AU2003203815A1 - Granular Termite Barrier - Google Patents

Description

Granular Termite Barrier This invention relates to the protection of buildings from subterranean termites and is particularly concerned with termite barriers for use with concrete slab-on-ground buildings such as those having a masonry veneer cladding.

Subterranean termites typically build nests just beneath the soil surface and forage, principally for cellulose containing material, for distances which can reach hundreds of meters from their nests. Termite damage to buildings, particularly residential buildings can be as many as one building in five in some parts of Australia, costing the community many tens of millions of dollars annually in the repair of the affected timber. As a result, the Australian Building Code has made it compulsory for all new buildings to incorporate suitable termite barriers. The current Building Code is laid down in Australian Standard 33460.1-1995. This standard specifies three permissible systems for protecting concrete slabs from termite penetration. The systems comprise the use of stainless steel mesh, graded stone or chemicals.

Chemicals soil barriers have recently come under attack by environmentalists on the basis that their toxicities may be harmful to man. This has lead to the banning of conventional chemicals and the use of more environmentally friendly materials. Unfortunately such materials are less effective and may have no effect whatsoever after as little as twelve months from application.

Graded stone barriers must satisfy a large number of criteria to be effective. The stones must be of crushed igneous or metamorphic origin, be from a sound source, have a minimum sg of 2.52, and be graded and shaped so that the termites cannot lift them or penetrate their voids. A typical product meeting these requirements is GRANITGARD', which is granite stone, supplied by CSR Readymix, a Divisional of CSR Limited.

The problem with such products, however, is that they cannot effectively be used on sloping ground surfaces, supply in many parts of Australia is difficult, and they are relatively expensive.

Stainless steel mesh barriers are consequently now in widespread use. These barriers are, nevertheless, not without their drawbacks. Apart from their relatively high costs, which cannot be avoided, there are particular problems when it comes to their installation at the perimeter of concrete slabs having masonry veneer walls.

The commonly used method comprises parging an inner edge of the mesh to be perimeter of the slab and extending the mesh out under the row of bricks which I substantially level with the slab. The parging material is an adhesive, which is required to be termite resistant, form a strong bond between the mesh and the concrete, and be durable over the life expectancy of the building. In practice, however, it is difficult to form a proper seal with the parging material due to the relative movement between the bricks and the concrete slab due to different rates of drying, and expansion and contraction taking place. The integrity of the seal is therefore frequently broken and regions for termite entry are provided.

One way of overcoming the previous problems is the subject of Australian Patent Application No.

64411/96. This patent application describes a physical termite barrier for incorporating in the perimeter of a concrete slab and an adjacent masonry wall. It comprises a continuous sheet of termite resistant material, selected from sheet metals and sheet plastics materials, which has a substantially Z-shaped profile incorporating movement resisting deformations. Curved regions are provided where the three planes of the sheet meet which function to assist the barrier to resist sheer fracture when the barrier is set in the concrete slab and masonry wall. The barrier is arranged in situ with one end planar section extending substantially horizontally into the concrete slab, inwardly of the perimeter, the other planar end section extending in the masonry mortar over the upper surface of the upper row of perimeter bricks/blocks, and the intermediate planar section extending perpendicularly within the slab adjacent the perimeter thereof.

While such a barrier is an extremely effective termite barrier for the life of the building, it has the disadvantage that if the adjacent masonry slab is not built to the correct tolerances, then the barrier will not be positioned in the most effective location within the mortar joint. Furthermore, the relative inflexibility of the barrier can give rise to other minor difficulties in the handling and laying of the product.

Another way of addressing the previous problems is the subject of Australian Patent Application No.

64430/99. This patent application describes a membranous termite barrier which is adapted to extend between the mortar course of a masonry wall and an adjacent concrete slab. The membranous termite barrier comprises a matting impregnated with a termite resisting product. The matting is typically in the form of a longitudinally extending strip which can be rolled out over an upper coarse of the masonry wall (which at this stage of construction is only a few courses high) and can be adhered to the adjacent concrete slab. The edge of the matting strip which is adapted for location on the upper coarse of the masonry wall, within the mortar joint, preferably has an associated inspection band welded or adhered along its edge in order to enable the mortar joint to be racked without destroying the edge of the matting, and to ensure that the termite resistant product embedded therein is not lost by evaporation to the air or diluted by moisture absorption from the air.

However a problem with the matting is the difficulty in providing a suitable termite proof adhesive joint with the concrete slab and also the fact that installation can be tedious.

It is therefore an object of the invention to provide a termite barrier which does not have any of the aforementioned disadvantages and which provides the public with a useful alternative.

According to one aspect of the present invention there is provided a termite barrier comprising an absorbent granular material impregnated with a nontoxic termite resistant solution.

By "non-toxic" is meant that the solution is not toxic to mammals, particularly humans.

By "termite resistant" is meant that the solution is toxic to termites insofar as the termites die immediately or shortly after contact with the solution.

Suitable non-toxic termite resistant solutions include, but are not limited to, termiticides such as pyrethrums, chlorpyrifos, chlorfos, mixtures of natural oils and natural timber saps, and like materials.

Additional additives and/or diluents may also be included in such solutions.

Absorbent granular materials include any particulate material which has the ability to absorb the non-toxic termite resistant solution and be substantially non-reactive therewith. Preferred such materials are naturally occurring products such as clays and pumice stones which have been crushed and sized to produce a mean particle diameter within the range of approximately 0.05 to 5mm, preferably about 1.0 mm; and artificial products such as absorbent polymers, carbons and the like which are pre-formed to the desired particle size.

A second aspect of the invention relates to a method of installing a termite barrier in a cavity of a slab-on-ground building having a masonry veneer cladding.

The method comprises the step of filling the cavity with an absorbent granular material impregnated with a nontoxic termite resistant solution, to the depth of a single course of brickwork.

Additional steps can be provided to enable means for recharging the absorbent granular material with the non-toxic termite resistant solution. One such step includes providing an access port from the exterior of the building to the absorbent granular material. The access port can be a tube having a cap on the outer facing end which is located just below the upper level of the first course of bricks. Associated means may be necessary to prevent significant disturbance of the absorbent granulated material when the non-toxic termite resistant solution is admitted to the cavity under high pressure. This can comprise, for instance, a deflection plate spaced from the inner end of the tube which absorbs the force of the jetted solution and lets the non-toxic termite resistant solution percolate down through the absorbent granulated material. This requires a large number of access points around the perimeter of the building slab to achieve complete recharging.

Advantageously, the use of a granular material as a termite barrier means easy and quick installation, and means that the integrity of the barrier is maintained should there be any shifting or cracking in its vicinity as the granules will move to accommodate such changes.

Whilst the recharging system described above requires a large number of distribution points, this may be advantageous in applications where access is relatively unrestricted. However, there are applications where it would be desirable to provide a system for recharging the granular material with termite resistant solution which is more efficient and less time consuming than the previously described method.

According to one aspect of the present invention there is provided a termite barrier comprising an absorbent granular material impregnated with a nontoxic termite resistant solution, which granular material is located within the lower region of a cavity of a masonry-clad concrete slab-on-ground building, the improvement comprising a retriculation pipe also located in the lower region of the cavity, which is designed and arranged to deliver the non-toxic termite resistant solution to the absorbent granular material.

According to another aspect of the present invention there is provided a method for recharging an absorbent granular material located in the lower region of the cavity of a masonry clad concrete slab-on-ground building, with a termite resistant solution, which method comprises passing the termite resistant solution into a reticulation pipe located in the lower region of the cavity so that the termite resistant solution percolates out through the retriculation pipe wall into the absorbent granular material.

The retriculation pipe can be laid above, on or within the absorbent granular material. For ease of construction and maximum effectiveness, it is preferably laid on the surface of the absorbent granular material against the vertical wall of the concrete slab.

The retriculation pipe can be such as to have a single inlet for the termite resistant solution but the actual number of inlets will be determined by the size of the building's perimeter and the number of discontinuities therein. However notwithstanding that there may be several inlets, this number will still be significantly fewer than the number of inlets in the aforementioned prior art system.

The inlet can be a simple "T-piece" in the retriculation pipe which extends through an adjacent mortar layer to the exterior of the brick cladding. A connector can be fitted to the free end of the "T-piece" for connecting to a hose for recharging purposes. A plug will normally seal the end of the "T-piece" between recharging.

Preferably, the retriculation pipe is manufactured from polyethylene or the like plastics material and has a plurality of openings through which the termite resistant solution passes into the granular material.

A polymer sheeting can be placed over the upper surface of the absorbent granular material and the retriculation pipe to protect the granular material, reduce evaporation of the termite resistant solution from the granular material and to assist in the even dispersion of the termite resistant solution throughout the absorbent granular material.

Another step in the installation method can comprise the insertion of an inspection tube in a mortar layer of the brick course above the mortar layer through which the "T-piece" extends. A bore scope can be inserted into the inspection tube when it is desired to check for termite activity in the cavity to thereby determine whether the absorbent granular material needs 8 re-treatment with the termite resistant solution, and/or to ensure that there has been no penetration of termites into the building cavity.

Advantageously, the efficient and effective means for recharging the termite resistant solution will mean cost benefits and potential self treatment by the home owner.

Another step in the installation method can comprise the insertion of an inspection tube in a mortar layer of the brick course above the upper level of the absorbent granulated material. A bore scope can be inserted into the inspection tube when it is desired to check for termite activity in the cavity to thereby determine whether the absorbent granulated material needs re-treatment with the non-toxic termite resistant solution.

In order that the invention may be more fully understood and put into practice, preferred embodiments thereof will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of a termite barrier according to the first aspect of the present invention; Figure 2 is a cross-sectional view of a termite barrier according to the second aspect of the present invention.

Figure 1 shows a monolithic slab 10 with a brick veneer cladding 11 and a timber framework 12, as is found in many conventional building constructions. A typical cavity 13 separates the brick veneer cladding 11 from the timber framework 12 by at least 30mm and a dampproof course 14 extends across the cavity over the first course of bricks The bottom of the cavity 13 is filled with crushed, sized pumice stone 16 having a mean particle size of 1mm, which has either previously been soaked in a non-toxic termite resistant solution consisting of a mixture of natural oils and natural timber saps, or is treated with such a solution after placement in the cavity. Treatment can occur before too many courses of bricks are laid by pouring or spraying the solution into the cavity, or by injection through a plurality of tubes 17 which are spaced along the first course of bricks in the mortar joints just below the upper level of the bricks. Tubes 17 are provided, in any event, for retreatment after a period of time, usually counted in years, to replace any of the non-toxic termite resistant solution which may have evaporated or broken down into less effective materials. Each tube 17 is provided with a cap 18 to prevent ingress of vermin or dirt.

Inspection ports 19, also with caps 20, are provided at spaced intervals in an upper mortar joint to enable the effectiveness of the termite barrier to be monitored over time and to access whether further treatment of the pumice stone is required with the nontoxic termite resistant solution.

In order to prevent disturbance of the pumice stone when it is being treated with the non-toxic termite resistant solution by way of the treatment tubes 17, a plurality of 316 grade stainless steel barriers 21 having a deflection face 22, are located on the top of the first course of bricks so that their deflection faces 22 extend into the pumice stone and are spaced just beyond the inner opening of each of the tubes. Such a construction means that a high pressure injection of non-toxic termite resistant solution impinges on the deflection faces 22 rather than directly into the pumice stone, thereby leaving the pumice stone substantially undisturbed.

Figure 2 shows a partial cross-section of the perimeter of a monolithic concrete slab 30 is shown supporting a house framework 31 and a brick cladding 32.

A cavity 13 between the vertical edge of the concrete slab 30 and the brick cladding 32, is filled to the height of the first row of bricks 34 with crushed, sized pumice stone 35 having a mean particle size of 1mm.

A 12mm diameter polyethylene pipe 36 is laid on top of the pumice stone 35 adjacent the vertical edge of the concrete slab 30, and extends the entire perimeter of the slab. The polyethylene pipe 36 has slits formed along its length to enable the passage of termite resistant solution therethrough during charging of the pumice stone A polymer sheeting 37 extends over the pumice stone 35 and the polyethylene pipe 36 to protect the pumice stone and to evenly distribute the termite resistant solution within the pumice stone.

A sheet of damp proof material 39 extends from the second mortar course 40 across the cavity 33 and part-way up the framework 31 in the usual manner.

Inspection tubes 41, with caps 42, are provided at spaced intervals in an upper mortar joint to enable the effectiveness of the termite barrier to be monitored over time and to assess whether further treatment of the pumice stone is required with the non-toxic termite resistant solution.

When treatment or re-treatment is required, termite resistant solution is injected into the retriculation pipe 36 through one or more suitably located points on the perimeter of the building where the retriculation pipe is connected by means of one or more "T-pieces" through the second mortar layer 40. The termite solution seeps out through the slots in the retriculation pipe 36 and is distributed by the polymer sheeting 37 over the entire surface of the pumice stone into which it absorbed. Treatment continues until saturation of the pumice stone 35 occurs; the inlet ports are then sealed and the termite barrier is fully functional.

The use of a granular material as a termite barrier means easy and quick installation, and means that the integrity of the barrier is maintained should there be any shifting or cracking in its vicinity as the granular material will move to accommodate such changes.

Whilst the above has been given by way of illustrative example of the invention, many modifications and variations may be made thereto by persons skilled in the art without departing from the broad scope and ambit of the invention as herein set forth.

Claims (16)

1. A termite barrier comprising an absorbent granular material impregnated with a non-toxic termite resistant solution.

2. A termite barrier according to claim 1 wherein the non-toxic termite resistant material is selected from the group consisting of pyrethrums, chlorpyrifos, chlorfos, mixtures of natural oils and natural timber saps.

3. A termite barrier according to either claim 1 or claim 2 wherein the absorbent granular materials are selected from the group consisting of clays and pumice stones which .have been crushed and sized to produce a mean particle diameter within the range of approximately 0.05 to 5mm; and absorbent polymers and carbons.

4. A method of installing a termite barrier in a cavity of a slab-on-ground building having a masonry veneer cladding. The method comprises the step of filling the cavity with an absorbent granular material impregnated with a non-toxic termite resistant solution, to the depth of a single course of brickwork.

A method according to claim 4 further including the step of providing at least one access port from the exterior of the building to the absorbent granular material.

6. A method according to claim 5 wherein the access port includes a tube having a cap on the outer facing end which is located just below the upper level of the first course of bricks.

7. A method according to claim 6 wherein a deflection plate is spaced from the inner end of the tube.

8. A termite barrier comprising an absorbent granular material impregnated with a non-toxic termite resistant solution, which granular material is located within the lower region of a cavity of a masonry-clad concrete slab-on-ground building, the improvement comprising a retriculation pipe also located in the lower region of the cavity, which is designed and arranged to deliver the non-toxic termite resistant solution to the absorbent granular material.

9. A termite barrier according to claim 8 wherein the retriculation pipe is laid on the surface of the absorbent granular material against the vertical wall of the concrete slab.

A termite barrier according to either claim 8 or claim 9 wherein the retriculation pipe has a single inlet for the termite resistant solution.

11. A termite barrier according to claim 10 wherein the inlet is a "T-piece" in the retriculation pipe which extends through an adjacent mortar layer to the exterior of the brick cladding.

12. A termite barrier according to any one of claims 8 to 11 wherein a polymer sheeting is placed over the upper surface of the absorbent granular material and the retriculation pipe.

13. A method for recharging an absorbent granular material located in the lower region of the cavity of a masonry clad concrete slab-on-ground building, with a termite resistant solution, which method comprises passing the termite resistant solution into a reticulation pipe located in the lower region of the cavity so that the termite resistant solution percolates out through the retriculation pipe wall into the absorbent granular material.

14. A termite barrier substantially as herein described with reference to the drawings.

A method of installing a termite barrier substantially as herein described with reference to the drawings.

16. A method of recharging an absorbent granular material substantially as herein described with reference to the drawings. DATED this 24th Day of April 2003 Terry John Trapnell and Paul Joseph Reid By their Patent Attorneys CULLEN CO