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Our Treatment Warranty

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When timber is pressure treated with TANALISED C  Oxide preservatives in accordance with relative

New Zealand specifications and used as prescribed therein, it can be expected to have a long and 

trouble-free life.


ARCH WOOD PROTECTION (NZ) LTD therefore offers the purchaser of timber, posts or poles treated with TANALISED C and carrying the approved brand or label, the following warranty:


ARCH WOOD PROTECTION (NZ) LTD will supply new TANALISED C treated timber at any time within 50 years of purchase, to replace any timber which complied with the above requirements for 

treatment, branding and end use, and which becomes unfit for further use due to fungal or insect attack.


This warranty does not cover consequential effects and does not apply to timber used in marine applications or where subject to continuous water immersion. Statutory rights assured by law are not affected by this guarantee.


It is the responsibility of the purchaser to ensure that the hazard of the proposed application is correctly evaluated and that timber with the correct preservative retention level is used.

All surfaces exposed by cutting to length, notching, rebating, drilling or similar operations must be thoroughly resealed with application of a Arxada supplied or approved heavy duty remedial wood preservative such as CN Timber Protective Emulsion or CN Timber Oil. Failure to adequately reseal wood surfaces exposed from these operations will void this Warranty.”


Use of treated wood for cattle yards and other intensive use animal management enclosures.


CCA treated wood is a useful material for posts and rails for the construction of typical rural 

infrastructure such as cattle/sheep/goat yards and other animal management structures.   

However, premature failure of treated wood posts at the ground contact sections in these 

installations has been noted in a number of cases, particularly with intensive and frequent animal contact.


The likely reason for premature failure is aggressive decay organisms in highly nutrient enriched ground media due to animal faeces and urine.  Increased levels of organic nutrients such as nitrogen (ammonia and urea) and phosphorous (such as phosphates) can lead to increased rates of premature decay of treated wood. In addition, high levels of these nutrients may also have a direct effect on 

depletion of the preservatives from wood by ion exchange or possibly chemical chelation mechanisms.


In normal soil conditions with low to moderate levels of biological activity and nutrient loads, CCA treated wood is very reliable and is expected to last for decades. In the cases where treated wood posts are used around intensive and frequent animal containment areas, the following steps are recommended to reduce the likelihood of premature decay:  


Use H5 level treated posts and poles where these conditions are expected. H5 treatment level has

approximately 50% higher concentration of preservative compared to H4 and is recommended for more severe conditions, or where very long service life is expected.


When adding concrete to post or pole foundations extend concrete around the post above the surrounding ground level and sloping concrete away from the post to facilitate runoff of urine and faeces.


Dip posts in or paint posts with a heavy bitumen or waterproofing coating (such as Bitpost from Biosymph) in the ground contact surface and up to at least 30 cm above ground level.  This will reduce the penetration of water and nutrients into the posts which is what causes premature decay.


Alternatively, wrap the same lower ground contact area of posts with a robust DPC (damp proof course) such as butyl rubber or fibre reinforced bituminous wrap (such as Ardex WPM 117). Ensure that the wrap extends at least 30 cm above the ground level.


Ensure that animal enclosure areas are free draining and that animal wastes do not collect around posts and poles.


With these simple measures, posts used in these situations are expected to provide long and trouble free service.

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