AU758095B2 - Method of termite proofing a cavity walled structure - Google Patents

Description

I I.

"1 1iuWUii 21V5191 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: 5** Invention Title: METHOD OF TERMITE PROOFING A CAVITY WALLED STRUCTURE The following statement is a full description of this invention, including the best method of performing it known to us IP Australia Documents received on: 2 5 MAR 1999 Batch No:I

CD

-"1 METHOD OF TERMITE PROOFING A CAVITY WALLED STRUCTURE Field of the Invention This invention relates to the termite proofing of a cavity walled structure.

Backaround to the Invention Termites are voracious consumers of cellulosic materials such as wood which form an important part of many buildings, being commonly used in frames and internal partitions, walls and fixtures. The risks to buildings caused by termite insects are well identified and various proposals are available to minimise the risk of attack. For example, chemical and physical barrier treatments are known for this purpose. Chemical means have encompassed spraying techniques and many physical barrier methods are also available.

Selection of the termite proofing method depends on considerations of cost, health, ease of re-treatment (where appropriate) and efficacy.

The Applicant has previously developed pipe treatment and retreatment systems for the protection of structures from attack by termites. In such pipe treatment systems, termiticide is charged to the pipes of the system and enters surrounding ground through apertures of suitable size and spacing in the pipes of the system. Such pipe systems form the subject of Australian Patent Nos.

583405 and 630228; and Australian Patent Application Nos. 34198/97 and 48531/97, the contents of which are herein incorporated by reference. The pipe S- systems are particularly suitable for preventing attack of termites directly from outside the building, through construction joints in a slab; gaps between slab penetrations such as pipes for water and sewerage; and the slab. The pipe treatment systems are applicable to various kinds of slab design such as monolithic slabs, infill/footing slabs, waffle pod slabs and others.

Pipe treatment systems such as these are constructed and operated in accordance with Australian Standard AS 3660.1-1996 (Reticulation Systems for Termiticide Application), the contents of which are hereby incorporated by reference, and are efficacious to slab protection while allowing non-destructive retreatment of structures as the potency of termiticide degrades over substantial periods of time. Excess chemical usage and evenness of distribution thereof to surrounding ground may also be largely avoided by use of such pipe treatment systems.

The Applicant has noted that external cavity walled structures present a particular problem from the point of view of termite attack as cavities, especially cavities which are in darkness, offer a convenient route for termites to enter the structure and cause damage.

SUMMARY OF THE INVENTION It is the object of the present invention to provide a system of termite proofing a structure that addresses potential entry by termites to the structure through cavities, especially peripheral structural cavities, of the structure.

With this object in view, the present invention provides a system for termite proofing a structure having a peripheral external cavity wall extending about the 1periphery of said structure in which the cavity of the external cavity wall is defined by an external wall component, a base structural member and an internal wall 15 component, said system including: a pipe termiticide distribution means charged with termiticide extending through said cavity of said peripheral external cavity wall and about said structure, said pipe termiticide distribution means having apertures along its length to disperse termiticide; and a layer of a I particulate building material located in a base of said cavity wherein said pipe termiticide distribution means is adapted to disperse a volume of termiticide calculated with reference to volume and/or porosity of said layer into said layer of particulate building material to form a peripheral termite barrier extending about "said periphery of said structure.

The pipe termiticide distribution means may take the form of a reticulation system. It may take the form of tube(s), pipe(s) or a system of these, any desired number and layout of which, may be located within the cavity. The distribution means may, and advantageously is, pressurized for dispersing termiticide to saturate the layer of particulate building material. Such tubes or pipes are made from a termiticidally inert material.

The pipe termiticide distribution means may be supplemented by an absorbent or adsorbent material which retains termiticide at appropriate concentrations for termite destruction. Use of such adsorbent materials forms the subject of the Applicant's co-pending Australian Patent Application No. 48531/97, the contents of which are hereby incorporated by reference. A particularly preferred absorbent or adsorbent material is a geotextile which may be placed proximate pipes of a pipe distribution means for the purpose described above.

The geotextile may be wrapped, sleeved or adhered around the pipe. A sufficient quantity is used to generate the desired termite-proofing effect.

The layer of building material may be conducive to distribution of the termiticide remote from the termiticide distribution means within the cavity. The distribution may be uniform. The layer of material may at least partially surround the termiticide distribution means and could wholly surround or cover it.

Conveniently, the particulate building fill material, is sand of known porosity and/or sieve range.

The cavity, while partly or wholly defined by plural walls making up an extrernal cavity wall, may also be partly defined by the slab, footing or other base structural member upon which a component wall of the peripheral cavity wall, of 15 the structure is built. An upper portion of the slab footing may form the base of :the cavity. The component walls may be of any suitable construction material, for example of one or more of, or mixtures of, brick, brick veneer, masonry and concrete.

In addition, the system may include water or damp proofing of the cavity containing the termite distribution means for example, by using a cavity flashing or other water or damp proofing means to prevent substantial access of water or moisture to the bed of building material in which the termite distribution means is located. By substantial access is meant a degree of water or moisture ingress that may damage the building and/or reduce the efficacy of termite proofing.

The system may replace other techniques of termite proofing, for example direct treatment of surrounding soil, but may be supplemented by the use of additional termite proofing installations and methodology, for example as described in the Australian Patent Nos. 583405 and 630228; and Australian Patent Application Nos 34198/97 and 48531/97. Other termite proofing systems and methodology may also be employed in combination with the invention.

A still further aspect of the invention provides a method of operating the termite proofing system in accordance with any of the above described aspects of the system of the invention. Structures including such systems form a yet further aspect of the present invention as do methods of construction of such structures.

The system, method and structure and methods for constructing the structure of the invention may provide various advantages. A continuous termite barrier around the periphery of the building may be created. The barrier may use less termiticide than required by previous building protection methods. The barrier, when located in a waterproofed cavity, is not usually subject to run-off or leaching. The barrier may provide protection to construction joints between the footing and the slab; and the external wall and the footing.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be more fully understood from the following description of a preferred embodiment thereof made with reference to the accompanying drawings in which: Figure 1 is a side sectional view of a cavity wall termite proofed in 15 accordance with the method and structure of the present invention; o.o Figure 2 is a plan view of a cavity wall and slab showing the location of the termiticide distribution means; and Figure 3 is a side sectional view showing the filling point of the termiticide S* distribution means.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE

INVENTION

Referring now to Figures 1 to 3, the components of the termite proofing S. :method and system, a structure including it and a method of constructing the structure in accordance with the present invention may be determined for the protection of a peripheral cavity brick wall 15 of a structure, say a house. The system 10 comprises the termiticide reticulation system 20 which may be in the form of a reticulation pipe system comprised of pipes 21 and 22 and termiticide supply pipes and fittings as will be described. The pipes 21 and 22 are made of a termiticidally inert material. A plastic such as PVC is appropriate. Materials such as polypropylene, other polymer, copper and so on may also be used.

UPVC moulds may be used. In the embodiment shown, only a single pipe is shown located in each branch 50a and 50b of the cavity 50 but plural pipes may be employed in each branch 50a and 50b in accordance with the invention.

The pipes 21 and 22 are provided with apertures 23 of suitable number, size and spacing to allow termiticide to exit the pipes 21 and 22 and disperse away from the pipes 21 and 22 to afford protection against termites, subject to the termiticide having sufficient potency to achieve this result. A liquid formulation is preferred. Description of a preferred termiticide follows below which will achieve the desired protection.

The pipes 21 and 22 are advantageously sleeved in Permecover geotextile membrane 25, a portion only of which is shown for ease of illustration, which improves the distribution of termiticide by presenting continuous resistance to the flow of termiticidal liquid compositions during charging of the system 10 through central filling point assembly 30. The geo-textile membrane 25 also has substantial adsorption capacity, retaining sufficient quantities of the termiticide that it forms part of the termiticide barrier.

The pipes 21 and 22 are advantageously placed on a layer 40 of building fill material, for example sand such as clean packing sand, with sieve sizes as specified in AS-1152-1993, which has been lightly compacted. Following installation of the pipes 21 and 22, a further sand layer 41 is placed above the pipes 21 and 22. The sand layer 41 is also advantageously compacted.

The pipes 21 and 22 are typically installed radiating out from the central filling point assembly 30 with which they communicate through supply pipe risers 27 which are undrilled. Suitable faucets, plugs and/or valves, plugs 28 are shown for illustration, may be arranged in the risers 27 to facilitate charging and recharging. The central filling point assembly 30 should be located out of reach of children and wall mounting in child-proofed wall box 33 is a convenient means by which to achieve this.

The system 10 is conveniently installed early in the construction of the brickwork. For instance, when the outer course 16 of bricks is a few, say two or so bricks high, there is access for installation of the system 10. The bricks forming the inner component wall 19 of wall 15 are built on slab 90. The slab is of footing slab construction placed on footing 95 though other forms of slab could be used. The slab 90 should be constructed in accordance with Australian Standards.

The first sand layer 40 is placed in the cavity 50 upward from the footing 95 to a point below the lowest point 19a of inner component wall 19, following cleaning of the cavity 50 to remove any debris. This portion of the cavity 50 is defined by outer component wall 16, slab 90 and footing 95. The sand layer 0. may be of any desired depth, subject for example to cost considerations and lightly compacted. For the purposes of example, the compacted sand depth may be between 100mm and 150mm, say 130 mm. Reference works on the physical properties of soils and sands specify wide ranges in the porosity (or void ratio) of naturally occurring materials. However, it is expected that the range will be somewhat narrower for cleaned, washed sands since the more variable material has been removed. The porosity range reported for clean, washed sands is 29% to 50%, depending on the nature of the sand and degree of compaction. Since the sands specified herein are to be cleaned to a specified sieve range and compacted in a reasonably accessible location, the porosity of the final bed is expected to be at the low end of the range of porosity and may, for the purposes of illustration, be assumed to have a porosity of 29%.

Thus the 60 lineal metres of cavity containing 0.4 cubic metres of sand will have about 0.116 cubic metres or 116 litres of void space when completely dry.

Some of this void space may contain moisture since the sand is most unlikely to be completely dry and, in moist condition, is much easier to handle and compact. By moist sand is meant a sand containing about 4% moisture, a degree of moisture that constitutes a relatively small portion of the void space and taken into account only to ensure that the slight surplus of liquid to ensure saturation of the sand is achieved.

The piping system 20 is installed on top of the compacted sand layer The pipes 21 and 22 making up the system may, and should, be positioned such that the apertures 23 face upward. The pipes 21 and 22 may be wrapped or sleeved in the geotextile membrane 25 prior to placement. They may be laid horizontally, substantially horizontally, or at any desired angle to the horizontal.

Pipes 21 and 22 may have vertically disposed portion(s) along their length.

They may be positioned at any desired point within cavity 50 subject to the consideration that the arrangement be effective for preventing access of termites to the structure. Generally, therefore, the pipes 21 and 22 will be located at or *."about ground level 100.

A further layer 41 of sand is applied to cover the pipes 21 and 22 and compacted to desired depth. The depth of this layer 41 may be less than that of the first, having a compacted depth between 20 and 60 mm, say 40 mm compacted depth. The uppermost portion of sand layer 41 may extend between both component walls 16 and 19 of cavity brick wall 15. The described arrangement of layers 40 and 41 is effective and advantageous but other arrangements may be employed which are constrained only by the desired arrangement and placement of pipes 21 and 22.

Openings in the brickwork below the dampcoursing are sealed by mortaring.

So The bore of the pipes 21 and 22 is selected having regard to the amount of termiticide to be distributed and the void or cavity space. The bore may be varied within a large range but indicative of suitable bore for a typical void space using a single pipe system would be 20 mm nominal bore. The number and spacing A of the apertures 23 within the pipes 21 and 22 may also be widely varied but indicative of a suitable arrangement would be two apertures 23 drilled or formed into the pipes 21 and 22 every 200 mm of pipes 21 and 22. In any event, the spacing A is selected having regard to the desired termiteproofing effect and the hydraulics of the system On completion of the above installation, a damp proofing flashing 80 may be positioned and secured to seal the cavity 50. Any excess of packing sand

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8 should be removed. The flashing 80 is formed with an aperture 81 to allow supply pipe risers 27 to run through and a portion 80a of the flashing 80 is overlapped over the riser 27 and appropriately sealed for example by securing the portion 80a to the pipe by an electrical cable tie or otherwise.

The range of cavity spaces protected is as broad as the range that is commonly employed in the building industry. For a nominal brick cavity width of mm and a typical perimeter wall length, say 60 lineal metres of cavity typical of a medium to large house would contain about 0.4 cubic metres of fill installed as above but this is provided for the purposes of illustration only as the exact quantities and building dimensions are at the option of the builder. The S- invention is applicable without reference to particular quantities and dimensions.

All termiticide products may be employed within the pipes 21 and 22 of S• the system 10 though should be used within the manufacturer's instructions with liquid formulations such as emulsions being of special advantage and importance. A most preferred termiticide is Biflex®, because of its particular characteristics of biological performance, as well as homeowner, applicator and environmental safety. Biflex® termicide is an emulsifiable concentrate containing bifenthrin and should be used in accordance with the manufacturer's o*oo instructions.

For a vertical barrier, such as is shown, the recommended soil S: concentration should concur with that shown on the product's label. Biflex® is a registered trade mark of FMC Corporation.

The preferred method of application of the termiticide emulsion is to pump sufficient volume of the material into the termiticide reticulation system through the central filling point 30 to just saturate the packing sand around the pipes 21 and 22. A suitable pump may be a Davey Fire Pump. To account for variations in discharge through the apertures 23 throughout the pipes 21 and 22, and to allow for purging of liquid remaining in the pipes 21 and 22, a slight excess volume of liquid is preferable. Any surplus liquid will pool on the surface of the packing sand until absorbed. The surplus ensures that all parts of the fill are at or near saturation, and thus that the barrier is substantially continuous 9 affording protection throughout the width and depth of the barrier.

For a volume of 0.4 cubic metres in the cavity 50, a minimum of 200 ml of Biflex® concentrate should be used. This concentration is much higher than required for horizontal barriers which require a distribution of about 25 ml Biflex® concentrate per square metre. For an average depth of 200 mm, this is the equivalent of 125 ml/cubic metre or about one quarter of that of the vertical barrier.

Since the void space in the sand requires about 116 litres of liquid to saturate, the emulsion can be diluted by as much as the ratio of 200 ml into 116 litres. This is a dilution ratio of about 600:1, more precisely 580:1 or 0.17%. This is a high ratio assuming that the delivery and distribution is perfectly evenly distributed. A perfectly even distribution is most unlikely to be achieved in practice and so the actual ratio might fall somewhere in the range of 200:1 to 600:1. A practical working dilution would be about 300:1 or 0.3% to ensure at least the minimum concentration throughout the sand.

A relatively small amount of termiticide is required, typically a concentration of about 1% may be used which will meet the criteria for residual soil concentration. The concentration must be sufficient to confer effective a. a.

S"termite-proofing.

The diluted termiticide is pumped or otherwise injected or delivered into the termiticide reticulation system 20 through central filling point 30 so arranged to achieve a substantially even distribution throughout the cavity 50 fill. As the cavity 50 volume is relatively small, yet presents a major potential access point for termites, it is very desirable that substantially all of the termiticide solution reaches the sand fill so that an effective barrier will be created.

The volume of piping in the reticulation system 20 forms a relatively high proportion of the volume in the termiticide reticulation system 20. The volume of liquid contained in 60 lineal metres of piping is approximately 19 litres, or approximately 17% of the total volume of liquid to be delivered. The volume of liquid in the piping should be delivered to the sand fill, or accounted for as lost solution. A preferred method is to purge the liquid from the pipes 21 and 22 if practical, since leaving it in the pipes 21 and 22 may lead to crystallisation inside the pipes 21 and 22 between recharges and this is undesirable.

Any liquid left in the pipes 21 and 22 at charging may be purged with compressed air or another suitable compressed gas conveniently introduced at filling point 30. This should remove liquid remaining in the pipes 21 and 22 without danger of washing termiticide out as may be the case with a liquid purge, say with water, which is solvent of termiticide. By way of example, purging with 50 psi compressed air after charging should eject substantially all of the liquid in the pipes 21 and 22 into the sand fill. Compressed gas purging may be employed in any form of the method, system or structure in accordance with the present invention.

Modifications and variations may be made by the skilled reader on consideration of the disclosure and such modifications and variations form part of the present invention.

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Claims (17)

1. A system for termite proofing a structure having a peripheral external cavity wall extending about the periphery of said structure in which the cavity of said external cavity wall is defined by an external wall component, a base structural member and an internal wall component, said system including: a pipe termiticide distribution means charged with termiticide extending through said cavity of said peripheral external cavity wall and about said structure, said pipe termiticide distribution means having apertures along its length to disperse termiticide; and a layer of a particulate building material located in a base of said cavity; wherein said pipe termiticide distribution means is adapted to disperse a volume of termiticide calculated with reference to volume and/or porosity of said layer into said layer of particulate building material to form a peripheral termite barrier extending about said periphery of said structure.

2. The system of claim 1, wherein a termiticide adsorbent material is wrapped, sleeved or adhered to said pipe termiticide distribution means.

3. The system of claim 1 or 2, wherein said pipe termiticide distribution means is pressurised for dispersing termiticide to saturate said layer of particulate building material.

4. The system of any one of the preceding claims, wherein said layer of particulate building material at least partially surrounds said pipe termiticide distribution means.

The system of claim 4, wherein said layer of particulate building material wholly surrounds said pipe termiticide distribution means. 12

6. The system of any one of the preceding claims, wherein said layer of particulate building material contains particles in a specified sieve range.

7. The system of any one of the preceding claims, wherein said particulate building material is of selected porosity.

8. The system of claim 7, wherein said particulate building material is sand having porosity between 29% and

9. The system of any one of the preceding claims, wherein said particulate building material is installed in moist condition in said cavity.

The system of claim 9, wherein said calculated volume of termiticide is calculated with reference to a moisture content of said particulate building material.

11. The system of any one of the preceding claims, wherein said peripheral termite barrier has a determined minimum concentration of termiticide. o•

12. The system of any one of the preceding claims, wherein said layer of particulate building material having predetermined depth is compacted.

13. The system of any one of the preceding claims, wherein said layer of particulate building material is lightly compacted.

14. The system of claim 12, wherein said adsorbent material is a geotextile.

A method of operating the termite proofing system of any one of the preceding claims.

16. A structure incorporating the termite proofing system of any one of claims 1 to 14. 13

17. A method of constructing the structure of claim 16. DATED this 2 8 th day of October 2002. TERMGUARD PTY LIMITED WATERMARK PATENT TRADEMARK ATTORNEYS 2 1 st FLOOR, "ALLENDALE SQUARE TOWER" 77 ST GEORGE'S TERRACE PERTH WA 6000 o *o* o.e. eo o *g* *o