science

Leaky homes crisis

Leaky homes crisis is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Leaky homes crisis rather than just read about it. In short: 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.

Key takeaways

Leaky homes crisis belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Leaky homes crisis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Leaky homes crisis from memory before moving on to harder problems.

Reference excerpt

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.

Factors 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. 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. Court cases have generally assigned around one third of the financial responsibility to local authorities. A 2013 Supreme Court case involving the Auckland City Council extended the liability of local bodies.

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

Cladding systems 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. 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 (radiata pine) timber for wall framing. As this timber has little natural resistance to rot when wet, damage occurs more quickly. 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.

Drawings 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. Council staff carrying out building inspections had neither the required construction expertise to ensure weathertightness nor the intuition to look for it.

Juvenile sapwood A likely major contributing factor was the exhaustion of New Zealand's "First Rotation" (50-60 year old) radiata pine crop in the late 1980s, and the change to using short rotation 25-30 year old radiata pine at the same time. 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 utilise the wood would have to be developed. 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. 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.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Leaky homes crisis

Start with the simplest possible case. Write down what Leaky homes crisis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Leaky homes crisis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Leaky homes crisis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Leaky homes crisis

In research: Leaky homes crisis appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Leaky homes crisis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Leaky homes crisis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Construction accidents, Economy of New Zealand, Houses in New Zealand, so understanding it makes those chapters shorter.
In everyday life: Look for Leaky homes crisis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Leaky homes crisis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Leaky homes crisis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Leaky homes crisis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Leaky homes crisis in simple terms?

Why does Leaky homes crisis matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Leaky homes crisis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Leaky homes crisis.