Leaky homes crisis

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The leaky homes crisis is an ongoing construction and legal crisis in New Zealand concerning timber-framed homes built from 1988 to 2004 that were not fully weather-tight. The problems often include the decay of timber framing which, in extreme cases, have made buildings structurally unsound. Some buildings have become unhealthy to live in due to moulds and spores developing within the damp timber framing. The repairs and replacement costs that may have been avoided were estimated in 2009 to be approximately NZ$11.3 billion.[1]


The Building Act 1991, which became law in 1993, changed building controls from a prescriptive system to a more self-regulated regime. In addition, the Government dropped the apprentice training system for builders and the related building trades. Some developers and builders knowingly or carelessly constructed buildings with numerous faults and short-cuts. An architectural design trend towards Mediterranean-style houses with complex roofs, plastered exterior walls, internal decks and small or no eaves also factored in.[2]

Some local authorities were later found to have issued Building Consents based on insufficient documentation, failed to carry out inspection of the work during construction, and issued code compliance certificates for buildings which were later found to have leaking problems. Consequently some councils now share significant financial responsibilities with the builders (which in many cases have closed or otherwise removed themselves from liability) and the owners.[3] Court cases have generally assigned around one third of the financial responsibility to local authorities.[3] A 2013 Supreme Court case involving the Auckland City Council extended the liability of local bodies.[4]


There are many reasons that some buildings from the late 1980s were leaky.

Cladding systems[edit]

A major one was the increase in the use of cladding systems such as fibre cement sheet (generic name Fibrolite in New Zealand) and EIPS (Externally Insulated Plaster System) that relied on a paint finish as the primary defence against water ingress. This system is very similar to Exterior insulation finishing system (or EIFS). Such cladding systems typically allowed for little construction or thermal movement so that fine cracks that appeared insignificant, and would have been relatively insignificant in traditional claddings such as weatherboard, allowed continuous ingress of moisture into the framing.[5] These causes, combined with the reduced air movement through the prevalence of sheet cladding or sheet insulating materials for the monolithic look cladding, resulted in very damp conditions which are ideal for rot. A further exacerbating factor that resulted in more significant damage from the leaks, was the change to the New Zealand Standard for Timber Treatment in 1995, allowing the use of untreated Pinus radiata timber for wall framing.[6] As this timber has little natural resistance to rot when wet, damage occurs more quickly.[7]

In many cases claddings were not used within their specifications or not installed correctly. Many buildings built in the "Mediterranean" style used these types of cladding and had features such as recessed windows, flat roofs, minimal eaves, multiple storeys, complex roofs, solid balustrades, balconies and penetrations of the exterior cladding that increased the likelihood of water infiltrating the structure.[8]


Lack of detailed drawings for buildings was also a contributing factor. Some builders were unable to make a weathertight structure without proper guidance. This has partially been blamed on the breakdown of the apprenticeship system and unqualified builders in the marketplace.[9] Council staff carrying out building inspections had neither the required construction expertise to ensure weathertightness nor the intuition to look for it.[10]

Juvenile sapwood[edit]

A likely major contributing factor was the exhaustion of New Zealand's "First Rotation" (50-60 year old) Pinus radiata crop in the late 1980s, and the change to using short rotation 25-30 year old Pinus radiata at the same time. The "new crop" Radiata timber was found, in an "unpleasant surprise" to consist near entirely of juvenile sapwood, - a type of wood found in only limited quantities in traditional forestry timbers and classified as a type of "abnormal" or "atypical" wood.

Juvenile wood (aka apically influenced wood, aka core-wood) is present in all trees in small amounts near the center of the trunk, with the remainder of the wood comprising mature wood, and there being a spectrum in the change in cellular qualities outwards from the core from the most pronounced juvenile wood to normal mature wood. With age, the juvenile wood and mature wood is progressively converted to heartwood, stabilising it to a degree, so a tree can have juvenile sapwood, juvenile heartwood, mature sapwood and mature heartwood. Juvenile wood of both types is intrinsically inferior in all functional qualities to mature wood, but juvenile sapwood is the most problematic. A peculiar aspect of some conifers, which would appear to be a fire-adaption, is that when growing in post-fire environments or plantation forestry environments, production of juvenile wood is exaggerated and continues to a greater extent (in terms of number of annual growth rings outwards from the core) than in other woods. This is intrinsically linked to an unusually rapid rate of growth, such as seen in Radiata. New Zealand Radiata had always had more juvenile wood present than found in traditional forestry species. This had previously caused substantial problems in construction use in the 1950s and 1960s, but these had greatly diminished by the 1970s when Radiata's use became mainstream. This was because (a) the then advanced age of the First Rotation crop meant that much more of the first/butt log of each tree consisted of mature sapwood and juvenile heartwood; and (b) most of the first rotation had not been pruned, resulting in much of the worst of the central core of juvenile wood already being excluded by virtue of comprising a large "defect core" resulting from the unpruned branches. All of that changed at the end of the 1980s with the second-rotation, when for the first time since the 1950s and 1960s large quantities of juvenile sapwood started to hit the market. This was exacerbated by much of the mature wood being preferentially diverted to non-structural uses, in particular as clear-board timber, which was achieving a higher price. While in the 50's and 60's use of Radiata in construction was heavily promoted, by the 1960's its use was not recommended by the New Zealand Forest Research Institute or the New Zealand Institute of Forestry in their publications for any exterior residential construction, no matter how treated, due to its instability issues. Such use remained illegal under local building regulations throughout much of the Country as at 1960. Its use in framing remained (contrary to much currently published material) limited and near experimental in nature. Even by the early-mid 1970s a minority of New Zealand homes used Radiata in framing, and Radiata was typically more expensive to use than native woods. The 1970s was the time period which saw a changeover from native timbers being the mainstay of construction, and arguably it was not until the 1980s when having a combination of both Radiata framing and Radiata cladding became at all mainstream.

As warned by New Zealand's Forest Research Institute in 1992, some four years after significant quantities of the new crop started being used in construction but before the Leaky Homes crisis emerged, the new timber was problematic. Specifically, it was of lower strength, was prone to more distortion and surface checks, had low density, high spiral grain, and abnormal longitudinal shrinkage (and expansion). The latter quality had been blamed overseas for excessive movement in response to atmospheric conditions. Overseas studies of similar short-rotation produced juvenile sapwood had concluded it was so different from "normal" wood that it would be wise to treat it as though it were a completely different species. New methodologies to utilize the wood would have to be developed.[11]

Arguably the greatest issue was its significant longitudinal shrinkage and expansion (some seven times, on average, greater than any wood previously used in modern construction) and since shown to be sufficient to buckle structural members and associated cladding and roofing materials. Such movement was, and continues to be, of particular significance for rigid exterior claddings which during the Leaky Building crisis were found to have been suffering cracking, and the entry of water through capillary action, at an unprecedented rate.

Similar failures had been experienced in British Columbia from the early to mid-1980s when quantities of its "Second Growth" structural timbers began to enter the market, with those timbers too containing unprecedented amounts of juvenile sapwood. The United States had also in the early 1980s seen a small spate of significant construction failures due to the presence of juvenile sapwood in plantation grown Loblolly Pine that was entering the market, which led to much of the early research on the topic.

A crash research-project by the New Zealand Forest Research Institute to, amongst other objectives, attempt to identify how the new crop Radiata could safely be used in construction took place between 1995 and 1998.[12] That project gave rise to many of the innovations and regulatory measures later implemented to attempt to allow for safe construction using juvenile sapwood including, notably, the rise of LVL and other laminated structural products.

However intrinsic, and to date intractable, problems remain. The cellular structure of the wood is so non-durable and unstable (containing cell walls of completely distinct chemical and physical composition compared to normal wood)that even boron treated Radiata has exceedingly low durability, - indeed indistinguishable from untreated Radiata in graveyard testing. The sheer instability of modern Radiata means modern homes rely predominantly upon extensive flashings and moisture barriers to protect structural elements. The added complexity, cost, and often experimental nature of these systems renders homebuilding and maintenance a far more challenging exercise than previously the case. Such moisture barriers by their very nature tend to trap humidity, and because boron treated Radiata sapwood framing (juvenile or not) remains vulnerable to mould (and indeed boron actively encourages the growth of some moulds) modern New Zealand homes tend to suffer persistent, atypical, mould problems.

Interbreeding with failed "improved" strains of Radiata produced in the 1970s has, since the 2000s, further reduced wood density by an average of approx 10%. Kiln drying, near ubiquitous since 1990, has recently, unexpectedly, been found to significantly increase permeability of Radiata by action upon resin ducts. Significantly New Zealand's exports of Radiata timber for structural use remains near nil, with the few trading partners who do allow use of New Zealand Radiata for construction tending to have express restrictions in place to attempt to exclude the worst of the juvenile wood.


The Building Act 1991 was replaced by the Building Act 2004, which introduced a licensing scheme for building designers, builders and related trades. Councils were required to be registered with a central authority and were to be subject to regular quality control procedure checks. Council building inspectors remain unlicensed.[13]

The Government dissolved the BIA (Building Industry Authority, the Government department which was responsible for the oversight and administration of the building sector) on 30 November 2004 and replaced it with DBH (Department of Building and Housing).[citation needed]

Some of the Acceptable Solutions to the Building Code were re-written, most notably E2/AS1 External Moisture which covers the detailing of roofs and walls was greatly expanded.[citation needed]

The Standard covering durability of timber framing was amended in late 2003 with the publication of NZS 3602: 2003 Timber and Wood-based Products for Use in Building. This revision required a return to the use of treated radiata framing in external walls.[citation needed]

The Overview Group on the Weathertightness of Buildings that was appointed by the Building Industry Authority ("the BIA") to investigate the causes of the leaky building crisis did receive several submissions (including from the New Zealand Institute of Forestry, but not apparently from the New Zealand Forest Research Institute) suggesting that the reduced rotation age of the then current Radiata Crop might be a causal factor in the leaky building crisis.

In its final 2002 report the Overview Group recommended to the BIA that research be conducted as to whether there were any "issues regarding the structural strength and durability with respect to the maturity of timber". The outcome of that recommendation is currently unknown, with the Ministry of Business, Innovation and Employment advising in July 2019 that it had been unable to locate any records at all relating to any research or consultation having been undertaken in response to the Overview Group's recommendation.

Short rotation juvenile sapwood continues to be used throughout home construction in New Zealand, as the same cell-wall abnormalities which render it problematic for construction purposes render it vastly cheaper to process for pulp, and the short rotation is eminently suitable for the production of cheap "wood" for non-structural manufacturing use. A return to 50-60 year crop rotations remains unlikely, as the 25 year crop rotation was only recommended and adopted in the late 1960s due to (a) the lack of profitability of the 50-60 year crop rotation in terms of producing structural timber, and (b) in recognition that even the 50-60 year rotation was incapable of producing structural timber of a quality which would have any material international demand. While concerns were raised regularly by the New Zealand Forest Research Institute in published studies from 1980 onwards as the adequacy of the likely qualities of the Second Rotation's short-rotation crop, the reality was that by 1988 there were insufficient other domestic timber resources (other than native trees, which required conservation) that could meet New Zealand's demand for structural timber.

While considerable research continues by the New Zealand Forest Research Institute into the divergent anatomical, physical and chemical properties of juvenile sapwood, and scientific papers on the topic are regularly published by it, since the Leaky Homes Crisis emerged there has been little if any further published mention by it (or any Government body) of any possibility of juvenile wood causing construction failures, let alone linking juvenile wood to the Leaky Homes Crisis. Most current Government and industry publications, in defiance of the contemporaneous historical records, present the Leaky Homes Crisis as being an anomaly, and present Radiata as having been the predominantly used construction timber in New Zealand since 1945 (some 25 years before its actual use became at all prevalent). Consequently, few of the public in New Zealand (or even in the construction industry) have any awareness that the Radiata used in house construction in New Zealand since the late 1980s has been substantially different, and worse, than prior Radiata or Australian Radiata. Nor do many appreciate that the Radiata in structural use prior to the late 1980s was regarded by the industry and Government as being not only an expensive failure but also as being of extremely low quality. Nor is there any general awareness of how extensive the changes that have had to be implemented have been (to the extent of having to reformulate glues and resins to work with the new wood) to allow modern houses constructed using juvenile sapwood to stand any reasonable chance of lasting even 50 years, or of how unusual our residential construction remains relative to international practice and performance criteria. Accordingly no legal responsibility, or even criticism has ever rebounded onto the industry, or Government in relation to the use of short rotation and/or juvenile sapwood.

Housing affected[edit]

Several thousands of homes throughout the country are still awaiting renovation, with a total cost that has been estimated by a Price Waterhouse Coopers report to the Government in 2008 as being around NZ$11.3 billion for a consensus estimate of 42,000 buildings.[14][15] Other building experts estimate the true cost at $23 billion for 89,000 buildings, and accused government of reducing the figure of affected buildings to 42,000 buildings because they were allegedly "unhappy" with the expert prediction.[16]

Other buildings[edit]

The majority of affected buildings are homes or apartments, but in 2011 the twenty-year-old Ronald McDonald House for children with cancer and their families at Wellington Hospital was demolished as leaky and replaced.[17]

Schools affected[edit]

The Minister of Education said in 2009 that at least 73 schools were affected,[18] and in 2011 that 157 schools still needed repairs, at an estimated cost of at least $1.5 billion[19] As of 2013 the Ministry of Education was taking action against architects and builders involved with 87 of the 309 schools which have "leakiness" problems.[20] One school in Wellington, Seatoun School, built at a cost of $5.3 million and opened in 2002 is costing $4.5 million to repair.[21]

Financial liabilities[edit]

As of mid-2009, plans for an up to NZ$6 billion bailout package shared between government and local authorities are in doubt because the amount could affect New Zealand's international credit rating.[22] In November 2009, the National government decided not to offer a more substantial sharing of costs, and it is now estimated that in most cases, around 64% would have to be borne by the owners, 26% by Councils, and only 10% by government funds, while also forcing homeowners to sign away their rights to sue for more.[23][24]

Prime Minister John Key noted that while claimants did not have to accept the settlement, legal costs for bringing suit could eat up any further money awarded to them.[25] Some claimants have taken negligence claims against company directors of construction companies, relying on the decision in Morton v Douglas Homes Ltd [1984] 2 NZLR 548. There have also been accusations that parts of the legal and inspection professions are profiting substantially from disputes around the cases, and that significant money was diverted into these channels rather than into fixing the buildings.[3] The government's position was assailed by mayors of affected Councils and by pundits, who noted that by paying only 10%, and then receiving 12.5% back in goods and services tax, the government was actually making money from the crisis.[24] Another report commissioned by North Shore City Council estimated a potential gain by government of up to $2 billion.[26] Further, National was also criticised that as an opposition party, they had constantly asked for the then Labour-led government to assist homeowners financially.[24]

The government has also imposed a 10-year limit (after construction) on claims, even though some building experts believe many cases will only become apparent during coming years, as building rot becomes advanced enough. They also warned that houses in drier parts of New Zealand were now starting to show problems, which had simply developed at a slower pace – and that despite Building Act reforms in 2004, there were still houses being built that leaked badly due to shoddy workmanship. Timber needs a sustained period of wetting to form mould and subsequently rot. In laymens terms, the timber has to be wet longer than it is dry. In drier areas of the country it is unlikely the timber will remain wet long enough to instigate mould formation.[16]

In February 2010, New Zealand's Building and Construction Minister Maurice Williamson, National, warned that the size of the issue, at least $11 billion, was so gianormous [sic] that even a government with budget surpluses would struggle.[27] He noted that: "...a Government who's [sic] running deficits - and has a forecast track of deficits for many years out - has to just sit there with its head in its hands, saying, 'Well, I just don't how to do this'." He also warned that it was necessary to come up with a solution so money could be spent on fixing houses, rather than paying lawyers, and that there was a risk of significant rates rises in the major centres like Auckland, Tauranga, Wellington and Christchurch, of a scale that would "make eyes water".[27]

In May 2010 the New Zealand Government launched the Financial Assistance Package (FAP) for leaky homes, which expired in 2016. Under the scheme, the home owner shared the agreed cost of repairing their home with the government and the local council, if the council approved the original work and was participating in the scheme. The government and the council each contributed 25% of the repair cost with the owner paying the remaining 50%. Despite the FAP offering to give the homeowners the certainty of financial contribution and to help get leaky homes fixed faster, by November 2012 only 12 victims had received final payouts under the government scheme.[28]

In 2009 it was estimated between 22,000 and 89,000 properties were affected, but the government's scheme would cover around 3,500 at the most.[29]

Rates impact[edit]

Councils and politicians have indicated that the crisis could increase rates bills. From mid-2011, council must take leaky home syndrome into account when re-valuing homes, even if the home has not leaked. This takes into account that such homes face widespread stigma and are harder to sell. The lower values meant some owners paid 5% to 20% less for their rates, but other ratepayers had to pay more to make up the difference.[30]

Effect on liable firms[edit]

The placing into liquidation of Mainzeal Construction and Property, New Zealand’s third largest construction company, in February 2013 was blamed on both a slowdown in commercial construction work and liability for several leaky apartment buildings in Auckland and Wellington where other parties had gone out of existence. [31][32]

Similarities to British Columbia[edit]

A similar problem arose in the early 1980s, some 10 years before New Zealand and for similar reasons[33] in the Canadian province of British Columbia. It is commonly known in Canada as the Leaky condo crisis and has been an ongoing issue that is estimated to have caused $4 billion in damage since the 1980s.[33][34]


  1. ^ "Leaky homes will cost $11.3b to fix - report". The New Zealand Herald. 22 December 2009. Retrieved 26 February 2012. CS1 maint: discouraged parameter (link)
  2. ^ Coursey, Michelle (8 May 2004). "Leaky looks deter buyers". The New Zealand Herald.
  3. ^ a b c Laxon, Andrew (19 September 2009). "Leaky homes throw up $6bn repair bill". The New Zealand Herald.
  4. ^ "Court gives hope to leaky home owners". Stuff/Fairfax. 1 March 2014.
  5. ^ "Archived copy". Archived from the original on 27 August 2012. Retrieved 8 September 2012. CS1 maint: discouraged parameter (link) CS1 maint: archived copy as title (link)
  6. ^ "Why homes leak : Background to the problem". Department of Building and Housing and Consumer NZ. Archived from the original on 18 December 2011. Retrieved 20 December 2011. CS1 maint: discouraged parameter (link)
  7. ^ "Builders Guide to Timber". BRANZ. Archived from the original on 19 February 2013. Retrieved 8 September 2012.
  8. ^ "Why homes leak – Background to the problem". ConsumerBuild. 25 March 2010. Archived from the original on 4 April 2010. Retrieved 25 March 2010.
  9. ^ "Crisis point". New Zealand Listener. 20–26 February 2010.
  10. ^ "Kevin Clarke:Govt can't escape leaky homes blame". The New Zealand Herald. 25 March 2010.
  11. ^ D J Cown (1992). "Corewood (Juvenile Wood) in Pinus Radiata - Should we be Concerned" (PDF). New Zealand Forest Research Institute.
  12. ^ NZJFor 47(3) 2002 - "Value Recovery Project (1995-98) - What Did we Learn" - D. Cown
  13. ^ "Failings of the Building Act 1991 – Were these a cause of the leaky building crisis? Breaking down the Building Act 2004: What does it really mean? « Legal Vision – Leaky Building Lawyers". Retrieved 9 December 2018.
  14. ^ Brian Rudman (18 September 2009). "Government must plug those leaks". The New Zealand Herald. Retrieved 7 October 2010. CS1 maint: discouraged parameter (link)
  15. ^ Leaky home obligations 'overlooked' by Catherine Harris in Sunday Star-Times 15 July 2012 p. A7
  16. ^ a b Laxon, Andrew (27 February 2010). "It's not if – it's when for our dripping time bombs". The New Zealand Herald. Retrieved 3 March 2010. CS1 maint: discouraged parameter (link)
  17. ^ Rankin, Janine (9 February 2011). "Ronald McDonald House to go". Manawatu Standard. Retrieved 14 October 2011. CS1 maint: discouraged parameter (link)
  18. ^ Gibson, Anne (18 September 2009). "Schools' leaky building toll soars". The New Zealand Herald. Retrieved 14 October 2011. CS1 maint: discouraged parameter (link)
  19. ^ Fisher, Amanda (28 January 2011). "Huge bill for leaky schools". The Dominion Post. Retrieved 14 October 2011. CS1 maint: discouraged parameter (link)
  20. ^ O'Callaghan, Jody (8 March 2013). "Legal action begins on leaky school repair bills". Stuff/Fairfax. Retrieved 14 March 2013. CS1 maint: discouraged parameter (link)
  21. ^ Mansford, Tennessee (22 September 2011). "Wellington school's $4.5 million leaky building bill". Stuff/Fairfax. Retrieved 14 March 2013. CS1 maint: discouraged parameter (link)
  22. ^ Laxon, Andrew (12 September 2009). "$6b leaky homes bill threat to NZ credit". The New Zealand Herald. Retrieved 14 October 2011. CS1 maint: discouraged parameter (link)
  23. ^ McCracken, Heather (8 November 2009). "Leaky homes' heartbreak". The New Zealand Herald. Retrieved 14 October 2011. CS1 maint: discouraged parameter (link)
  24. ^ a b c Rudman, Brian (9 December 2009). "State needs to plug leaks scandal". The New Zealand Herald. Retrieved 14 October 2011. CS1 maint: discouraged parameter (link)
  25. ^ McCracken, Heather (9 November 2009). "Leaky homes deal just one option - Key". The New Zealand Herald. NZPA. Retrieved 14 October 2011. CS1 maint: discouraged parameter (link)
  26. ^ Gibson, Anne (26 March 2010). "Leaky homes a disaster and a $2b tax windfall". The New Zealand Herald. Retrieved 26 July 2010. CS1 maint: discouraged parameter (link)
  27. ^ a b "Govt stumped as leaky home bill skyrockets". The New Zealand Herald. 27 February 2010. Retrieved 20 March 2010. CS1 maint: discouraged parameter (link)
  28. ^ Chisnall, Kim (7 November 2012). "More than 1000 waiting on leaky home repairs". 3 News NZ.
  29. ^ "Only 30 take up Govt's leaky homes package". 3 News NZ. 12 October 2012.
  30. ^ Morris, Bruce (2 July 2011). "Leak crisis will hit every pocket". The New Zealand Herald. Retrieved 1 July 2011. CS1 maint: discouraged parameter (link)
  31. ^ Donoghue etc, Tim (7 February 2013). "Mainzeal subcontractors blocked from building sites". Stuff. Retrieved 7 February 2013. CS1 maint: discouraged parameter (link)
  32. ^ Harris, Catherine (7 February 2013). "Mainzeal sale likely if liquidated – PM (Leaky buildings sink Mainzeal Property and Construction". Stuff. Retrieved 7 February 2013. CS1 maint: discouraged parameter (link)
  33. ^ a b "The Renewal of Trust in Residential Construction - Commission of Inquiry into the Quality of Condominium Construction in British Columbia". 26 April 2010.
  34. ^ Vancouver Condo Expert Gerry Fanaken, Georgia Straight, 22 May 2013. Retrieved 2013-11-22

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