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Topic # 204327 27-Sep-2016 14:42
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I came across a house that was built in circa 2002 - the cladding is plaster over polystyrene ...

 

What do you make of that? Sounds very non permanent to me! 25 year life span? Would it have been lined by building paper with a cavity before the layer of insulation?

 

Ok I think I found the answer - apparently this very type is the leaky building syndrome type.

 

Would (not that I'm considering it, just for my education) something circa 2000, plaster over hardiboard, building paper, insulation - but no cavity between building paper and insulation - that would be slightly less prone to weather tightness issues? (Of course depends on a multitude of other factors which all compound but just comparing the cladding system alone)





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  Reply # 1641309 27-Sep-2016 14:50
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Woop woop, leaky building 101!!

 

You should be able to see the lower cavity cap (with holes) at the bottom of the buiding

 

http://www.weathertight.org.nz/new-buildings/detail-solutions/wall-cladding-selection/eifs/

 

http://www.weathertight.org.nz/assets/Uploads/_resampled/SetWidth696-fig-27.jpg




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  Reply # 1641310 27-Sep-2016 14:55
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What about plaster cladding system post leaky house era ie post 2005?

 

Also what about something circa 2000, plaster over hardiboard, building paper, insulation - but no cavity between building paper and insulation - that would be slightly less prone to weather tightness issues? (Of course depends on a multitude of other factors which all compound but just comparing the cladding system alone)





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  Reply # 1641313 27-Sep-2016 15:12
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If built and maintained properly there is nothing wrong with plaster over poly or any other plaster cladding without a wall cavity.  Yes that is a style more associated with 'leaky home syndrome' particularly given the shoddy workmanship and lax standards in that era, but that does not automatically mean it will suffer that fate, to say otherwise is just scaremongering IMO.  Heck even brick homes can leak. As with any purchase get it checked out properly by a qualified professional.  

 

 





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  Reply # 1641314 27-Sep-2016 15:15
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joker97:

 

What about plaster cladding system post leaky house era ie post 2005?

 

Also what about something circa 2000, plaster over hardiboard, building paper, insulation - but no cavity between building paper and insulation - that would be slightly less prone to weather tightness issues? (Of course depends on a multitude of other factors which all compound but just comparing the cladding system alone)

 

You need some sort of cavity to allow for air movement and water exit from behind the cladding  ( the plaster can absorb lots of water if sealings fail) , I would have thought removing the cavity would make the chances of water being caught in the framing even worse...

 

This is compounded by the use of untreated kiln dried pine between 1996 and 2003-4 (it was tightened even more in 2011)


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  Reply # 1641315 27-Sep-2016 15:16
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scuwp:

 

If built and maintained properly there is nothing wrong with plaster over poly or any other plaster cladding without a wall cavity.  Yes that is a style more associated with 'leaky home syndrome' particularly given the shoddy workmanship and lax standards in that era, but that does not automatically mean it will suffer that fate, to say otherwise is just scaremongering IMO.  Heck even brick homes can leak. As with any purchase get it checked out properly by a qualified professional.  

 

 

 

 

 

 

It is more to do with the flashings around openings and parapets, as well as the joints between the sheets, that are the problem. The cavity drains any water that makes its way through. The thing is that many construction details today do rely on a cavity existing, so that it can drain any water that does make it though. It all comes down to detailing and construction of those junctions. But the fact is even today there are leaky building being built due to poor detailing of flashings etc.


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  Reply # 1641341 27-Sep-2016 16:20
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joker97:

I came across a house that was built in circa 2002 - the cladding is plaster over polystyrene ...

 

 

It's not automatically bad, I've seen buildings in northern Europe that are plastic mesh + plaster over thick polystyrene blocks. OTOH they're frozen solid at least six months of the year, so the conditions will be quite different to NZ.



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  Reply # 1641358 27-Sep-2016 16:54
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As far as I'm concerned, there's always another house. Just flabbergasted that you could use polystyrene and some blue tack for a cladding





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  Reply # 1641386 27-Sep-2016 17:20
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joker97:

 

As far as I'm concerned, there's always another house. Just flabbergasted that you could use polystyrene and some blue tack for a cladding

 

 

 

 

Polystyrene is used under concrete slabs. It is also used in sandwich panels in between a layers of OSB board, so it is used a lot.

 

With walls it's durability is based on the exterior plaster system. It is a a reasonably cheap contruction method, because it also has insulation qualities. 


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  Reply # 1641429 27-Sep-2016 19:15
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mattwnz:

 

scuwp:

 

If built and maintained properly there is nothing wrong with plaster over poly or any other plaster cladding without a wall cavity.  Yes that is a style more associated with 'leaky home syndrome' particularly given the shoddy workmanship and lax standards in that era, but that does not automatically mean it will suffer that fate, to say otherwise is just scaremongering IMO.  Heck even brick homes can leak. As with any purchase get it checked out properly by a qualified professional.  

 

 

 

 

 

 

It is more to do with the flashings around openings and parapets, as well as the joints between the sheets, that are the problem. The cavity drains any water that makes its way through. The thing is that many construction details today do rely on a cavity existing, so that it can drain any water that does make it though. It all comes down to detailing and construction of those junctions. But the fact is even today there are leaky building being built due to poor detailing of flashings etc.

 

 

 

 

The chance now of getting poor flashing detail design through building consent is about 0%.  There's a possibility poor workmanship might not be picked up in a council building inspection, but the council inspectors are all over it like flies on s*^&, so the chances should be very low.  

 

I don't agree that post leaky buildings design "relies" on the presence of a cavity at all.  That (the cavity) is "braces" in a "belt and braces" approach - the "belt" - preventing water ingress through the cladding and around penetrations - is far more stringently controlled than it was during the leaky homes era.  For example - there's no way you'd get uncapped/unflashed parapets or window jambs sealed to cladding with RTV approved.  There's every chance that they'll insist on head flashings over windows etc, even when the top of the window is 50mm under eaves overhanging 600mm.

 

I'd be very wary of any home built with any materials during the leaky homes era - they might be okay, but you're going to need more than a superficial inspection and internet forum wisdom to be sure.

 

 

 

 




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  Reply # 1642546 29-Sep-2016 12:33
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Would a brick cladding built in the "leaky building era" be of the same standard as a brick cladding of the current era? Ie not looking at whether the flashings were done right, but things you can't see ie having building paper, and a cavity between the brick and the timber frame? Also when did treated timber become mandatory?





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  Reply # 1642644 29-Sep-2016 14:36
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1995 was when untreated pine timber was first allowed to be used for framing, through to about 2003.  Be careful with that "2003", as there will be homes with post-2003 completion date that were built earlier.

 

Personally I'd avoid buying any house in NZ built between those years, regardless of design, cladding type etc.  Leaky homes crisis had many causes - terrible workmanship being a main one, along with design, quality of inspection, everything.  It wasn't all about materials - it was about how those materials were used.

 

You could check if there's building paper by removing an electrical switch and flush-box behind, or other fitting on the inside of an external wall and take a look (don't electrocute yourself).  You should be able to see (by colour) if the timber stud the side of the flush box is screwed to is H3 treated. 

 

I believe that regs for spacing of tie-backs may have changed (for seismic performance reasons) since the '90s, but again because of crappy workmanship and lack of supervision, you could find things such as that they only bothered to put a few tiebacks in visible places for the inspector to see, but "forgot" about the rest when nobody was looking. Slab on grade foundations that were supposed to have steel reinforcing in them but didn't as they carted it away in the middle of the night and sold it to the next mug, then carted it away and sold it again, all kinds of appalling deliberate "cheats" that they got away with - not just stupid mistakes. 




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  Reply # 1642787 29-Sep-2016 16:53
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Thanks.

Just a question - I thought my 70s house also used untreated timber?




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  Reply # 1642921 29-Sep-2016 20:34
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joker97: Thanks.

Just a question - I thought my 70s house also used untreated timber?

 

 

 

Not if it it's pine, possibly if it's rimu - but that was probably not widely used any more- even by the mid '60s. 




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  Reply # 1643103 30-Sep-2016 08:39
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There are houses that have walls made of what looks like corrugated long run iron roof things ... What are those like?




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  Reply # 1643126 30-Sep-2016 09:31
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joker97: There are houses that have walls made of what looks like corrugated long run iron roof things ... What are those like?

 

There are plenty of 1900s villas in Wellington that have actual corrugated iron long run as walls, its all hardwood timber framing underneath, and have plenty of air "gaps" so water retention is not really a concern.... 


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