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About Tenco
Tenco is one of New Zealand’s largest exporters of forest products. We have built to this position since 1991 when the company was set up to export lumber to growing Asian export markets.  Experience and reputation count; from small beginnings Tenco has become the largest independent exporter of New Zealand lumber and New Zealand’s 4th largest log exporter.  Tenco has a regular shipping program of their own log vessels and in combination with these and other ships currently calls  at 7 New Zealand ports (5 North Island and 2 South Island).
Tenco buys standing forests. Tenco regularly buys smaller tracts of forest to harvest immediately or immature forests to hold until harvest time. A deal with Tenco is a certain transaction. The owner and Tenco will agree on a value of the tree crop and then Tenco will pay this amount to the owner either in a lump sum amount or on rate per volume unit out-turn from the forest depending on the nature of the tree crop.

Tenco is actively interested in buying harvestable forests or trees from areas including all the North Island (except the Gisborne and East Coast districts) and Nelson & Marlborough in the South Island .
If you own a forest in this area (16 years and older) and are ready to enter into this kind of agreement Tenco is interested to develop something with you.
Please contact: 
Work: +64 7 357 5356  Mobile:  +64 21 921 595

Member Blogs

Recent blogs:

Eucalypt Pudding

Shem Kerr's blog
Monday, May 06, 2019

You have many contacts among the lumberjacks
To get you facts when someone attacks your imagination…
But something is happening here and you don't know what it is
Do you, Mr Jones?"
   Ballad of a Thin Man; - Bob Dylan

The trouble with specialty timbers is they're like Ostrich feathers the niche market can disappear before your eggs have hatched.

Back in the wood old days when I was alive we had a whole lot of products made of what would now be called specialty timbers:

Road-men with picks, shovels and wooden wheel barrows excavated the carriage-way. There were wooden  road paving blocks. Scows sailed up on the beach at high tide for the wooden trucks to come down at low tide and take the shingle cargo.

“Butter-box” buses were built from kahikatea, the same timber used for curd vats and factory butter-churns. Wooden phones as big as your head, were fixed to the wall, connected by wire slung on eucalypt poles to a wooden switchboard. Eventually the poles rotted off and the worms under-grounded the network. No NIR sensor, nor any other such tools that a farm forester takes for granted today.

I first came across the farm foresters while I was studying at Salignadale. They were very old men dressed in period costume driving vintage trucks heavily laden down by a single log hanging off the back. Around that time it began to be seen that there was a need to grow more trees, and fast.

A body of evidence was built up by the NZFFA & the Forest Service (later FRI) on the performance of the durability class 3 (D3) eucalypts: E botryoides and E saligna and their hybrids; as well as the D2 & D3 eucalypts E pilularis and the stringybarks. These were trialled. They were grown well on forestry sites, easily milled and built with  The pudding has been eaten: that's the proof. There continue to be growers with healthy E saligna crosses having minimal end splitting.

Cut to now, with proposed anthropogenic global warming; a perceived need for lots of trees growing fast; greater competition for higher classes of soils; disruptive technology, and social change. Are the plantation owners really backing a programme fit for a future of higher risk and tighter constraints?

What else is changing for specialty woods before your next crop is harvested? Environmentally benign in-ground timber treatments derived from forestry by-product; precisely-controlled post-avoiding horticultural robots; electronic fencing; tiny houses; eating out.

What about carbon neutral concrete; wireless electricity distribution; mushrooms or kombucha construction composites; nimble global competitors?

Perhaps add in the advertised effects of global warming. In addition to recognised harder droughts and significant warming, there's, greater climatic variability; stronger storms; salt winds driven further inland; more severe rain events; humidity extremes; higher erosion, wind-throw, etc.

Take in a groundswell of public and consumer distaste for environmental degradation; 

along with a greater competition for higher classes of soils by horticulture, lifestyle blocks; and urban sprawl may mean that available land close to a port is insufficient for the industry.

Keeping these points in mind, we may note that the plantation owners have allocated the bulk (60%) of eucalypt research funding to three ground durable species of relatively low productivity; nothing to the faster growing and sometimes better D3 species; and then 40% to the non-durable ones.

In the narrow scope of profitability: the research into non-durable species will be useful for areas that continue to be cold enough. But the ash group of eucalypts are becoming uncomfortable with the heat in the northern portion of this pot. Ground durable species from relatively non-variable climates should also be considered with a lot more caution.  There's been very good growth of some D1 eucalypt shelterbelts, but on horticultural soils only.

The most fit eucalypts to be the plantation owners’ “ideal forest tree” and also to meet the strategic objectives of their Science and Innovation Plan are some of the D2 to D3 stringybarks. The most applicable research is in the NZFFA/FRI (now SCION) stringybark programmes the backing for which has been left to a small number of unfashionable farm foresters. Jst as it was at Salignadale.

This may be the closest you've gotten to a market risk analysis. Mr Jones. 

[ further indepenent farm forestry blog posts can be found at  ] ð

Building System Legislative Reform Programme, public consultation

Dean Satchell's blog
Tuesday, April 23, 2019

The Ministry of Business Innovation & Employment (MBIE) administer the building code and are proposing major changes to NZ's building laws to:

  1. increase the quality of information about building products;
  2. hold people accountable for building products and their use; and
  3. reduce the risk of defects in building work.

They are also proposing to strengthen the framework for product certification.

So how might this affect growers and producers of specialty timbers? Well, I have concerns around product assurance and in particular product certification for building products.

CodeMark certified products are deemed to comply with the Building Code. Importantly, CodeMark is an unchallengeable form of product assurance that has legal status equivalent to an Acceptable Solution.

To put this into context, under the building code, before a new product can be used in buildings, evidence is required proving that durability exceeds a minimum performance threshold (as years in service).

Evaluating products for CodeMark certification is undertaken by the Certification Body, who produce an Evaluation Report that is supposed to consider code compliance. However, although this report forms the basis for the decision to award a CodeMark certificate, the basis for approval is not provided within the certificate itself. Indeed, the Evaluation Report is kept by the certifier and not made available for review, so product assurance is deemed to be provided only by the Certificate of Conformance.

So is this adequate? Is the certificate alone a satisfactory means of assurance for code compliance of the product in question? Definitely not, in my view this amounts to certifier self regulation because certifiers aren't accountable for their decisions made behind closed doors. The certificate just says the product has the tick of approval, but provides no basis for that.

Certification bodies compete in the market for business, and applicants want the competitive edge. Keep in mind that the whole purpose of the CodeMark Scheme is to provide confidence to building consent authorities and assurance to the market that certified products conform to the requirements of the building code. In light of accreditation being recently revoked for one of the product certification bodies (BCS), and given that MBIE has started a review of all BCS-issued certificates (and have even acknowledged that certification needs strengthening), one might ask whether the system is open for gaming and whether the consumer has been adequately protected to date by the CodeMark scheme. Our building code is performance-based, after all, so a lot is at stake.

So is the credibility of CodeMark certification really in question? Lets have a look at some examples of certified cladding, in particular CodeMarks that have been issued to Abodo and Hermpac for their certified exterior cladding timber products and systems.


Under NZS 3602 (the Acceptable Solution for durability), weatherboards made from cypress, redwood and cedar can all be stained, oiled or left natural. Larch, because it is less durable, requires paint protection to meet the minimum 15 year durability performance requirement. Those are the rules.

Therefore, under New Zealand's performance-based building code, to certify a larch cladding product without paint protection (i.e. just an oil coat), proof (i.e. strong evidence) would be required that the product exceeds the minimum durability requirement of 15 years service. Although such evidence may not be easy to produce for a new product or species, those are the rules and adherence to them would form the basis for any valid decision on compliance.


Hermpac, a timber importer, have included Uncoated or Oil coated Siberian larch Larix siberica as their product "DuraLarch" in two out of three of their CodeMark certified cladding systems.

So what is the durability of this new product, given that it is outside the scope of the Acceptable Solution, NZS 3602? Unfortunately I can't answer that because the basis for the decision is not available to me. I cannot review the evidence, all I have for assurance are the certificates of conformance.

Hermpac hold three CodeMark certificates of conformity for weatherboard products, all issued 31/3/2017:

In all three certificates the Australian-based certifier Global-Mark states that to meet the requirements of Clause B2 of the building code they have "relied on the independent expert and/or laboratory advise or reports" in evaluating the product. That reads a bit like smoke and mirrors, but appears to me to be stating that expert opinion can be relied on as proof of durability for the product. In reality Clause B2 spells out that the evidence required is History of use, Similar materials tests and/or Laboratory tests. Expert opinions can only support the evidence.

Now, if a product does not comply with the Acceptable Solution (in this case NZS 3602:2003), under the CodeMark scheme rules the Certification Body shall "ensure that the evaluation methodology and evaluation plan includes an Alternative Solution that has been prepared in compliance with the requirements of the NZ Building Code and which clearly demonstrates how such requirements have been satisfied" (See 2.2 Evaluation methodology). But how can I be assured that this has taken place if I can't review that Alternative Solution? All three of Hermpac's CodeMark conformity certificates list "DuraLarch" (Siberian larch, Larix siberica) but even though it was mandatory that an Alternative Solution be prepared, all I can do is trust that this was prepared. Allowing product certificates to have such content deficiency is clearly inadequate, given that product certification must be accepted by every Building Consent Authority as complying with the Building Code.

Digging a bit deeper, actually the Building (Product Certification) Regulations 2008 requires "a reference to the existence of any information that forms part of the certificate or the basis for certification". But in the Hermpac certificates there doesn't appear to be any reference to the existence of an Alternative Solution. So do their certificates even comply with the regulations?

There are also key differences between the three certificates that suggest things are awry.

In Hermpac's Bevelback Weatherboard Cavity System the certificate states that:

"Cedar weatherboards are finished with two coats of premium penetrating oil stain to Herman Pacific Limited specifications while Dura-Larch and Ashin-Dura weatherboards are treated to H3.1 and require a primer coat and two coats of exterior grade acrylic latex paint"

This contrasts with Hermpac's Rusticated, Splaycut and Multi-Splay Weatherboard Cavity System and VertiLine Vertical Shiplap Weatherboard Cavity System certificates, which only state that:

"Cedar and Dura-Larch weatherboards are supplied either raw, with one coat of machine applied premium penetrating exterior grade oil stain to Hermpac specifications"

So what is so different about the Dura-Larch in these products such that Siberian larch timber requires both treatment and paint protection in the bevelback product? Or is this just careless certification, that regardless of contradictions and inconsistencies, has become enshrined as unchallengeable?

Such inconsistencies don't end there. Only the Bevelback Weatherboard CodeMark certificate defines what Dura-Larch is (Siberian larch heartwood), so the other two CodeMark certificates name proprietary timber products without even stating what species they are. In my mind this introduces anti-competitive practices into the CodeMark scheme, setting a precedent that I am not comfortable with. Timber species can't themselves be proprietary branded products.

There are also other issues with the Hermpac CodeMarks. The other species allowed for their three CodeMark weatherboard systems is Western Hemlock, a product Hermpac call "Ashin-Dura". All three CodeMark certificates state that Ashin-Dura must be treated to H3.1. But the timber treatment standard NZS 3640:2003 does not allow Western Hemlock to be treated to H3.1, so it can't be called H3.1. Of course the penetration and retention levels of the chemicals could be defined in an Alternative Solution, but this would require submission of evidence demonstrating durability equivalent to H3.1 radiata weatherboards before this product could go to market. Was evidence supplied with Hermpacs CodeMark applications and was this evaluated by the Certification Body? I don't know because that information isn't available, there is no reference to it in the certificate.

Together, these certificates look to me (on the outside with no way of looking in) like they are riddled with appraisal errors and shortcomings that have graciously provided Hermpac a loophole to supply larch into the natural cladding market.

Hermpacs marketing machine certainly recognises that natural timber cladding is in demand, either uncoated, or only coated with oil or stain. There is definitely commercial advantage in certified products made from timber species that are not currently allowed by the Acceptable Solution, NZS 3602:2003.

Indeed Hermpac have produced a wonderful colour brochure that portrays the warm attributes and good looks of natural timber weatherboards made from their Larix sibirica. Their CodeMarked Larix siberica can be used without paint. Or perhaps only DuraLarch, not actually the species itself? Hang on, the page says species information. I wonder what a Building Consent Authority (BCA) would do when presented with an oil coated Siberian larch clad house with a drained cavity, if that larch was supplied from a third party? Would the BCA accept this species without question because Hermpac have been selling it for years?

Digging a bit deeper, there might be an explanation for the shortcomings in Hermpacs three CodeMark certificates. It appears that Hermpac's CodeMark certificates are copied from BRANZ appraisals that date back to 2014 (before the CodeMark scheme and rules were put together):

In these four appraisals the products are all cavity-based timber weatherboard external wall cladding systems for buildings. The products are all to be finished with a penetrating oil stain or an exterior paint system. The Hermpac Weatherboards themselves are manufactured from Canadian Coastal Western Red Cedar, DuraLarch (Siberian larch heartwood) and Ashin-Dura (Western Hemlock). The Cedar and DuraLarch weatherboards can be "supplied unfinished for site finishing with stain or paint prior to installation", whereas Ashin-Dura weatherboards "are treated to Hazard Class H3.1 and must be paint finished only".

What these appraisals all say is that "in the opinion of BRANZ, the Hermpac (all four appraisals) Weatherboard Cavity System, if designed, used, installed and maintained in accordance with the statements and conditions of this Appraisal, will meet the following provisions of the NZBC: Clause B2 Durability". These appraisals do not reference any Verification Methods used to prove durability of Siberian larch with a stain coating for timber weatherboard external wall cladding. I'm puzzled by this and actually wonder if BRANZ were even aware that larch is not an Acceptable Solution for stain-finished weatherboards. If so, they might not have realised that proof of durability performance was required. Or did they verify durability performance but just didn't publish the proof or any reference to it? There is no reference in any of the BRANZ Hermpac appraisals to such information, yet this is required by the regulation because it would form the basis for certification. Noting that product certification must comply with the building code, was it only BRANZ's opinion on which Global-Mark based their decision to CodeMark certify the three weatherboard systems that use oil-coated larch? If there were an adequate audit process, this information would be available in the Evaluation Report for review.

So was the CodeMark Certification Body on the ball, or were they just rubber stamping the previous work by BRANZ without considering code compliance? That wouldn't be a good look. But I don't know because although the evidence might actually exist, the certificate has no reference to it. I can't review the appraisal nor the evidence. This needs fixing.


Abodo hold CodeMark certification for two untreated timber cladding products:

  • Abodo's Tundra product, made from Douglas fir heartwood
  • Abodo's Vulcan product, made from thermally-modified pine

Douglas fir heartwood is of lower durability than larch so is not allowed for cladding under NZS 3602. The Alternative Solution would therefore need to prove that Douglas fir heartwood is of sufficient durability for weatherboards, even if paint-protected.

Abodo actually have a CodeMark certificate for their Weatherboard Cladding product that doesn't even list species. The document doesn't list much at all but does reference Abodo's manual dated Jun 2016. Their manual states that coating is to be done according to coating manufacturer's instructions but doesn't state that paint coating or priming of their CodeMark products is mandatory for compliance with the building code.

UPDATE, JULY 2021: Abodo inform me that they have improved their certificate to now conform with the regulations and have achieved building code compliance for their Vulcan thermally modified cladding by proving durability performance is equivalent or better than macrocarpa heartwood.

Instead, equivalence is claimed to an acceptable solution in NZS 3602 that does require paint coating (H3.1). In their manual, Abodo state that their thermally-modified radiata cladding "has been assessed for minimum H3.1 durability and approved as an acceptable alternative to species listed in NZS3602:2003 Table 2A". However, timber treated to H3.1 MUST be coated with primer and then at least one top coat of paint (as per NZS 3602:2003). Therefore the cladding product should either be paint coated or Abodo should claim equivalence to a specific acceptable solution that doesn't require paint protection. So how did Abodo convince the certifier that their glulam thermally-modified weatherboard (Vulcan+) product wouldn't need painting? The evaluation and grounds for compliance are not stated in either the certificate or the manual. The consumer really should know how or if they conformed with the durability performance requirements of the building code to gain their conformance certificate and commercial advantage. Perhaps the vertical grain orientation in their glulam boards enhances durability, but was proof provided that this is indeed the case? If the quality of their product was high enough to sway the opinion of the certifier, according to the CodeMark rules this would then need to be documented. This certainly isn't referenced in the certificate or manual as required by the regulation. The requirement is actual evidence of durability performance.

For their Tundra cladding, Abodo's manual states that Douglas fir heartwood "has been assessed an acceptable alternative to species listed in NZS3602:2003 Table 2A", apparently by Scion. Was this claimed assessment by Scion an expert opinion, or actual proof that Douglas fir heartwood is good for at least 15 years as unpainted cladding?

So can Abodo's Douglas fir heartwood be used as cladding without paint coating? Well, in the Abodo manual there isn't actually a requirement that Douglas fir heartwood be paint protected.

Now, I don't have an issue with Douglas fir being approved for cladding. My issue is that the process for this requires evidence that proves it will last a minimum of 15 years as cladding. Douglas fir heartwood is not a proprietary product so whatever the evidence was that Abodo used to get their product to market, anybody can use. The floodgates are opened and we don't even know what the evidence was.


Certification of products in the absence of adequate scrutiny results in products that fall through the regulatory cracks to give the applicant commercial advantage. None of the CodeMarked products described above reference the basis for code compliance and none of them reference a Verification Method or Alternative Solution. In all cases the appraisal system appears to have failed the consumer, who has a right to know that the product they are buying conforms. The manufacturers claim nothing more than an estimate of serviceable life. But what the consumer and regulator both require is proof that the product performs, a true assurance that the product's durability is code-compliant. Is CodeMark providing that?

My gripe is that I can't review the actual basis for approval for any of these products. I stress that an opinion is not what gets a new product past the conformance mark, this isn't the Wild West. What is required is evidence that proves that durability performance is adequate.

Heres the rub – by giving a proprietary product commercial advantage without disclosing the means for such advantage, either a monopoly is established, or the floodgates are opened for copycat producers. This occurs and nobody even knows why. So will the next person that comes along be treated the same by a Certification Body if the methodology is not disclosed for their previous decision?

The Alternative Solution should be available for review by me, by the applicant's competitors, by BCA's, by the regulator. That is called transparency. Transparency is required for scheme integrity. A line must be drawn in the sand. Even competitors have a right to know what evidence was provided that proved adequate performance of a product. The actual method used to prove durability should not be withheld from competitors, because this would amount to unfair advantage. If the product is approved, the test method must then become the benchmark for me or anybody else who wants to, for example, introduce a new species treated to H3.1 into certification. There must be a level playing field. Sure, the methods used for manufacture of proprietary products can remain confidential, but the test methods used must be transparent and made available for scrutiny. Legitimate decisions on compliance must not be judgment calls made by the Certification Body, but a pass or fail based on code-compliant Verification Methods.

Can the certifiers' decision be called into question? Can we rely on the regulator to review all Evaluation Reports for code compliance? Is it okay to pass conformance evaluation to third parties without any means for independent audit of the decision? How can certifiers be held accountable for their decisions? The answer is that there should be sufficient regulatory and technical oversight, with mandatory audit of the basis for every certifiers decision.

Dean Satchell
Chair, Farm Forestry Timbers Society

Disclaimer: Personal views expressed in this blog are those of the writers and do not necessarily represent those of the NZ Farm Forestry Association.

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