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Durability Statement:
The purpose of this statement is to provide information to Building Regulators,
Designers and Homeowners regarding the expected durability performance of Wespine
Blue treated timber products. This durability performance statement has been prepared in response to publication of the "Guideline on Durability in Buildings" by the Australian Building Codes Board.
Product Description
Wespine Blue is a new affordable, in-line or rapid batch treatment system that
provides effective protection to pine framing timber against termites (excluding Mastotermes darwiniensis)
and European House Borers under conditions which are described as H2 - F according to AS1604 (dry, above ground, protected from weather and moisture).
The treatment employs a unique blend of oils that facilitate surface penetration with the well proven timber protection insecticide permethrin (and other insecticides potentially). Synthetic pyrethroid insecticides such as permethrin are highly repellent and contact is toxic to termites and European House Borers.
The Wespine Blue system places the treatment barrier around the outside of the wood where it is most needed.
By ensuring an adequate envelope, rather than a superficial treatment, the insecticidal protection will be
retained over the long term.
Intended Application
Seasoned softwood is an ideal timber for a wide range of building applications, including
all roof, wall and floor framing. Specifically these are situations where the timber
is protected from direct weather and moisture but may be subject to termite or borer attack.
Wespine Blue treated softwood is intended to provide a deemed-to-satisfy termite or borer
resistant construction by rendering the structural timber termite resistant in accordance
with AS3660.1 for areas not subject to Mastotermes darwiniensis (south of the Tropic of Capricorn).
Although termite and borer resistant construction using preservative treated or naturally termite/borer resistant
timbers for all structural elements below the termite barrier is deemed to- satisfy, termites and borers are not prevented
from entering the house envelope. Koppers Arch recommends good building practice such as whole-of-house
protection to mitigate the unwelcome access by termites or borers. Whole-of-house protection can take
the form of physical or chemical barriers, together with regular inspections and maintenance. The use
of H2 treated structural framing together with whole-of-house protection provides a comprehensive
solution to the termite or European House Borer hazard, and peace of mind for the building owner.
Specific Service Conditions
Service conditions for Wespine Blue treated softwood framing are internal,
above ground, dry, and potentially subject to attack by termites or borers south of the Tropic of Capricorn
in Australia. In addition to these standard service conditions, building timber may be subject to temporary
weathering for a maximum period of up to 3 months while material is in storage and the frame is in
construction. These service conditions correspond to a Hazard Class 2 - F environment as defined in AS1604.1.
Material Characteristics
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Timber species: |
Pinus ellioti (slash pine) Pinus caribaea (Caribbean pine) Pinus radiata (radiata pine) Araucaria cunninghamii (hoop pine) |
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Penetration zone: |
Pinus radiata and Araucaria cunninghamii - Outer 5mm from all faces |
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Timber sizes: |
All timber sizes up to 300mm finished width and 45mm finished thickness. |
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Retention (analytical zone): |
Minimum of 0.02% mass/mass permethrin in the outer 0 to 5mm zone. |
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Termite species: |
Coptotermes spp, Schedorhinotermes spp, Nasutitermes spp, Heterotermes s |
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Region of use: |
South of Tropic of Capricorn |
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Proposed Brand Designation: |
H2 - F |
The registered label calls for a permethrin loading of a minimum 0.02% m/m in the outer 5mm. For Pinus radiata 5mm penetration all round regardless of heartwood or sapwood. For Pinus elliottii and Pinus caribaea heartwood penetration is not required (as per AS1604.1). Analysis of pine treated with Wespine Blue has shown a well defined envelope to a depth typically of 5mm in softwood (Kennedy and Cobham 2003). Koppers Arch has received APVMA (previously NRA) approval for Wespine Blue as a
timber preservative for protection of pine framing timber from termite and borer
species south of the Tropic of Capricorn (areas not subject to Mastotermes darwiniensis).
Note: Wespine Blue treated timber would be deemed not to be termite resistant north of the Tropic of Capricorn.
Testing of Wespine Blue treated pine with CSIRO (Creffield and Owen 2002) and DPI (Peters and Fitzgerald 2002)
has shown that the 5mm envelope of permethrin at 0.02% m/m provides excellent protection to framing size timber
against Coptotermes and Schedorhinotermes (all species apart from Mastotermes darwiniensis). The DPI trial included Wespine Blue treated sample boards that had been cut after treatment to expose the untreated core and no additional end sealant was applied. These samples were not attacked by either Coptotermes or Schedorhinotermes.
Design and Detailing
Good design and detailing practice should ensure that the building is protected from moisture and not exposed to unnecessary decay hazard. Guidelines for good building practice are given in TRADAC Technical Data Sheet 10 "Recommendations for the use of seasoned softwood framing".
Fasteners
Standard steel nails will be adequate for all fixings in terms of durability.
Ventilation and Ground Clearance
Roof, sub-floor and external wall cavities should be ventilated. Minimum ventilation and clearance requirements for sub-floors should be provided in accordance with the Building Code of Australia (BCA).
Onsite Handling and Weather Exposure
Wespine Blue treatment will not be significantly impaired by normal exposure and handling prior to and during construction. Do not store Wespine Blue treated timber in ground contact.
Workmanship
Quality of workmanship in all building construction is necessary to ensure the satisfactory performance of the construction for the long term.
Maintenance
Regular building inspections for termite or borer activity and maintenance of the inspection barrier are required under
AS3660.1. Maintenance and inspection to ensure that water leaks or failure of weather tightness do not expose the Wespine
Blue treated timber, untreated timber, and other construction materials to degradation from
excess moisture or decay hazard.
Assessment of Durability
The durability of Wespine Blue treated timber has been assessed on the basis of
published references, together with established historical and performance data.
A number of studies have shown that in dry weather protected building applications,
synthetic pyrethroids insecticides have a long residual life in timber
(Orsler and Stone IRGIWP32881984, Berry and Read IRG IWP/1569-92, Powell and Robinson
J. of Economic Entomology October 1992). These references indicate a projected
ultimate service life in timber of up to 50 years depending on the conditions. With
the non-volatile drying oils in Wespine Blue and in combination with good building
practice and maintenance, protection against termites will be afforded. In addition
the exposure to weathering during the construction phase needs to be considered. Framing timber can typically be exposed to sunlight and rain for up to twelve weeks during construction. Analysis of retained Wespine Blue treated timber samples after more than 6 months of exterior weathering have shown that the active constituent in the envelope zone remains at effective concentrations. Finally, Koppers Arch have supplied permethrin based timber treatments in commercial quantities since 1995 for H2 - F uses (framing and trusses). In 8 years there has not been a single case of failure reported to Koppers Arch of permethrin based treatment in H2 - F application.
