Posts Tagged construction

The Influence of Buildings Ken Collins Sep 16

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We sometimes get things appearing out of left field that proves to be thought provoking beyond its original purpose. And so it was with this video clip YouTube Preview Image of David Byrne (lead singer of Talking Heads for those old enough to remember back that far) that a friend sent to me.

In this 16 minute clip David discusses how music has been influenced by architecture. More specifically how musicians were influenced to write music that suited the building or environment they were going to be playing it in.

He explores how this has been true from the time of classical music in earlier centuries, through to modern times. One example given is the music that Talking Heads created while performing in the CBGB club,

The CBGB Club

The CBGB Club

which is shoe horned into a small downstairs bar. The music that sounds great there is lost in a big concert hall or stadium. As opposed to music that became known as stadium rock, where Queen’s ’We Will Rock You’ and ’We Are The Champions’ comes to mind.

While the clip in itself is interesting, the extrapolation of this is — how many of the things we do every day are influenced by the built environment we inhabit? And do we really create or modify buildings to suit the function? Especially when function and use changes over time.

Many of us have experienced moving into a new house, and then working out how we can fit our stuff in and how we are going to use it. Features like a big lounge for entertaining or a cozy sun drenched space that is ideal for reading, have subtle effects on the things we do, that maybe we didn’t do before.

Queen at Wembley Stadium

Queen at Wembley Stadium

Scale this up to an entire office building, a laboratory, a public space, and the influences can have a greater effect. Especially when the technology, or user needs change over time. We create work-a-rounds, or modify the scale of things to suit our built environment, often subconsciously or in subtle ways that are obviously apparent at the time.

That is until a critical point is reached where the cost of not altering the environment is greater than putting up with what we already have. Where the cost (not only in dollar terms) of a new building or a major refurbishment becomes justified.

Even buildings designed for highly specific functions aren’t immune. Think of court houses, laboratories, or sports facilities. Changing needs has an effect on all parts of our built environment, and vice versa.

The numerous unused petrol stations that now dot our roads are an example of how specialised buildings can struggle to find alternative uses, and those that have been found alternative uses sometimes seem to be an un-natural fit.

It has long been known that the built environment influences us all, to varying degrees. But to what extent, and how consciously, this happens is so often lost in the hum of daily life.

Pre-Designing Your Lab for Sustainability Ken Collins Aug 15

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VUW Coastal Ecology Lab

VUW Coastal Ecology Lab

A short time ago I was reading this article in the R&D Mag online. Titled ’Pre-designing your lab for sustainability’ it makes a number of relevant points when thinking about laboratory design. Although it appears to be aimed at university type projects the points it makes is certainly relevant to all laboratory facilities of all types. Especially where it confirms that laboratories can consume up to 50% more energy than office buildings of a comparable size.

As issues of sustainability, energy use, lifetime costs and environmental impact continue to increase in order of importance, the earlier these issues are discussed and incorporated into the working brief for any new or re-developed facility the easier they are to be realised in the completed building.

In the article it talks about the US Green Building Council ’LEED’ programme, or Leadership in Energy and Environmental Design, as an internationally-recognized green building certification system. In New Zealand we have the NZ Green Building Council which runs the Green Star certification system for commercial buildings. This provides a similarly recognised way assessing and certifying buildings in the New Zealand context.

Certainly in my experience as a laboratory architect I would have to agree that the earlier all aspects of the laboratory design are incorporated into the brief the better the end result will be. This includes the need to carry out a full review of current and future needs, an analysis of space utilisation, commonality review where the ability to share resources is looked at, as well as consideration of the environmental conditions required.

The more information you have about your actual needs versus your nice to haves the more efficient the final result will be. Not only for the size and operation of the building but also for the science and functions carried out within this environment.

In the past we have conducted these reviews for our client as a part of the briefing process. Especially the need to establish the size, relationships and environmental conditions the spaces need. Equally we have worked with a number of clients who have the staff and expertise to carry out these sorts of reviews and analysis themselves as a part of their planning process.

Inside the Coastal Ecology Lab

Inside the Coastal Ecology Lab

However, what has become very apparent is that you need the right people with the right experience (or ability) to do this pre-work. Whether it be outside consultants or in-house staff, the biggest impediment to the success of a project has been the quality of the data that is used to inform the brief, that ultimately flows on into the facility design. Add into this a layer of energy and building efficiency and the importance of pre-design and preliminary design is increased.

As a result we have developed a very robust and comprehensive briefing process, which includes questionnaire sheets to ensure as much information as possible is extracted out of the client’s head and onto paper, so it can inform the design.

As I sit here watching the snow fall in central Wellington, one example of this comes to mind, which included thinking a bit outside the box,. The Coastal Ecology Laboratory for Victoria University, sits on the south coast, overlooking Cook Strait. Here they run numerous experiments using sea water inside the facility, which is pumped straight out of the sea across the road. This gave us the opportunity to install the first commercial sea water heat recovery system. Recycled seawater from the laboratory experiments is circulated through the heat pump to recover energy, which is then used in radiators throughout the building. Combined with other smart design features, the energy consumption is reduced by over a third.

Lab overlooking Cook Strait

Lab overlooking Cook Strait

At least with this system, it won’t shut down in extreme cold like heat pump air conditioning systems have a habit of doing.

The best advice is to ensure that you allocate enough resources to get the information needed to make informed decisions on the brief and design of the facility. It is a hang of a lot cheaper to incorporate features or make changes in the design process than it is when the building is half completed, or even worse, having to put up with issues that create operational problems for the lifetime of the building.

More Power, Less Acceleration Ken Collins Mar 16

Time Ball Station Aerial_600x400

Lyttleton's Time Ball Station from the Stuff web site

Just a quick update today, following on from the theme of the last post, and the horror of the devastation Japan is now experiencing.

With the NZ government announcing a Royal Commission of Enquiry into the building collapses in Christchurch, it has been interesting to observe people’s perceptions, from politicians all the way down (or should that be up?).

The disconnect is partly in trying to understand why there was so much damage in Christchurch for a relatively small 6.3 magnitude quake, as opposed to the massive 9.0 quake seen in Japan.

So the follow on from my last post on ’Buildings are not Designed to be Race Cars’ where I talked about Peak Ground Acceleration (PGA), I thought it would be interesting to make some comparisons.

The Geonet map from the February quake is here and shows central Christchurch had a PGA of between 0.6g and 0.8g with up to 1.88g in the eastern suburbs and an incredible 2.2g at the epicentre.

Japan Intensity Shaking Map from USGS web site

Japan Intensity Shaking Map from USGS web site

The PGA maps from the U.S. Geological Survey show that in Sendai (about 130km from the epicentre), the PGA was 0.21g, with surrounding areas experiencing between 0.35g and 0.65g. In Tokyo the PGA was 0.17g. Have a look at the maps here and you can mouse over recording points to see the PGA expressed as a percentage of g.
eg 100% = 1g, 20% = 0.2g.

Even at these levels of acceleration it would appear that some buildings in Japan suffered structural damage as a result of the earthquake rather than the Tsunami.

So here’s the kicker. At the earlier reported magnitude of 8.9 in Japan (it has now been updated to M9.0) the energy released was 8000 times greater than in Christchurch, but the Japanese mainland experienced a significantly lower PGA than Christchurch did.

The Christchurch experience was reported as a short sharp jolt that was extremely violent. The Japan experience has been reported as a very long sway that just continued to build and build in intensity.

Location, proximity, soil types, rupture dynamics and many other factors mean that how each eathquake is expressed (and felt) at the surface is different.

And now back to the design of buildings. How do you best account of these huge differences so that you can structurally design buildings with some certainty? Can a building be made to reliably resist a PGA of say 1.5g (when a Formula 1 car accelerates at 1.4g)? Can older buildings be retrofitted to even remotely approach this? Assuming not, what level is an acceptable level to get older buildings up to? Will we ever experience that sort of PGA again in NZ? So is it worth designing buildings to resist that?

Engineers can now point to real life examples to answer many of those questions and scientists have more data to analyse than they have ever had before .

There are many, many newer buildings in Christchurch that did survive remarkably intact, despite the PGA they experienced (apparently) exceeding their design load state. For instance, a new-ish building around the corner from the CTV building hasn’t even a broken pane of glass.

Again, I must stress that I am not a structural engineer, and these are my thoughts as an Architect. But these are all questions that we have been discussing in our office, with no clear answer. The Department of Building and Housing and the Royal Commission will certainly have their work cut out trying to make sense of it all. And lets hope that sense does prevail.

Buildings are not Designed to be Race Cars Ken Collins Mar 04

Christchurch Earthquake trace from

Christchurch Earthquake trace from

Amongst the tragedy and ruin of last weeks Christchurch earthquake it hasn’t taken long for the blame game to emerge. Watching and reading the popular media over the last few days it is obvious that they want someone to publically flog for the terrible collapse of the PCG building and the CTV building.

Fortunately the Department of Building and Housing have already stated that their investigation will focus on finding the facts and it does not address areas of blame. That is the logical first step. If after that there are things that can be learnt, then that is good. If it is found someone was negligent than that needs to be addressed separately, in the fullness of time. However, I don’t believe that trying to find a blame hound now is very constructive.

I am not a Structural Engineer, so this is my opinion as an Architect, and below are a few relevant points as I see them, in order to provide some context.

Apart from the historic buildings, the two collapsed buildings were reported in the Dominion Post as being built in the 60s and 70s, and it is reasonable to believe that they were built to the relevant structural standards of the time.

In work our practice has done in the past few years, it has been identified that the structural standards for earthquake resistance has increased 3 fold since that time.

The structural design and design loadings standard NZS 4203 was first dated 1976, then 1984 and 1992. In the last few years AS/NZS 1170 has replaced 4203 and the structural requirements for earthquake resistance jumped up quite significantly in some aspects.

I know of one significant building in the Wellington CBD that was extensively retrofitted in the early 1980s to resist earthquake loads, at a cost of many millions of dollars at that time. Despite that work, the building has recently been assessed as being earthquake prone against current standards. The current owners are now spending much more to retrofit more extensive bracing and strengthening measures.

The often quoted ’Magnitude’ scale for earthquakes — as in magnitude 7.1 — gives a measure of the energy released by an earthquake, which is helpful in determining comparative size. However it does not indicate the shaking force or how violent a given quake is.

The general media appear to be stumped as to why a magnitude 6.3 quake produced so much more damage than a 7.1 quake. Apart from depth and location, the reason is ground acceleration.

We discovered the difference when we were designing a laboratory that you really don’t want to fall down when the big one hits. During the design phase the client asked what magnitude quake the building would resist. Oh, if only it were that easy sir, replies the structural engineer.

What the structural standards refer to is ground acceleration. How fast the ground moves determines how strong the building on top needs to be to either move with the ground or to resist falling over until the ground comes back to about the same location.

However, if the ground is not just going side to side but up and down as well, then it becomes increasingly harder to hold the big heavy hollow object together.

Referring to data from the web site it shows that during the September 4 quake the ground acceleration in Christchurch central was between 0.1g and 0.32g. g being the force of gravity.

In the February 22 quake the force was between 0.57 and 0.80g in the CBD area.

The highest shaking was recorded at Heathcote Valley Primary School at 2.2g, with readings of 1.88g at Pages Road Pumping Station and 1.07g at Hulverstone Drive Pumping Station!!.

For some perspective on this, a Formula One car accelerates at about 1.4g. Buildings don’t.

Those are huge forces in any language. Just in the CBD alone the ground acceleration was 2 to 3 times as great for a quake that was almost 1 order of magnitude less.

The map for the September quake is here and the February quake is here.

Early indications are that the Port Hills are now 400mm higher than before, meaning that the reverse faulting mechanism thrust the ground up some distance.

In short, as we wait to see what the technical reasons are for the two major collapses, the fact of the matter is that there is a point where we can not resist all of the forces of nature.

It is possible that the structural loading standards will be modified yet again as a result of the reviews to come. However you can only build to what is anticipated to be the likely expected ground acceleration. Before our places of shelter become — to quote Edmund Blackadder ’a small windowless building’.

How Building Standards Have Changed Ken Collins Oct 04


With the recent events in Canterbury and Invercargill it looks like the building standards in NZ will again come under close scrutiny.

The suitability of our standards is a valid question and response, especially when our knowledge has recently been increased by the Earthquake and the collapse of the Invercargill sports stadium roof.

The first design standards for earthquake loadings on buildings were introduced in 1935 following the 1931 Napier earthquake. Since then, significant advances in the required design standards have been made with major changes incorporated in 1965 and 1976.

Even more recently the structural design standard NZS 4203:1992 was replaced with NZS 1170 in 2002, with part 3 and part 5 added in 2003 and 2004. However NZS1170 has only been mandatory in the last couple of years, with engineers able to use either 4203 or 1170 up until then.

Certainly the requirements in 1170 are far greater than 4203 and this has increased building costs by quite a bit as additional structure is required to resist wind, snow and earthquake loads.

Previous Lake Angelus Hut

Previous Lake Angelus Hut

As a practical example of the changes over the years, we were involved in refurbishing a reinforced concrete church built 50 years ago. The Structural Engineer doing the assessment was impressed that the building had been well overdesigned for when it was built.  Possibly at 1.5 to 2 times the earthquake strength required for its day.

Despite this the building still only came up to 65% of the current requirements in NZS 1170. However this building is still not deemed to be an earthquake risk, which is set 33% or less of the current standards.

On this basis, the structure required to resist earthquake loads has increased about 4 fold in the last 50 years.

Angelus Hut under snow

Angelus Hut under snow

Similarly when you look at the requirements for wind and snow loads, some clients have been surprised at what is now being required. We have designed tramping huts to replace some old ones built in the 50s and 60s. Some of these are in high alpine areas with significant loads being imposed. (See the photo below, where there is only 500mm of the roof ridge sticking above the snow, the rest of the hut is completely under snow).

When you look at the existing hut, which has survived storms and the harsh environment for 50 odd years and is still sound, and you see how little timber was used to hold these things together, you wonder how the old buildings survived. Especially compared to the new buildings where there is significant bracing, and timber structure required.

Unfortunately the Stadium Southland failure is a stark reminder of what can happen. I suspect that it will be some time before the full details of what went wrong will be known, and it will be a combination of factors the contributed to the failure.

With snow it is a combination of factors as to how the load gets imposed. Roof shape and slope, the shape or geometry of the structure, the strength of the connections, the types of materials used, the amount of snow, and how long it is there for, all contribute to how well the building structure as a whole performs. It may be that the building was designed to the previous standard, which was deemed suitable 5 years ago, but as we have seen, what was acceptable years ago is now no longer.

New Angelus Hut

New Angelus Hut

Thanks to nature, we now have some real live examples to test the theory and assumptions against. Our building standards will continue to evolve and change as our knowledge improves, and as we have more ’learning experiences’. However it does occur to me that no matter what we do we can never be 100% future proofed against nature.

You can build to resist the shaking induced by the ground acceleration of an earthquake, but you can’t build to resist the ground moving by even 300mm. As we have seen in Canterbury, if the ground doesn’t just shake but permanently shifts up, down, or sideways, it will tear your building apart.

Fit for Purpose? Ken Collins Aug 05

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This recent article on The Herald web site highlights how careful we all need to be when trying to contain things in a secure laboratory environment. While I don’t know the specific details of this particular facility or the event that was investigated, it does highlight that the success of any laboratory is the interaction between the buildings features and the procedures used to operate it.

All scientific buildings need to be built toAM120 low res minimum standards, and depending on the use of the building, those standards demand different features to be incorporated. However, to ensure that the building provides the environment needed, the management regime needs to be carefully considered to ensure the correct features are provided.

A couple of illustrations to demonstrate this.

The standard says all surfaces must be able to be wiped down with disinfectant. If the operating procedure calls for the use of a typically used, every day product then the walls, floors and other surfaces can be made of relatively standard materials, so long as they are smooth and water resistant. If on the other hand the operating procedure calls for the use of a strong alkaline solution at very high temperature, then the building and the fittings need to be constructed of entirely different materials.

As another example, the standard says the lab needs to be fumigated. If the management system determines that you are going to close off that area and clear out all people, then the building features are relatively straight forward. If on the other hand you want to be able to keep staff working in the adjacent room, with a pressure differential between the rooms, then the building structure and the mechanical plant required is significantly different.

Although both systems are suitable for the same science being done, one is significantly more inconvenient and time consuming than the other. One is also cheaper than the other.

You can then see the potential problems where you change the management system later on, and the building environment may not cope too well.

It is equally true in the reverse, where a time consuming or limiting operating procedure could be significantly improved by changing some of the building features, so as to allow greater ease of use.

It is human nature to take short cuts where an operating procedure is overly complicated or an impediment to doing their work.

Therefore a comfortable balance needs to be struck of features, environment and usability. Careful consideration of (what usually boils down to) cost vs benefit needs to be taken during the design stage of any new or refurbished facility. It also needs just as much consideration when changing the use of an existing facility. Especially when you consider the total life cycle costs and operational costs.

For any scientific facility to be successful, the building needs to have the right features, that match how it is going to be used. Then these two together need to be suitable so that the users are able to (and want to) do their science (work) in that way.

Leaky Buildings — Part 2 — What we now know Ken Collins Jun 08

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Following on from my blog on Leaky Buildings – Part 1 -and how we got to where we are, this blog covers some of the science and research that has gone into the building industry as aponding water lounge roof result.

At this stage I must point out that there are other people with specialist areas of knowledge and research, in what is now quite a wide topic.  So, as blogs tend to be, this is more of an overview from my experience, rather than a detailed technical paper.

With all buildings that have ’leaking’ issues, the problem is that water gets into an area it shouldn’t be (most commonly the structural timber frame), the water stays there because it can’t drain or evaporate away. When the timber remains wet (typically above 30% moisture) and relatively warm, these conditions allow fungi to grow, which rots the timber.

The ways that water gets into a building falls into 4 broad categories, with many iterations in between where a combination of these forces are at work.

Gravity: generally a hole that water drips into, or where water is flowing down a cladding (or a flashing) that doesn’t adequately direct the water away, out of the building fabric.

Capillary Action: where water in the ground is soaked up by building materials (including DSC01305concrete) and transferred along to structural elements over time. This is commonly what is referred to as rising damp. It also happens where water is allowed to pond and hydroscopic materials are soaking in it (or close enough for rain splash to soak the material).

Condensation: the interior of your house is full of water vapour. From cooking, showering, laundering, un-vented gas heaters, and your own hot breath. If this vapour isn’t extracted or vented out of the house then it can condense on cold surfaces. Such as you see on your windows in winter. This also can happen inside your wall if the conditions are right.

Air Pressure: or more specifically a pressure differential. When it is windy there is a higher air pressure on the outside of the building than the inside. This in effect sucks air through any holes, cracks or openings. If it is raining then the water is taken in along with the air flow.

If you think about all the things that can happen in and around our buildings, the number of ways water can get into our buildings are too numerous to mention. It also follows that just because water has got into a building doesn’t mean it is a ’leaky building’ as such, which commonly implies a cladding failure.

The action (or in-action) of owners has always been an issue. All buildings require regular maintenance, and sometimes a bit of good old fashioned TLC is all that is needed to keep the building water tight. A recent article on the Beehive roof leaking is a perfect example of this.

Another classic is for gardens to be built up around the house. If the sub-floor vents are covered this significantly reduces the sub-floor ventilation and the water coming out of the ground under your floor isn’t removed, allowing sub-floor framing to remain wet. If the bottom of the cladding is buried in the soil (or even too close to the ground) then this will allow water to easily wick up into the framing.

There are a number of variables and reasons for condensation to form inside a wall cavity. Relative humidity, air pressures, vapour pressures, and temperature differentials all contribute to where the Dew Point is. This means that in certain circumstances water vapour could be condensing on the timber framing, inside the insulation, on the back of the cladding, or even on the building paper. This is a known cause of some so-called leak problems and rotten timbers.

When people talk about ’Leaky Buildings’ the most common image that comes to mind is of water getting into the timber framing, through a hole in the exterior cladding, and that timber remaining wet. In the early days of the current leaky buildings problem, existing brick veneer and cavity stucco designs were simply adapted to a wider range of claddings. It was recognised that if (when) water gets through a cladding, a cavity between the cladding and the building paper which is attached to the timber framing allows it to either evaporate or to drain away.

Further research has also shown that the reason for this is that cavity helps to equalise the Window-detailsair pressure behind the cladding, and the lack of air flow allows water to drop out and drain away. But of equal importance, it has shown just how effective a cavity is at allowing any moisture to dry out. BRANZ released initial results of it’s research in Build Magazine in June/July 2007.

They found that water dries 100 times faster from the back of the cladding than from inside timber framing, mainly due to how fast water diffuses through timber. When you add in that we are demanding higher levels of insulation and air tightness in our buildings, the ability for wall framing to dry out is further reduced. This unwanted water then tends to evaporate and condense repeatedly until it soaks into the wall materials or migrates inside the building.

The dilemma we now face is now how to allow for air movement and moisture drainage in a wall while still maintaining a high level of insulation. A cavity behind the cladding allows for ventilation and a drainage path, but it also decreases the insulation value of the wall. So more insulation is shoved in the wall, reducing the ability of the wall to breath even further.

The BRANZ research also highlighted what a significant part air pressure has to play in leaks. The Acceptable Solutions to the Building Code requires that all window and door frames be fully sealed to the structural timber frame to eliminate the air leakage path around these openings. Testing showed that even a small gap in the sealant had a big impact on air flow, and the water it carries. So the important thing is for the cavity behind the cladding to remain at an equal air pressure to the outside. In effect the cladding is now acting as a rain screen, rather than trying to achieve a waterproof membrane.

The truth is that we have ‘thought-built’ buildings. We always have had this, and it is even more so now. To build houses the way we do (in New Zealand) requires knowledge, skill and understanding. Construction clearly requires the designer, inspector, and builder to work from the neck up. They need to think as they draw, observe, and install the building components, like flashings, building paper and claddings. Thinking about where water will be coming from, and where it’s going to go. Miss something and the whole stack of cards can come down.

This is even more so with the rise of ’cladding systems’ where the one manufacturer provides all of the flashings, fixings, and finishings. Even good old fashioned things like weatherboards and bricks are starting to fall into this category. You now need detailed knowledge of how to install a particular system to make it work. Specialist installers, trained by the manufacturers are growing in number. On a recent project there was even a company who specialised in installing just the sealant between the windows and the timber framing. Almost gone are the days of generic claddings where you could use what ever individual components you liked and the whole thing still worked.

This obviously isn’t the be all and end all of this problem. There is a lot more to be learnt about how our buildings work in our environment. We are already seeing that some supposedly remediated buildings, aren’t, and they are leaking again. The story still has some way to go — unfortunately.

Leaky Buildings — Part 1 — How did we get here. Ken Collins May 20


With the government announcing it’s IMG_7549-web(our) package to help solve the leaky homes crisis this week, it has brought the spotlight back onto what is now a highly emotive subject. While the emphasis is rightly on getting peoples homes safe and fit to live in, it should be remembered that the leaky buildings problem is wider spread than just domestic buildings. Recent reports have shown that it includes schools, commercial and community buildings.

The politics of it is complex and controversial with blame-storming rampant. The reality is that there are so many aspects to obtaining a completed building, from design to move in, that you can’t just point your finger a one person or organisation.  Additionally the physical causes, effects and remedies are only now becoming well known and well understood.

So how did we get here?  In effect it was a combination of a number of issues, coming together all at once.

Ever since humans have built structures and shelters on this land, they have leaked, for one reason or another. In the early 20th Century buildings leaked, however the timber that was used was good strong native timber, which could withstand being wet and then drying out again. The gaps and construction technologies of the day meant that there was airflow through and inside the building structure, which allowed it to dry out. These days everything is sealed up like a chilly bin and any water that does get inside the structure can’t get out again. The timber stays wet, fungus grows and timber rots.

The use of un-treated timber was approved when the kiln drying of timber had become commercially available. Up until then all timber was naturally air dried and would normally be stood up as framing while it was still well above 20% moisture. It would then dry out as the house was completed.  The testing of the day showed that ‘dry’ timber (at it’s moisture equilibrium of about 12-15%) didn’t need treating, assuming it stayed dry. It also meant significantly less energy, chemicals and heavy metals were used in the building industry.

However history has proved that some of this timber didn’t stay dry.Imported-Photos-00026-web

What people also didn’t realise was that the old Boric treatment applied to timber being used internally (to stop borer attack) actually provided some protection against fungal attack when it did get wet.

At the same time the design fashion of the day changed to the use of parapets and low pitch roofs, monolithic plaster wall systems, and the mixing of different cladding materials on the one building.

New cladding materials and cladding systems relied to heavily on thin top coats where the base materials are not inherently water proof, or where jointing systems have proven over time to be ineffective or to be difficult to install and maintain.

The use of sealants to provide flashing and waterproofing barriers increased exponentially, at the expense of mechanical flashing systems. People relied on these chemicals to stop water getting into all sorts of little (an not so little) openings. So while sealants work very well when they are installed properly, they do need maintenance and replacement, especially where they are exposed to UV light.  However all to often they weren’t used or applied in ideal conditions and they failed prematurely as a result.

Added to this there was a lack of continuity across all the disciplines in the building industry, where traditional roles and responsibilities were fragmented.

Despite all of this, it must be pointed out that at the time the majority of people involved in the building industry thought they were doing the right things. Products were researched and tested, assessments and decisions made on the information available. Yes there were (and still are) some dodgy developers, builders and designers out there, but in no way can they account for all of the problems we are now observing.

One of the biggest realisations has been that despite the knowledge obtained from testing IMG_5557-webconstruction and cladding systems to assess their suitability for New Zealand conditions, the true test has been their actual performance in the real world over 5, 10, 20, 40 years. It is particularly hard to assess likely in-use performance by doing accelerated weathering experiments and the like. Often people relied on overseas testing and research, which wasn’t always totally applicable to NZ conditions.

The result is that in the last 10 years many methods that were thought to be ok, have proven to not be. Manufacturers have changed their installation, fixing and jointing instructions. A number of products that were tested as being suitable for NZ buildings have been withdrawn after they were found to fail. This includes products that were assessed by the Building Research Association of New Zealand (BRANZ) and given a BRANZ Appraisal Certificate, only for that certificate to be withdrawn later when problems arose.

What was thought to be best practise 10 years ago, now isn’t and so things have changed, and will continue to do so.

The fact is that you can never know with 100% accuracy how a material or a system will perform until it has actually been in use, in the environment, for a period of time. There are so many variables of, exposure, wind loads, quality of workmanship, movement inherent to timber framed buildings, not to mention maintenance (or the lack of it). After all, how many people wash their houses down every six months as is recommended by paint and roofing manufacturers.

Lessons have been learnt and things are now done differently. Will they prove to be successful over the medium to long term, the industry won’t know until we get there.

In the second part of this blog, I will look at some of the science behind the issues and what is currently thought to be the best solutions.

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