet form. In use, the gel is applied to the body of water 36 on the roof. As in the first embodiment, the body of water 36 needs to be of sufficient volume that it would flow through the fault 28 in the roof.

When placed in the body of water 36, the gel 32 will be carried by the body of water 36 in the direction of the fault 28, as shown in figures 8A and 8B, as the body of water 36 flows through the fault 28.

When the gel 32 reaches the fault 28, it will start to pass through the fault but due to the viscous nature of the gel 32, will create an obstruction in the fault cavity and create a temporarily seal in fault 28.

The location of the leak is thus identified after a period of time following the application of the gel 32 to the roof. In the first and second embodiments, once the gel 32 has temporarily sealed the fault 28, the drying out of the faulted area is to be avoided as the presence of moisture is required to maintain the integrity of the repair. If circumstances allow, retention of the humidity within the roof structure may be achieved by covering the designated fault over using an enclosed plastic film, plastic sheeting or tarpaulin, this is an additional measure which may be added to achieve the results sought and is not necessary. The use of a plastic film, plastic sheet or tarpaulin (not shown) to cover the area deemed to be leaking, and hence the gel 32 in the region of the fault, will limit the exposure of the gel 32 to the atmosphere in order to maintain the gel 32 and prevent it from drying out. In order to facilitate the identification of the location of the gel 32 or gelatinous solution 42 in the body of water 36, it is preferable that the gel 32 or gellant 38 comprises an indication means.

The gel 32 or gellant 38 may be luminous and/or may comprise a high colour contrast, fluorescent properties, a dye or ink compound which defines the indication means.

In embodiments where the gel 32 or gellant 38 comprises a dye or ink compound, the dye or ink can be a slow release dye or ink. As such the slow release dye or ink will produce a trail indicating the flow path 34 of the gel 32 or gelatinous solution 42 carried by the water body 36. In this way, a user can return to the roof after a suitable amount of time and readily identify the position of the gel and easily ascertain whether the gel has reached the fault by seeing whether further movement of the gel 32 or gelatinous solution 42 has occurred. While not essential, the gel 32 or gellant 38 may further comprise other components such as a hardener, a fungicide, wood preservatives, cleansing agents and/or flow enhancing chemicals.

While the method of treating a roof in accordance with the invention has been described with reference to application of a gel or a gellant to the roof. It is envisaged that the roof can be treated by spraying a gelatinous solution having the characteristics described above to the surface the roof. This will provide a preventive measure which will seal any faults that may exist prior to the onset of rainfall which may otherwise cause the ingress of water into the roof structural layers.