|Publication number||USRE39223 E1|
|Application number||US 09/425,271|
|Publication date||Aug 8, 2006|
|Filing date||Oct 21, 1999|
|Priority date||Sep 4, 1989|
|Publication number||09425271, 425271, US RE39223 E1, US RE39223E1, US-E1-RE39223, USRE39223 E1, USRE39223E1|
|Original Assignee||Tma Corporation Pty Ltd|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (48), Non-Patent Citations (4), Referenced by (6), Classifications (16), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This is a Continuation of U.S. Ser. No. 08/859,561, filed May 20, 1997, which is a Reissue Application of U.S. Pat. No. 5,417,017, which issued May 23, 1995 from U.S. Ser. No. 08/040,305, filed Mar. 30, 1993, which is a Continuation-in-Part application of U.S. Ser. Nos. 07/575,908, filed Aug. 31, 1990, now abandoned, and 07/825,299, filed Jan. 23, 1992, now abandoned.
This invention relates to the control of termites in relation to buildings and other structures and in particular to achieving such control without the use of harmful chemicals.
The most popular procedure for providing a barrier to the access of termites to buildings or other structures supported in or on the ground is to saturate the ground beneath or around the structure with appropriate chemicals, to kill any existing termites, and to provide a residue of the chemical within the ground which will remain effective for many years against the passage of termites therethrough to the structure. It has been proposed in published patent specifications to provide a mat of fibrous or absorbent material to be laid below the foundations of a building with the fibre or porous material saturated with, or containing an appropriate chemical which will kill termites that attempt to pass therethrough. Refer to published Australian Patent Application Nos. 85176/82, 11412/83, 16980/83 and 21934/84.
These methods of termite control have the major disadvantage as the chemicals are usually of a composition that is considered highly dangerous to humans and thus constitute a hazard to the people applying the chemicals and to other people in the vicinity. Under some atmospheric conditions, the chemicals can be carried considerable distances from the area where they are being applied. Thus people unaware of the presence of the chemicals, and thus not alerted to take protective action, may also be exposed to the potential danger of the chemicals used to control termites. The danger continues to exist after the initial application of the chemical so long as the chemical remains effective against the termites.
Also, as it is necessary to establish a high concentration of the chemical in the ground beneath where the building is to be built in order to obtain the required period of protection against termite entry to the building, leaching of the chemical will occur over time. This leaching will naturally reduce the effectiveness of the chemical as a barrier to the termites. As the chemical in many instances is initially placed beneath a concrete slab upon which the building is erected, it is very difficult to apply further chemical to replace that removed by the leaching and so maintain an effective barrier. Even more importantly, chemicals leached from the ground beneath the building are carried by the leaching water into other areas where it may be hazardous to humans, animals or crops. Also the leached chemical can enter rivers, streams or lakes or underground water catchments which can potentially spread the chemicals over a very wide area thus increasing the potential exposure to the chemical. It will also be appreciated that the chemicals leached from building sites over a relatively wide area can collect in a single river, stream or other catchment, thus resulting in an accumulation of chemicals that break down very slowly.
Many buildings, particularly homes, are built on a slab of concrete and although termites can normally not penetrate concrete, cracks frequently develop in the concrete thus permitting the passage of termites therethrough into the building. Even when the cracks are of a fine nature, they do provide the facility for the termites to burrow through the concrete by secreting materials which will break down the concrete along the fine cracks and thus permit the termites to burrow therethrough.
Also, in buildings erected on a concrete slab, it is common practice to provide pipes or conduits that extend through the concrete slab, such as water and waste pipes. As the concrete is cast in situ about these pipes or conduits, a small opening often develops about the pipe or conduit due to shrinkage of the concrete during curing.
These openings also provide access for termites through the concrete into the building structure. Thus even where a building is erected on a concrete slab, the ground beneath the slab must be treated with substantial quantities of chemicals to prevent access by termites to these openings.
It has also been known to use sheet metal as a barrier to termites such as galvanized steel plates on the top of stumps that support a building. Although this may be effective and commercially viable in relation to a building supported on stumps, it is expensive and has installation problems when considered in respect to a building supported on a concrete slab. Sheet metal is difficult to join on-site in a manner to exclude passage of termites through the joint. Also, if the metal sheet is sufficiently strong to prevent accidental puncture by workman traffic on-site, it is then difficult to bend and shape to the required contours to fit with the building structure in a manner to provide an effective termite barrier. It would also be difficult to achieve an effective seal around pipes or conduits that must pass through the sheet.
Sheet metal, including stainless steel, as proposed in French Patent Application No. 79 04240 (Publication No. 2453952) is used to provide a barrier to termites travelling up a wall to enter a building in a manner analogous to a metal plate on a building stump. However, that sheet is preformed for a specific installation and is not appropriate for on-site construction to a range of shapes and configuration with the ability to maintain the integrity of a barrier against the passage of termites.
In addition to buildings, termites attack a wide range of structures and equipment including wooden poles and other wooden structures, underground cables and conduits made of a range of materials that will be attractive to termites. The only effective protection for such structures are chemical treatment or solid metal barriers that are resistant to termite attack.
It is therefore the object of the present invention to provide a barrier that will inhibit the passage of termites such as into a building or structure, the barrier being both effective and avoids the use of chemicals that are harmful to humans and/or the environment.
With this object in view there is provided by the present invention an improved termite barrier which is substantially resistant to termite chewing and corrosion, the termite barrier comprising a mesh sheet formed of a material resistant to breakdown in the environment of use and substantially resistant to termite secretions, said material having a hardness of not less than about Shore D70 for resistance to termite chewing, the pores of the mesh having a linear dimension in any direction less than the maximum linear dimension of the cross section of the head of the species of termite to be controlled.
Conveniently the pores of the mesh having a linear dimension in at least one direction, less than the minimum lineal dimension of the cross section of the head of the species of termite to be controlled. Preferably, the pores in the mesh am polygonal with a maximum diagonal dimension less than the maximum linear dimension of the cross section of the head of the species of termite to be controlled.
Termites of the species which attack wood, timber or the like are characterised by having a head formed of a hard substantially nondeformable structure. The body of these termites is a relatively soft and weak material. Also these termites have a head which is of substantially larger cross sectional dimensions than any other part of their body. Accordingly the head cross sectional size determines the ability of the termite to pass through an opening or passageway such as may exist in any form of termite barrier.
It is also known that termites secrete a liquid saliva or material which is capable of breaking down the physical structure of many materials into at least particles of a size that can be transported by the termites so as to facilitate the formation of a passage for the termites to pass through. The secreted material includes, amongst other components, acids such as formic acid.
The mesh sheet can be laminated with a flexible plastic sheet or sandwiched between two separate sheets.
Alternatively the mesh may be embedded in one plastic sheet, preferably with both sides of the mesh sheet covered by the plastic material. The combining of the mesh sheet and the plastic provides protection of the mesh sheet against damage that may cause displacement of the strands forming the mesh, with resultant enlargement of the openings or pores of the mesh in a specific area thereof to a size to permit the passage of the termites therethrough.
It is also to be appreciated that it is normal practice to provide a sheet of plastic material beneath the concrete slab upon which a building is to be erected to provide a barrier against the entry of moisture through the concrete into the building. Accordingly, by incorporating the mesh sheet with or into a plastic sheet, the resulting assembly can perform the two functions of providing a moisture and a termite barrier.
In practical application of the termite material a continuous layer thereof is positioned beneath an underside of the slab extending to a perimeter of the slab in all directions and upwardly about the perimeter of the slab to a distance above the slab and above the ground level adjacent thereto.
Another application is in a building structure erected on a ground level or near ground level concrete slab, and having a non integral termite resistant adjacent structure and a strip of the termite barrier material arranged with the respective marginal edge portions along the opposite longitudinal edges of the strip integrally secured to the slab and the adjacent structure to establish integrity of the connection between the slab and the adjacent structure against the passage of termites.
Preferably the mesh is woven from fine stainless steel wire or filaments of the appropriate material, such as stainless steel, that is resistant to corrosion by most materials that the mesh will be in contact with or associated with during its use in the termite barrier. In particular, the stainless steel resists rust through contact with moisture, and resists attack by most acid materials, including formic acid and other constituents of the secretion released by termites. However, it is to be understood that wires, strands or filaments of other materials may be used to produce the mesh sheet provided the material has the required resistance to breakdown when exposed to the environment and materials present in the ground and to termite attack, and is sufficiently hard that the particular species of termites can not chew through the strands or filaments. Other materials may be fibres of ceramics, glass or hard plastics.
It is known that the physical dimensions of termites vary from species to species and that in different areas of the world, different species of termites are predominant. Accordingly, the actual size of the pores of the mesh will be determined by the particular termite or range of termites to be controlled in the particular area where the mesh is to be used.
In the area around Perth, Western Australia, the most common and dangerous termites are of the Coptotermes family which have a head of a generally circular cross sectional somewhat flattened shape, as shown in
The wire of filament may be of any convenient commercial size and typically may be in the range of 0.1 to 0.2 mm in diameter. The wire of filament may be of cross-section is preferred and more readily commercially available in the manufacture of mesh. The mesh may also be produced by stamping or punching holes of the required shape in sheet or film of metal or other suitable material of an appropriate thickness.
In most species of termites there are worker termites and soldier termites, the latter having larger heads than the worker termites in some species, but not all. It is thought to be normal for the soldier termites to lead or at least travel with the invention. Thus it is believed that if the mesh has pores of a size to prevent the passage of the soldier termites, this would be effective in inhibiting the worker termites from passing alone through the mesh. The workers are the ones that cause the damage and must be stopped by the mesh.
The plastic material forming the sheet with which the mesh sheet can be laminated or embedded in, is conveniently PVC, but may be of any other suitable plastic which will provide a moisture barrier and will not deteriorate and break down when buried in the ground for the normal life expectancy of termite barriers which may be of the order of 15 to 30 years.
Conveniently, the termite barrier is produced in sheets of any convenient size and may be produced in a form of roll of a width of the order of 5 to 10 meters.
The advantages of the termite barrier as proposed above are principally that there are no harmful chemicals used in the creation of the barrier, the barrier will have an effective life commensurate with the life of the building. Further, the barrier can be conveniently transported and applied without the level of precautions required when handling pesticides or other chemicals and with a minimum of skill. Further as the barrier is in the form of a mesh, it is substantially more flexible and easily worked as by cutting, contouring and shaping, particularly in comparison with solid sheet metal.
The invention will be more fully understood from the following description of the termite barrier as applied to buildings and other uses and as illustrated in the accompanying drawings, wherein:
Referring now to FIGS. 1 and 2a-2c of the drawings, the termite barrier is in the form of a woven mesh 10 made of corrosion resistant stainless steel wires or filaments such as 304 grade stainless steel. The termite barrier may also include a flexible moisture impervious plastic sheet 121 formed to the woven mesh 10. Preferably, both sides of the woven mesh 10 are covered by a plastic sheet 121. The woven filaments form a series of pores or openings 15 in the mesh which are of a generally rectangular shape with the distance between the two more closely spaced sides 16 of the rectangle and the diagonal thereof is less than the maximum cross sectional dimensions of the head of the species of termite in respect of which the mesh is to form a barrier (FIG. 2c). For instance, the soldier termite of species Mastotermes darwiniensis, of northern Australia, has a maximum head width of 3.25 mm. To form a termite barrier for Mastotermes darwiniensis, the distance between the two more closely spaced sides 16 of the rectangle and the diagonal thereof should be 3.25 mm or less.
Referring now to
After the footings 25 have been poured and cured, an integral sheet of termite barrier mesh 30 is laid over the complete area where the slab 23 is to be poured with portion of the mesh overhanging beyond the footing 25 as will be referred to further hereinafter. When the mesh 30 is laid it is contoured to closely follow the contour of the ground including following the contour of any trenches or depressions in the ground, such as are required to accommodate the increased thickness areas 26 and 28 of the concrete slab. Because the termite barrier is in the form of a wire mesh, it can be readily deformed to follow these contours, and can be readily folded where there is excess material resulting from a change in the contour of the surface over which it is being laid. Where a pipe or duct such as indicated at 31 is required to pass through the slab 23, an appropriately located aperture is cut in the mesh 30 and the edge of the mesh clamped about the pipe or duct as hereinafter further described with reference to FIG. 4.
For convenience in handling, the mesh is produced in rolls of a convenient width such as 5 m, and the mesh is laid in position with the edges of adjacent strips overlapped and secured together in a multi fold lap-type joint wherein as each fold is made it is hammered or rolled flat throughout its length to provide a secure and permanent join that is termite-proof.
After the strips of mesh have been placed in position and effectively secured along the overlapping edges, and the form-work for the concrete slab 23 is in position, the slab is poured in the conventional way with conventional steel reinforcement therein and a moist barrier sheet therebeneath (not shown). After the elapse of the appropriate curing time, the commencement of the erection of the external double brick wall of the building can be undertaken. In regard to the double brick wall construction as seen in
There is thus formed a complete barrier in the perimeter double brick wall which is continuous with the barrier beneath the concrete slab to prevent the entry of termites into the interior of the building.
As an alternative, as shown in
Where a conduit, such as 31 in
Preferably the flange 35 is formed to project upwardly from the normal level of the barrier mesh as shown in
Referring now to
Following completion of the positioning of the perimeter beams 12 in place upon the footings, the area bounded by the beams is prepared for pouring of the concrete slab by the laying down and compacting of a bed of stones as indicated at 13 prior to the pouring of the full slab. Also prior to pouring of the slab, a continuous strip 15 of the termite barrier material is arranged so one marginal edge portion 16 is applied to the internal face of the beam 12 by appropriate mechanical fixings such as concrete nail and is overlayed by an adhesive cement layer as indicated at 17. After curing of the adhesive cement, the concrete floor slab 19 is poured and during such pouring the other marginal edge portion 18 of the barrier material strip 15 is embedded in the concrete slab.
The concrete of the slab may extend up to and abut the internal face of the beam 12, thereby also encasing the marginal portion 16 of the termite barrier strip that is adhered to the beam, or in alternative structures, an expansion gap, may as indicated at 22 be left between the perimeter edge of the slab 18 and the adjacent beam 12. Where such an expansion gap is left, as seen in
It is also to be understood that the beam 12 as shown in
The above description of the installation of the termite barrier strip between a beam or wall and a slab may also be applied to providing an effective termite barrier between an existing concrete member and a newly cast member which may be functioning as an extension of an existing structure. In such circumstances, the same technique and layout as above discussed with respect to the beam and slab, may be applied to extending an existing slab.
Referring now to
There is shown in
It is to be understood that the term bricks or blocks includes building blocks of a range of materials including natural stone, rock, concrete and the brick or block may be of steel or aluminum in block or sheet form.
As previously referred to with respect to
In the previous description of the practical application of the present invention, reference has been made to using adhesive cement to secure a marginal edge portion of the barrier strip to an adjacent member which may be concrete or building bricks or blocks. The nature of the adhesive cement is a mixture of conventional cement and fine sand to which there is added a proprietary cement adhesive agent, such as that marketed in Australia under the Registered Trade Mark BONDCRETE. The sand used in the adhesive cement is selected so that it is sufficiently fine that the individual particles will freely pass through the openings in the mesh of the barrier strip thereby ensuring an effective bond between the barrier strip and the adjacent structural member and to prevent the possible formation of areas which are not adhered and therefore potential passages for termites.
The termite barrier material used as above described in relation to building may also be used as a termite barrier in respect of a wide range of structures incorporating material which is subject to attack by termites. One such additional application is around the portion of a post or like member which has the lower portion thereof buried in the ground. It is customary to treat the lower portion of such posts with appropriate chemicals to inhibit attack by termites, however, such chemicals have a limited effective life and environmental disadvantages. The termite barrier material of the present invention can be formed into a sleeve or pocket 38 closed at one end 39 and fitted over the portion of the post to be buried in the ground with the closed end lowermost as shown in FIG. 11. The sleeve is of sufficient length to project at least 10 to 20 centimeters above the ground level when the post is erected.
When the barrier mesh is to be used for this purpose, it may be initially woven in a tubular form and then cut to the requisite length for each particular application. The individual lengths of the tubular mesh are then folded at the bottom end to form an effective closure. This closure may be formed by flattening a portion of the end of the tube and then forming multiple folds therein with the folded portion being subsequently pressed or hammered flat to form a multi lapped joint which is not penetrable by the termites.
When the mesh is not produced in a tubular form, a flat piece of mesh may be rolled to form a tube with the respective edges of the strip folded in a multi lapped Joint which is again rolled or hammered flat.
In the above description the application of the termite barrier material to the lower end of a post it is to be understood that the same construction of termite barrier can be used on any member which is to be buried in the ground, whether it is in the nature of or forming the function of a post or for any other purpose.
Another use for the termite barrier material is in protecting cables, particularly underground cables which incorporate a material which is susceptible to attack by termites. Such cables normally are of a construction as shown in FIG. 10 and have an outer protective covering 40 of a suitable material in addition to the wires or other elements 41 of the cable, such as electrical or optical cable, and the normal insulation or other coatings or wrappings 42 in which they are located.
It is known to weave in situ about the core of such cables fabric or wire reinforcing materials and it is proposed by the present invention that there also be woven about such cable cores a mesh of stainless steel wires or filaments 43 of the required dimensions to form a barrier against the passage of termites into the cable. If the termite barrier is not woven in situ about the core of the cable, then a wrapping of the barrier material of the required construction may be fitted about the cable with a longitudinal seam being formed by a lapped joint in the manner previously discussed. The termite barrier is located in or beneath the outer tough covering normally provided on such cables, as an alternative to about the exterior as shown in the drawing.
The termite barrier as previously described may be used in many other applications in addition to those described with reference to the accompanying drawings without departing from the present invention.
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|U.S. Classification||52/101, 52/834, 52/515, 52/250, 174/107, 52/741.3, 52/292, 245/8|
|International Classification||A01M1/00, E04B1/72|
|Cooperative Classification||E04B1/72, A01M29/34, A01M1/24|
|European Classification||A01M29/34, A01M1/24, E04B1/72|
|Sep 20, 2006||FPAY||Fee payment|
Year of fee payment: 12
|Dec 5, 2006||CC||Certificate of correction|