Monday, 16 November 2009

LEAKY HOMES, Part 2: What’s going on inside your walls?

“Q: What’s your cladding for? 
A: It’s to protect your building paper.”
- Old builders’ joke

THERE’S AS MANY MISCONCEPTIONS OUT THERE about what makes houses leak as there are so-called “experts” willing to take your money to find them.

First of all, all houses leak.  Always have.  It’s all about pressure: apply a high wind outside and you get high pressure.  Close all your doors and windows and on the inside you get low pressure.  If that reminds you of a vacuum cleaner, then it should. It’s pressure differences like this that make your vacuum cleaner work – and when the wind and pressure difference around your house are high enough, your weatherproofing systems are going to suck.

There’s nothing much you can do about that.

bayNo house would survive under water – that seems pretty obvious.  Even if it’s painted yellow, a house is not a submarine. Unlike a submarine, which is built with hermetic seals, then all houses no matter how they’re built are going to let water in behind the “outside skin” – which is what we call “the cladding.”  The point is to make sure the water does no damage while it’s in there, and it gets out just as soon as it can.

dd For decades - nay, for centuries - most houses managed to do that pretty well.  A decade ago in New Zealand we were building “mock Tudor homes” with modern materials, and they leaked.  Yet five centuries ago they were building real Tudor houses (like that one on the right there) with branches and twigs over which was daubed a mixture of clay and sand and dung. Yes, dung. They called it “wattle and daub,” and surprisingly enough it didn’t leak, or at least didn’t cause major problems when it did. 

110263519_full And houses built here in New Zealand at the turn of the century with stucco over asphalt-impregnated paper – houses like that next one on the right -- they didn’t leak either, or at least didn’t cause major problems when they did.  Yet last decade we were building “modern stucco” houses, and they did.

So what happened? For years we had no major problems, so what changed down in our neck of the woods that all of a sudden changed things? That’s the big question, isn’t it.  What changed in the physical structure of your outside walls that caused water to get in and not to get out – and to cause real damage while it was there?

Well first of all, it wasn’t deregulation that caused all this.  I talked about that last Thursday.  But  quite a lot did change that  required bigger changes, but those changes never happened.

There’s probably some rule that someone can quote about this.  Change one thing in a whole system, and other things can change to take account of that.  Change everything in a system, and it takes some time to settle down – or to notice the ill effects of what just happened.  In the early nineties, almost everything changed inside your outside walls, but other things never changed to allow for them.  Something in particular. You’ve heard all the buzzwords: dry-frame, no eaves, Harditex, cavities stuffed with insulation, failing cladding systems, moisture content, stachybotrys . . .   Let me see if I can explain simply what these all mean, and what caused the problem – and why no-one’s talking about it.

Weatherboard-Timber_Window SO LET’S TAKE A LOOK at a typical outside wall – or at least a wall as you would have found it freshly built about ten to fifteen years ago. And to make it more interesting, let’s do it with a chain saw.

Let’s say you’re outside in your garden with your chain saw in hand, and you’re casting an eye over your house.  Look up, and you’ll see the eaves – the part of the roof that hangs over the walls. Some of the houses that leak don’t have these, but just as many that do, do.

Now turn the saw on, and take a cut through your house’s outside wall. The first thing to feel the saw is the cladding.  Depending on your house this might be any one of weatherboard, plywood, corrugated iron, brick or concrete block (which are going to cause major problems with your chain saw), or plaster or textured coating on fibre-cement board (which were what caused most of the problems with leaks).

Solid Plaster wall frm NZS 3604-1990Cut through your cladding, and the second thing to feel your saw is your building paper, which sits behind the cladding. Remember: your cladding isn’t a a hermetically sealed skin. Your cladding sits out in the high pressure zone, and sitting behind it in the protected lower-pressure zone is your building paper – which for decades was the plain black bitumen-impregnated kraft-based building paper that everyone knew and loved. And contrary to popular, and even “expert” opinion, it’s your building paper that’s always been your major line of defence when it comes to weatherproofing.  Your building paper is supposed to allow condensation out of the house, and stop any water that gets through the cladding going into the house  – and until ten to fifteen years ago it was doing that job damn well.

And don’t discount the amount of water getting through the cladding either: when it’s high wind and high pressure  outside your walls, and low pressure inside, then you’re going to get water behind your cladding.  Always have, always will. But install your building paper right, with proper laps and flashings in the right place, and you’ll make sure it doesn’t get inside your walls, and it gets away before it causes damage.

So let’s keep on cutting, and if we do we’re now going to start cutting into the walls themselves.  Your walls are made up of vertical sticks of timber (“studs”) between which are nailed some horizontal sticks (“nogs”), to both of which you nail your cladding and staple your building paper, and between which you generally stuff insulation to keep you warm.  If you keep cutting you’ll eventually get through this space (it’s only four inches wide) and your chain saw’s going to be cutting through the gibboard lining and into your house’s best room.  Careful you don’t damage your sideboard.

SO THAT’S YOUR BASIC WALL, which now looks pretty messy after it’s had a chain saw going through it. 

Now in the early nineties there were big changes from inside-to-out of that wall, changes that had nothing to do with “deregulation” (which is pretty much just the catch-cry of the cringingly ignorant) but which between them caused a “perfect storm” inside your wall – and I hang my head in shame at using that phrase, but it’s the perfect description for what happens when a whole bunch of things come together to cause an $11.5 billion problem.

Let’s look at all the changes.

1. Working from the neck up?
We share the stud-frame technology I’ve described here only with North America and with parts of Scandinavia, and our own methods are largely unique to us. So it’s moderately unusual, and for the most part the skills for it need to be learned here.  That’s one point.

paper Here’s another. A timber-frame building is a ‘thought-built’ building. To build a timber-frame house successfully knowledge, skill and understanding are needed; constructing them properly requires that the builder work from the neck up – thinking as he installs flashings and building paper and other piece of weatherproofing kit; thinking about water paths, load paths and the like. About where water will be coming from, and where it’s going to go. 

Sadly, many of the current crop of builders can’t do that much (even those “master builders” with walls full of certificates) because what they learned at their schools wasn’t always what they needed to learn. The complete story of the failure of New Zealand’s apprenticeship system is still to be told, but the body of knowledge that was once widely shared and passed on through the apprenticeship system, and on site by informal ‘mentors,’ has broken down.

Here’s another point. A timber-frame building is a ‘thought-built’ building, and most of the current crop of architectural detailers never learned how to. Some of the early examples and highest-profile cases of leaky homes, such as the 97-apartment Eden Two complex in Auckland or the 44-unit Marion Square Project in Wellington, were designed by registered architects (architects who won awards for them) but were detailed by young architecture graduates trained in schools that know next to nothing about construction technology; and they  were put together by “master builders” who didn’t know much better. The results are predictable.

imageHere’s just one example of a particular problem at Eden Two: Un-tanalised dryframe timber was specified and installed in exterior cantilevered decks. The deck timbers you see in the picture at left, the bearers, were cantilevered out to support the decks. To stop water ingress to the balcony framing, building paper should have been taken over the top of the decks’ parapets and lapped under the building paper of the main structure. It wasn’t. But even so, if they bearers had been tanalised, these important structural members could still have survived. But they weren’t tanalised. They were dryframe.

The graduate architects simply read off their tables what they needed to do, the master builders erected what they had to do, the council’s inspectors okayed all that was done . . . and no-one, not on any of the ninety-seven units erected, ever looked at either the improperly installed building paper or the untreated bearers and said “That’s not right.”

The beams were specified by registered architects, installed by master builders, and inspected in accordance with the Building Act, yet no-one at any stage noticed the difficulty (and nor do they note the difficulty now when people say requiring architects to be registered and builders to licensed is going to solve similar problems in the future). The problem was not one of ‘insufficient regulation’: the problem was that each person who was party to these decisions was either untrained, uninformed, or simply unwilling to stand up and point out the problem.

2. Timber not worth the name
The studs inside your wall changed.  Since the fifties your studs have mostly been built from plantation radiata pine, but two things changed recently to change what that meant.

First of all, for many years the radiata pine was always treated with boric acid, mostly to protect against insects like borer, but it turned out that “poking the borax” also protected against rot.

Second of all, while the pine used to be cut from trees that had taken longer to grow, more recent faster-growing timber turned out to have bigger “cells,” which means less strength, and more prone to rot.  An ideal time, then, to introduce “dryframe” untreated timber in your outside walls.  Or not.

Public choice theorists talk about how Bootleggers and Baptists will often find common cause – the “Baptists” calling for bans on things like alcohol because they don’t like them, the “Bootleggers” supporting those calls because the bans raise the price of their product. Something similar happened here with dryframe:  chemophobes who claimed the boric salts were toxic and were poisoning the occupants joined forces with the big timber companies who wanted to charge more for selling less timber. The result was “Dryframe” – untreated timber that takes on water more readily, holds mould more easily, and rots far more quickly.

The vast majority of houses now being condemned were built with dryframe timber.  But that’s not the biggest story here.  That still doesn’t explain why so much water got in.

3. Silicone

Silicone isn’t just popular in Hollywood, it’s been all the rage on New Zealand building sites for the last twenty years.  Nothing wrong with that necessarily, but what happened was that folk forgot what flashings and building paper were for -- which was to remove the water that had got behind the cladding -- and they tried instead to use silicon to “face seal” the outside skin of the cladding; “face seal” it so that no water could get in at all. Can’t be done. A building is not a submarine.  And because too often the silicone was used widely, but not too well,  instead of keeping water out in too many cases it was actually blocking drainage paths and keeping water inside the building envelope. Remember the TV ad for example in which the late Augie Auer ran a line of silicone underneath his window sills?  He wasn’t stopping water getting in, he was stopping it getting out.

So over-reliance on “face-sealed” systems was a problem. But this is still not the biggest story here. That still doesn’t completely explain why so much water got in.

4. Stuff the wall cavities

Live in an older New Zealand house in winter, and pretty soon you’ll complain about the draughts.  Newer New Zealand houses don’t have the draughts because they have insulation in the walls, stuffed into those cavities between the studs. This is all the better for home-owners who are kept warmer in winter and cooler in summer – and for would-be National Party Prime Ministers, who offer the promise of better insulated homes to bribe voters with their own money – but not for the wall framing, which is all the worse now for the ability of wall framing to dry out if water does get in.

But that’s still not the biggest story here.  That still doesn’t explain why so much water got in.

5. Those aftermarket add-ons

Increasing wealth means increasing add-ons to the outside of your home.  Fancy installing Sky TV? An awning or two? A new pergola? All of these aftermarket additions add to the liveability of a home, but they’re all are much more difficult to install properly in a ‘plaster-look’ home – especially when the look is so convincing that installers often forget just what they’re screwing into. But penetrate the cladding of a monolithically-clad home, especially if the water can’t get out again, and you’re going to cause problems, just as many of these later additions have.

But that’s still not the biggest story here. These after-market bolt-ons caused some damage, but not all the after-market bolt-ons in Christendom caould cause the $11.5 billion catastrophe that now confronts the country’s cheque books.

6. Those dedicated followers of fashion

‘Tuscany’ is in. At least, it was. Tastes have changed very quickly now, but for a while there faux Tuscan was de rigeur. But Tuscany itself has a very different climate and totally different construction methods.  In Tuscany they have plastered solid masonry buildings that artisans have been building for centuries – whereas here in New Zealand designers tried to emulate them using timber stud walls, which is something very different. 

But where there’s demand there will always be supply.  Cometh the hour, cometh the building systems – the most popular of which was James Hardie‘s Harditex – a medium-density autoclaved board made with wood pulp and cement that was used to back monolithic claddings. That’s what’s behind most of the “Mediterranean” looking houses you now see around the place with plaster walls, big entrances, ands tarpaulins and scaffolding all over them.

Despite the obvious problems with such a system, everyone at the time looked at the big BRANZ-approved tick this system had gained, and went to work with a will.  After all, if it’s good enough for BRANZ – whose slogan used to be “BRANZ Appraised: Specify With Confidence!” – then surely it was good enough for Joe and Janet Home-Owner.

Well over two-thirds of the houses with leaky home problems were built with this system, built with a material systems that didn’t quite stack up, by installers and regulators who didn’t always understand the building science behind such buildings:

  • Water got in, as it always will, but it couldn’t get out of them because the plaster was taken right down to the ground.
  • And instead of accepting that water would get in past the cladding and then detailing the system to suit, the “Tuscan look” called for “face sealed’ systems, and almost forgot about the building paper and its associated flashings altogether.

So the building paper was still there, even with this system, but it had often been forgotten about – and something else was going in inside the walls that meant even when it had been installed properly it was about to disappear.

That something was a mould called stachybotrys, and it doesn’t just eat children’s lungs, it also consumes building paper. That is the bigger story here, and it became a bigger story than it needed to because of one other change that happened in the decade before the nineties.  It involved asbestos.

6. From asbestos to wood pulp

Asbestos-Cement Joints The use of asbestos goes back more than 3,000 years. Its stability, high tensile strength and resistance to chemical and moisture-induced degradation made it an ideal fibre to be used in James Hardie’s fibre-cement “Fibrolite” boards, sheets and “HardiPlanks” – and the many fibrolite buildings and baches that still inhabit the country’s beaches are a testament to just how stable Fibrolite used to be.  When I first started building, we were still cutting up sheets of “fibro” with our angle grinders, and throwing the off-cuts into fires to hear them explode.

But in the early eighties it became clear even to the miners and manufacturers of asbestos that it was killing people. Fact is, it had been known since 1906, but the miners and manufacturers and other users of asbestos were reluctant to concede the point publicly, so when asbestos mining finally ceased in Australia in 1983 they had to quickly cast around for a replacement to use in their fibre-cement sheets.  What they came up with was wood pulp – cellulose fibres that were asked to do the same thing as asbestos, but don’t.

Fibre-cement sheets used to be stable.  They used to resist water penetration.  Now they don’t.  Get water in behind a snugly fitted medium-density fibre-cement board these days and it’s going to soak in there for the long term.  It’s going to soak in, it’s going to incubate, and it’s going to emerge after a short time as stachybotrys. And so it has.

7. From building paper to no building paper!

None of the changes mentioned so far would have been fatal on their own.  If water got in, it should have been protected by the building paper.  If the building paper was badly installed in some few places, it still would have protected the home-owner in every other place. (Even on the Eden Two apartments, the installation errors only occurred in the same one or two places on every apartment).

Remember that building paper is that black stuff that goes around your framing before the cladding goes on. Some years ago when I began working on building sites I was asked the standard joke. Q: What’s the cladding for? A: To protect the building paper. The reason it was a joke was that everyone understood the punch line.

But what protects the building paper when stachybotrys does come a’calling?  Then that’s no joke at all. Stachybotrys is the toxic mould you hear the most about. As one consumer website explains, Stachybotrys chartarum is “a slimy, greenish-black mould that grows on moisture-laden materials that contain cellulose [or wood pulp], such as wood, paper, drywall, and other similar products.”

Stachybotrys just loves the sort of cellulose-rich fibre that can be found in paper, carpet backing, wood fibre board such as MDF . . . and in today’s fibre cement sheet. As one learned academic paper explains,

“fungi possess the ability to degrade lignin … (Blanchette 1984; Eriks ksson on et al al. 199 1990). This is a sought ought after effect especially by the pulp and paper industry, as selective … fungi not only have a bleaching effect of the wood pulp … they further cause, through their degradative action, a loosening of the cells.”
et al al. 2003).

Sought after it might be in the pulp and paper industry, but not sought after at all in the building industry!  Particularly not when the very same cellulose-rich fibre found in Hardie’s fibre-cement boards, and used as a backing for most of those monolithic claddings, is also used in the building paper behind it.

When that’s the case, and you get water in behind the cladding, then can you take a guess what you’re going to find? 


That’s right. No building paper.  If you take a close look at that picture above, which comes from a building built by master builders and designed by registered architects, and which is clad with James Hardie’s Harditex over which a solid plaster skin has been applied, you’ll see that what used to be the building paper protecting the building is now those few scraps of paper as brittle and ineffective as an All Black defence under the tutelage of John Hart.

It’s just not there any more. It’s been eaten away. As you can see, the studs in the picture above have already been replaced preparatory to a reclad, but the building paper that used to be the home-owners’ primary protection against the weather has just disappeared. It’s been vaporised.  It’s been eaten up – just like those home-owners’ dreams, and their life-savings.


It’s a fairly simple formula here, one known about for years in the pulp and paper industry but not publicly at least by those in the building research or fibre-cement industries – a simple formula that looks like this: in the presence of wood pulp, building paper plus stachybotrys equals . . .  no building paper.

If you want to know what’s been been going on inside so many New Zealand walls over recent years, then that’s it.

And if you like your stories simple, then that’s about as simple as it’s possible to make this one.

And the story has another fairly simple back-story – another story that remains still to be told, but one appropriate to a story about cladding since the phrase that springs to mind here is “cover up.”

Because the big story here, which I haven’t seen addressed anywhere else before and which is another one for investigative journalists to get there teeth into – if there really were any here in New Zealand – is this: answering the question “Who knew about this before it happened?”

It’s a fair question because the big players both have past form.

Just as the research on asbestosis was out for years before being publicly acknowledged by manufacturers – acknowledged only in the wake of a series of expensive legal suits for which governments are still bailing out their cronies in the big companies – so too has the research been out there for years showing the effects of stachybotrys on cellulose fibres, on wood pulp and kraft-based papers.

And just as the government was able to protect the Building Industry Authority’s bureaucrats from harm’s way by changing its name, so too you’d hardly be surprised if they did what they thought they needed to do to protect their bureaucrats at places like the so-called Building Research Association.  After all, they’ve already made the company once called Building Technology Limited 1995 disappear, which was once (see below) the “company wholly owned by BRANZ” which issued all those nifty appraisals back in the day, and which are now worth less than the wood pulp on which they’re printed.

So who knew, and when?  Did James Hardie?  Did the government’s so-called Building Research Association? What did they know, and when?

And how come it’s builders and designers who are getting the blame for all this, and builders, designers, rate-payers, tax-payers and home-owners who have to pick up the tab?

I think we should be told, don’t you?

  • Earlier in Part 1: The myth of deregulated building
  • Coming next in Part 3: How everything that’s been done since the problems were discovered has made life more difficult for almost everyone.

* * * * *

All care & no responsibility? The front page (below) of one of many failed appraisals issued by BTL “a company wholly owned by BRANZ,” which is a government quango. This appraisal, for Duraplast on Hardibacker, is for one of the more high-profile leaky home failures. BTL no longer exists in that form, and the “researchers” at the government’s Building Research Association of NZ continue to shirk responsibility . . .

BTL_Appraisals-1995 BTL-Duraplast-Hardibacker


Berry said...

Bloody well done, Pete. A story that desperately needs to be told. One issue you may want to also raise is building physics, heat transfer and condensation, explaining that any and all airborne moisture created in the nicely warm insulated interior will eventually condensate on the coldest non-permeable surface, i.e. the building paper where it meets the studs, this providing a nice continues layer of moisture throughout the winter months. Secondly the old practice of drilling the nogs, all the way through to the topplate, which was abandoned under fire regulations, this of course added to now stuffing the walls with sponges, to make sure that any and all moisture is well retained within the cellulose sticks that we call timber.

By the way, many moons ago a heard a talk by a joker who used to work in a research institute for the wood and timber industry, who practically swore an oath that he had attempted in vain to discourage his bosses from certifying and promoting to stop boric treatment, precisely for the reason that he KNEW that rot would occur. I heard this in a forum, the organizers of which you would be very interested to know.

PM of NZ said...

Excellent series PC.

Silicone sealants like Sealastik should be banned as an approved building material.

Having spent a previous life trying to to keep salt water out of upperdeck electrics and electronics on ships, it is utterly useless as a sealant. At best it could be called a gasket material, for that is what it becomes when thermal expansion separates the silicone from the substrates. Even when the box cover is screwed/bolted shut, water still gets in. Water and mould migrates between the silicone gasket and the substrates within days of being applied, even with best of applications. Just have a very close look at the mould around your bathroom / shower silicone sealed edges next time it is not all steamed up.

What is required is the expensive marine grade sealers like Sikaflex that actually bond the sealing material to the substrates. Sikaflex sticks like the proverbial and is extremely flexible. Never leaks again.

Although, in house construction, I firmly believe that if silicone sealers are required, the build is not right. The adage about protecting that building paper is so true.

Having said that, it still does not fix the idiots like you allude to where they are trapping water in the envelope.

Anonymous said...

Now if only MSM would pick uip on this article. You have put into writing what many people who are on the end of litigation directives are now coming around to accepting how you succinctly describe events and decisions as the path which lead to them being shafted. But unfortunately they won't, because they are all lapdogs, imbeciles, corrupted sycophants, or just too plain retarded to know a good story when it smacks them in the face. The recent decision to abort investigative journalism by APN will only further reinforce the above memes.
Your point about unintended consequences appears to raised and reinforced the motif that what goverment legislates against, will invariably end up in resulting in more of those outcomes.
James Hardie are crooked as they come. The Australian Govt had to bail them out, because they stupidly let the buggers re-incorporate in the Netherlands, while diestablishing their Australian Head Division. Thus there is no real entity with which they can actually prosecute, because it has written off its historic obligations. The Australian Govt whould nationalise JHH's Australian operations given that is all the places are worth. At least they will get back some of the Aussie Taxpayers money.

JHH are the prime culprits in this travesty, and for them to avoid their obligations by ripping houses to pieces and measuring the distance between fixation nails, then measure every one of those same nails until they find 1 anomaly which was outside the stated 150mm distance, and x length clefthead/flathead nail, and blithely state, "not our fault, you didn't adhere to the fixation system", is beyond despicable.
It was Labour in government that gave us the disetablishment reestablishment (ala JHH). Their shonky morals and actions (see Crown vs Philip Field) that allowed this cover up to occur, and no doubt political pressure over the decision to absolve the BIA from actions taken under BRANZ, to legitimize this affront to house buyers Nationwide.
Fletcher industries have probably managed to distance themselves from any comeback by hiving off the various divisions and lumping any liabiltiy with the now non trading Fletcher Forests. CHH has had its assets divested and is no longer the company it was when this saga began.
Ultimately it was BRANZ/ BIA that bought the bollocks hook line and sinker from those 3 companies and legitimized the inherently broken systems, despite evidence in 1996 from the Canadian Building authorities that similar systems would lead to this type of abject failure, and so unfortunately for me, and the other 3/4 of a million homeowners who don't own these pieces of rotting rubble should pay for it through our tax dollars.
A former high ranking member of a provincial property investors association and lawyer advised me once that there will come a time in the future when people will look at the period when a house was built (essentially the period you acsribe as that which correlates with the existence of BRANZ until 2010), and they just won't buy it. The entire era is tainted. It will be up to the owners of non-affected houses to prove that their pride and joy is not a wet-house. Probably on the soundest pieces of advice I have ever taken.
Joe Monolith householder is getting the shaft bigtime, and it appears no one will pay the piper.
One aspect that you have failed to thus far to point out is the polystyrene-tecture coat house solutions which also happened within the regulations are also inherently flawed. I have heard on one incident where the local building authority ordered that one such house be reclad as it was leaking, and upon the contractors stripping the cladding off, found that rats and ants had in fact eaten all of the polystyrene, and that the shell surrounding the house was a flimsy layer of plastic, floating in the breeze. I think it was likely the only thing keeping water out of the house in this case was the building paper. How many more buildings of this type of constuction will have the same problems?

Anonymous said...

A recent discussion I had with a builder/ building company about an intended build was how brick cladding systems haven't changed and aren't affected by the wethouse syndrome. Is this true?
What are metal framing systems like? Do they leak?

Anonymous said...

Thankyou. I grew up planting pine trees in the early 60's and learnt from watching big old grandady pine stumps rot out in two years, that pine timber had to be treated.
I have had a lot to say on other blogs about this subject and the shabby way the govt et al are treating and have treated the unsuspecting.
I deal weekly with home owners that are affected and in one case of an apartment I currently have their possessions for a second time. They leak from the top down so every floor has its day.
Clark and her dishonest partners in crime at parliament have a lot to answer for in this debacle.
Worse still is Williamson's offer the other day for the Govt to pay 10%. What a joke. They are offering 10% and taking back 12.5% in GST so they make 2.5% on their shabby transaction and then of course there is things like PAYE, tax on company profits and so on.
Someone has asked about steel frames. Watch this space. Two problems that I can see. Earthquakes. A descent ground bending movement will distort the steel and it will not return to shape. Panel beating won't work so replacement will be required. Lots of bending= house stuffed.
Water and especially salt water.
As has been pointed out water gets everywhere. It carries salts and the salt will corrode the light galvanizing in side any frame. Take a while but have a look at any iron roof near the beach or in Rotorua and see what happens.
Ask the iron companies if they will give any guarantee with their roof iron and what guarantees they will give with steel frames. Once again these are a dry country product.
There is an old old saying , "Rust Never Sleeps"

Anonymous said...

Nice post again - good to see the issues put out there. Especially the big question - investigation into who knew about rot in dryframe timber & behind monolithic claddings (esp. Harditex)?

Question - if fungi rot fibrous products like Harditex, paper & wood, then why didn't they rot the building paper between drywall linings and timber weatherboards? All wood or pulp products, but no rot?

Was it the combination of pulp products with silicone sealants & insulation cutting down on drainage? Or a change to the building paper composition? (which you seem to hint at).

Monsieur said...

Good post Pete.
I'm not sure about your "Bootleggers and Baptists" part where you say "chemophobes who claimed the boric salts were toxic and were poisoning the occupants joined forces with the big timber companies who wanted to charge more for selling less timber."
The "Greenwash" was more likely to have originated from the building material companies themselves. The Green Party has never been against Borax timber treatments. Boric acid is fairly harmless. The only side-effect in mammals is testicular atrophy (smaller balls). I can't see the Greenies being too fussed about that.

P.S. To bung a chainsaw through a brick or concrete block house, use a tunsten-tipped chain and cut through the mortar course (it's easier to repoint after). Otherwise use a big anglegrinder. And don't forget your dust-sheets.

SHaun said...

DOes the change in building code help this (I know part 1 said the evils of regulation)

Spcifically I think about the use of treated timber and a 30mil cavitiy / air gap system for plaster houses

Hurlz1 said...

What a great summation of the leaky homes problem.

The greens need to shoulder their fair share of blame with this problem as well. They are the group that jumped up and down about any sort of treatment in timber. Timber was always treated to repel insect attack. This treatment also helped repel water. Boric treated timber could be used in exterior framing and CCA treated timber was used in exterior situations wher the risk of water penetration was a threat. To use dryframe in situations like butynol deckings was always going to invite a problem.

This pressure led to all the timber companies, appraisal firms like BRANZ chucking commonsense out the window and stupidly saying that dryframe was OK in outside walls.

Dryframe is like blotting paper, a drop of water soaks in and the next drop soaks in and soon you have a problem.

No matter how you looked at dryframe being used in exterior walls it was always going to be a problem and the govt needs to stand up and shoulder the blame for the past actions of Labour and the Greens.

The architects that specified dryframe should also have known better

The building regulations are now so over the top they are ridiculous.
Take the situation now where you have to put battens over the building paper before you fix the exterior cladding. What a massive extra cost that is not required.

The pulse of the nation

metal framing said...

This is an awesome article that is so imformative and i enjoyed reading it and took away alot of good pointers from it

Anonymous said...

Steel frame buildings may rust and deform beyond elasticity I don't know but what they do do is transmit noise throughout the structure.
You can feel the front door slam from 3 floors away.

Anonymous said...

Hey Pete,

The architectural activist that I live with thinks it would be a good idea to put up a sweepstake on which large corporate gets to you with a cease and desist order first and how long that takes to happen :-)


KazV said...

I'm on my knees grateful for this article which informs and demystifies a massive can of worms. The author's fabulous sense humour was not lost on me either. In Scotland, we would call this 'pure dead brilliant' and believe me, that's a compliment! KazV

John the Builder said...

you say;
"None of the changes mentioned so far would have been fatal on their own. If water got in, it should have been protected by the building paper. If the building paper was badly installed in some few places, it still would have protected the home-owner in every other place. (Even on the Eden Two apartments, the installation errors only occurred in the same one or two places on every apartment)."

I think you make some good points but if you think that building paper was the saviour then wait for another building failure round the corner. The problem was absorbant claddings that held moisture and transferred it through the paper/wrap and into untreated /unprotected timber. The paper was not meant to be a barrier and never could be.

We need to understand the science better and the govt should be spending the $$$ to find out the real causes and solutions to current failures (and how to repair more cheaply) instead of filling the feeding troughs at BRANZ or at least direct some building levy money to the coal face.

Doug said...

Great post,a lot of stuff 100% right.. but i think you've missed the biggest reason why NZ's buildings are leaking. In the early 90's water blasters slowly started to become the weapon of choice for cleaning.Today their use is prolific. Buildings CANNOT withstand the pressures these machines generate. Stop water blasting our houses and the leaky homes problem will be solved. If you want more info or to discuss things further e-mail:

Mary said...

Hi there,

But in the end- nothing is really done! Meditations, tribunal..More stress...and more debt from my pocket.

Victims are paying solicitors fee and still leaving in leaky houses, the guilty parts are not been prosecuted. They are still holding the same positions at City Council etc. and the all process of ripping off innecent citizens are will go again... Again paying for building consent, again fee's for surveyers etc. Where are there certified "professionals", who done their work oryginally? Went to another planet? Or go to Australia with huge profit from leaky houses development scam!

Yet- instead of goverment to clean the mess and DO THE RIGHT THINK, go after people who cause this- they fight us in the court...

What is happening here? Where is the Kiwi's spirit to take actions? Any idea's? Count me in!!!

Kiwi's stand up together and DO something about these atrocity!

Who say's "WE are the people"?

For me a silence or not taking any action is like saying " Is okey mate, don't worry" ARE YOU?

Kindest Regards

Mary ( one of the victim, who was taken for ride as weel and paid for Prendos certificate, LIM rapports, registered building inspector certificate from North Shore City Council stated: "that house is structually sound and not leaky" that was my suspensive condition on purchase in Deed of sale. And? LEAKY, rotten wood and more...) I'm saying- Enough is enought!

Action speak louder then words. No more complains or stress out- take a stand! Question remain- How?
Any good advice will be appreciate it.

Mold Guy said...

Very interesting read and story.

Good break down of the wall and how it is constructed.


KW, Taranaki said...

Excellent read Pete. I was a timber machinist and treatment plant operator in the early 1990's to mid 2000's. I well remember the debates in the smoko room about supplying untreated timber sourced from young growth forestry blocks.
The regular comment was that 'this will end in tears', and so it has. Not only was untreated pine very prone to rot and weaker, it was very unstable. Whether kiln or air dried, finding a straight piece was a hard task. A 'twist' in a 4 mtr length was very common.
Being prone to movement would no doubt have made the problem worse by distorting the wall cladding causing failure of 'silicone sealing'.
When treating was untaken in this young growth radiata, CCA was absorbed like ink to blotting paper due to the larger cell size. One can only imagine how readily water would be absorbed and retained in a 'dryframe' wall.

Our home is a 1880's cottage. Mortice & tenoned studs and plates, made from heart Rimu with no dwangs or 'nogs'. Built in a time when building permits, inspections and 'Master Builders' didn't exsist, but rather common sense when constucting to the elements obviously did. 127 years later, weathering numerous cyclones, storms, earthquakes and tornado's....she still stands proud.
This whole leaky building problem should have been addressed and fixed by the names of the people on the plans, permits and building contracts whom created the problems in the first place. The owners of these homes were trusting the names of those people on the paperwork.....simple as that.
How many of these 'architects', 'building inspectors'and 'master builders' have gone on to better things in their careers, accumulating wealth, while the home owners who trusted them have been left with heart break and finacial hardship?
Where's the responsibility? And the bigger question, who was the architect of the confusion and cover up that has dogged this issue?

reclad northshore , said...

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Unknown said...

Thanks so much for this great and valuable information.
The problem is, the more I read up about leaky homes the more I'm finding it difficult to buy a house!! It all sounds very daunting.
I do have a question that I need an answer to and if you or anyone out there can answer I would be very very grateful.
I'm very interested in buying a 2 storey house in Botany, Manukau area. The house is built in 2004 by Fletcher Homes.
The first floor is brick and second floor looks like the plaster you've been talking about.
What should I be watching out for when buying these type of houses?
And does this type of building have the same or more or less risk of being leaky, as compared to the Mediterranean looking houses (i.e built with 2 stories of plaster right to the ground)?

Hope to hear from you soon!
Thanks so much!

Unknown said...

Thanks so much for this great and valuable information.
The problem is, the more I read up about leaky homes the more I'm finding it difficult to buy a house!! It all sounds very daunting.
I do have a question that I need an answer to and if you or anyone out there can answer I would be very very grateful.
I'm very interested in buying a 2 storey house in Botany, Manukau area. The house is built in 2004 by Fletcher Homes.
The first floor is brick and second floor looks like the plaster you've been talking about.
What should I be watching out for when buying these type of houses?
And does this type of building have the same or more or less risk of being leaky, as compared to the Mediterranean looking houses (i.e built with 2 stories of plaster right to the ground)?

Hope to hear from you soon!
Thanks so much!

Anonymous said...

Very interesting reading re: leaky homes.what I need to know when re-gibing and insulating brick exterior walls, do I use building paper, or is stapling a couple of strips of strapping suffice to keep space between bricks and insulation. Ex state house built in 60's, so a good space between as well as a mesh plate at bottom. Or should I not insulate at all if it is goiong to create moisture,a corner room in winter becomes quite cold

Anonymous said...

I can name a person that worked for BRANZ who wrote the appraisal certificate for one of the plaster systems , he immediately left Branz and went into partnership with that company , his job was selling the system to councils architects and applicators , he also put together the fixing manuals , he and his partner subsequently sold to nuplex for some millions and has a stress free life ,not like a lot of building owners, maybe some journalist could track this person down and interview him, ask him what his credentials were to appraise this system and for his story , it may enlighten everyone in to BRANZ role in this saga , He would be one reason why they rebranded to limit their liabilities

Anonymous said...

That is a really indepth article. I never really thought about walls like that before :-) But on a serious note it is something to consider, especially the part about thinking that your cladding can protect from water in high pressure environments. Water unfortunately, always finds a way in

zack said...


andy said...

Truth is we haven't seen the last of this "leaky" problem. On my own jobs and any formmy clients I still use black building paper it's worked for 100 years plus. Cavity systems are not a fix I can see another problem coming with claddings failings. We don't do anything to protect the back of the cladding ie paint or second layer of building paper. And with moisture in the cavity penetrating the Claddings over time they will break down from the inside out.

MarkStonis said...

This is a nice post in an interesting line of content. Thanks for sharing this article, great way of bring such topic to discussion.

Unknown said...

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Unknown said...

What about 1960s era cement/concrete clad timber frame buildings? Any issues there i see some crack repairs on a few.