Rotten to the Core — readers respond to publisher’s claims


The article Leaky homes: Has New Zealand learnt its lesson? (Building Today, February 2018) disturbs me somewhat.

I entered this industry in 1979, and have seen all sorts of changes backwards and forwards throughout my time in the industry.

I have had experience in most aspects of it venerable industry, from light commercial, shopfitting/office fit-outs, modular homes, residential new homes and alterations.

I have been self-employed and have employed staff. I was a member of the Registered Master Builders Association, and have progressed to the “dark side” of building compliance.

The article infers that timber treatment is the saviour of the industry, which I feel is misguided.

It doesn’t matter what you use for timber or the treatment of it within a building — all you need to do is keep the moisture out.

The biggest problem we have in New Zealand is the false belief that a cavity will mitigate any shortcomings of a deficient cladding — or, more important, leaky windows.

As an industry, we are seen to put a lot of work into fixing or mitigating leaking aluminium joinery. I don’t know why we don’t fix the problem at its source?

The use of untreated timber in the 1990s coincided with the advent of the dreaded polystyrene claddings and other so-called monolithic-type finishes (fibre cement sheets), and the reliance on sealant as the fix-all for waterproofing.

As for the desire to have a Mediterranean look, I always felt if you wanted that look either emigrate or put up with the risks.

Our forebears used mechanical flashings as a defence against possible problems — or, in the cases of masonry veneer, a substantial “wet” cavity. The wet cavity was there because it was recognised it leaked in the first place!

I feel the industry is in decline as we indulge the franchised model of home building which fragments the industry to the point where any numbnuts can assemble a home and blame the next contractor for any issues.

In my line of work now, I still deal with inexperienced designers thinking their job is to get away with as much as possible, and builders who have no basic concept of how to make a building weathertight.

We need more and more information on the consent files now because the contractors need a book of instructions on how to do it — as well as the inexperienced inspectors needing the same instructions to know what to inspect.

The industry is in disarray, with councils too scared to take responsibility for their decisions and hiding behind legislation that is drawn up by the next new MBIE team leader who wants to make his mark on the industry.

We need to get back to basics, train our tradespeople better, stop the silly approval of risky claddings, and get some common sense back into our cladding systems.

I see a lot of overseas cladding and construction systems being used in New Zealand without the full knowledge of how to manage these systems on an ongoing basis.

The basic New Zealand home works perfectly fine in keeping moisture out. The direct fixed, untreated timber-framed villa of old is still standing and, apart from its obligatory maintenance requirements, will see most of us out.

We need to take stock of what has been used in the past, and must surely start to wonder why we needed to fix something that was not broken in the first place.

Leaky buildings are a product of legislators meddling in an industry by opening the gates to unqualified people making bad calls on the unsuspecting general public.

Just because a lab test showed borer was less likely to eat bone dry timber, then tell me why you will find borer in a bone dry 100-year-old timber villa with no moisture in it!

As I said, keeping moisture out is the first and foremost requirement of any cladding, as building timber treatment is a band aid when the claddings leak.

Fix the claddings then the second problem goes away! Fancy designing a home to leak and saying that treating the timber will fix it!

Common sense doesn’t seem to raise its head high enough at times.

Anaru Johnson


I must take issue with a recent advertorial about the new publication Rotten to the Core (Building Today, February 2018), which contains a number of inaccurate statements.

As Chair of the Standards committee that reintroduced the treatment of most framing timber in 2003, I have a reasonable understanding of the history of timber treatment in New Zealand.

Boron treatment of timber was introduced in the mid-20th Century to reduce the incidence of insect attack in softwoods, and not to prevent timber rot or mould growth.

Until more recent times, the only known and effective treatment against rot, which was specified for fully exposed or buried framing timbers, was CCA (copper/chrome/arsenate).

The key argument put forward by timber companies in the early 1990s, who were proposing that kiln-dried and machine-stress graded radiata pine framing be left untreated, was under the false premise that framing timber always remained dry and, therefore, would be unattractive to boring insects.

Timber rot was not considered as an issue by the then Standards committee which, sadly, still had faith in our industry’s ability to build houses that didn’t leak.

Research through to the beginning of this century showed that certain levels of boron (and some other treatments) were effective against both insects and timber rot.

My committee agreed, and NZS3602 and associated Standards such as NZS3640 were duly amended.

Tragically, wet and rotting framing timber has become both an issue and a disaster. As is still being revealed today, if walls leak and water gets trapped inside, framing timber will, over time, rot and grow dangerous moulds, whether treated or not.

It should also be recognised that many of the so-called white plastic “tents” are there to provide a dry working environment for house alterations and, in many cases, have nothing to do with rotting timber.

Don Bunting

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