SUPERHOME DESIGN GUIDE
‍GLOSSARY

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A
ACH
Air changes per hour -- a measure of air leakage in the home, undertaken with a Blower Door Test. Superhome Certification criteria sets requirements for Base (less than 3 ACH), Better (less than 2 ACH) and Best (less than 1 ACH):
SUPERHOME CERTIFICATION GUIDE
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AIRTIGHTNESS
Airtight construction uses building materials to minimise heat loss and eliminate moisture and mould in the wall and roof assemblies. Airtight construction goes a long way towards creating a low energy, high performing healthy home. It is best practice to have the air control layer on the interior side of the ‘thermal envelope’ with the exterior layer being the weathertightness / windtightness layer (building wrap etc). In some types of construction for example SIPs, the air control layer may be part of the wall system, providing appropriate attention is given to all joints and junctions.

ALUMINIUM
A lightweight metal used in many products including window frames. It has a density about one-third that of steel, is non-toxic and non-magnetic, and has a high thermal conductivity. Because it conducts heat so well, aluminium window frames need to be thermally broken -- incorporating an insulating barrier (polyamide) separating the interior and exterior of the frame to improve energy efficiency and minimise condensation.

ART DECO
A distinctive international style of art and design from the 1920s and 30s, influencing architecture with designs including streamlined facades, geometric decorative elements, and graceful curved structures. The city of Napier was rebuilt after the 1931 Hawkes Bay earthquake and still features many beautiful Art Deco buildings.

AS
Acceptable Solution (NZ Building Code) -- specific construction details, materials and methods required for compliance with the Building Code:
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Alternative Solution (NZ Building Code) -- can also demonstrate how building work -- including materials, components or construction methods -- complies with the Building Code where a design differs from a conventional Acceptable Solution method:
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ASBESTOS
Fibrous fine silica minerals that were commonly used in the past for insulation and fire protection. Asbestos is resistant to heat, fire and chemicals and does not conduct electricity. It is a toxic hazardous substance and when inhaled causes cancer and other dangerous lung conditions. Before its health impacts were recognised in the 1970s, asbestos was included in many construction materials including insulation, plaster, flooring, roofing, exterior claddings and internal wall panels, adhesives, and decorative "popcorn" ceilings.In New Zealand asbestos was phased out with an initial ban on imports in 1984 and a total ban in 2016. However it is still present in many buildings built or renovated before 2000, and in soil and landfill:
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‍The first step in any renovation project is to have your building checked for any asbestos in the structure and materials. If you suspect asbestos, do not disturb it. Contact a qualified asbestos assessor before any renovation work. Removal and disposal of asbestos must be undertaken by a properly qualified professional.
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B
BASE / BETTER / BEST
The Superhome Movement criteria for certification establish three levels of efficiency and performance across ten dimensions (Design, Floors, Walls, Windows, Roof, Airtightness, Ventilation, Energy, Water, Materials & Waste). This gives flexibility and options for homeowners, designers, architects and builders to develop the best solutions for each project depending on your priorities, needs, site and budget:
SUPERHOME CERTIFICATION GUIDE

BEARER
A horizontal timber beam in the subfloor structure between the floor joists and the piles.A concept used to increase connectivity to the natural environment through the use of direct nature, indirect nature, and space and place conditions. Biophylic designed buildings incorporate things like natural lighting and ventilation, natural landscape features and other elements for creating a more productive and healthy built environment for people.

BIOPHILIC DESIGN
A concept used to increase connectivity to the natural environment through the use of direct nature, indirect nature, and space and place conditions. Biophylic designed buildings incorporate things like natural lighting and ventilation, natural landscape features and other elements for creating a more productive and healthy built environment for people.
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BITUMEN
A black viscous semi-liquid substance derived from crude oil, used in roading and in buildings for roofing, waterproofing, deck surfaces, underlays, sealants and damp-proof barriers.Health risks include respiratory problems from fumes, skin irritations and headaches. Bitumen can leach harmful substances, contaminating soil and water. Building materials containing bitumen must be disposed of safely – check your local council for hazardous waste disposal requirements.


BLOWER DOOR TESTING
A test to check the home for air leaks. This is important to assess the airtightness of the home and identify problem areas, gaps or cracks where air is escaping. A computer-controlled fan is installed in an exterior door frame to pressurise and depressurise the building, measuring the air changes per hour to evaluate the performance of the structure. Blower door testing is required for certification by Superhome Movement:
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Passive House and some Homestar certifications: (Green Bldg Council):
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BORER
Wood-boring beetles, common pests in NZ homes. Signs of borer infestation are small holes (flight holes or exit holes) across the timber surface, sometimes a dust deposit beneath, and soft crumbling wood beneath. Adult beetles lay eggs in cracks or old holes, and the larvae hatch and tunnel through the wood over several years, causing significant damage to the timber structure. Borer prefer softer sapwood timber and don't attack harder heartwood timber.In many older homes the borer insects will have long gone but the destruction to the timber remains -- affected wood will need replacing. If you have an active borer presence you can treat with a fumigator bomb or fluid.
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BORON PRESERVATIVE
A timber treatment to protect against insects and fungal decay commonly used for framing timber. It usually has a distinctive pink colour.


BUILDING CODE
The Building Code is established under the Building Act 2004 and sets out rules and requirements for the construction, alteration, demolition and maintenance of new and existing buildings in New Zealand. All building work must comply with the Building Code, even if it doesn't require a building consent:
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BUILDING CONTRACT
A legal requirement for any residential building work costing $30,000 or more (including GST). The Building Contract must be provided by a Licensed Building Practitioner along with a Disclosure Statement, setting out the prescribed requirements:
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BUILDING CONSENT
A legal requirement for building work and any significant renovations.The Building Consent is the formal approval from the local council to authorise your building or renovation project. Before commencing work you and/or your build team must check whether you need a consent, prepare the application and lodge it with the council. Most councils have guidance and support through this process.If you build or renovate without securing the necessary Building Consent, you may be subject to prosecution and fines. You may also be liable to a later purchaser of the home for work carried out without the required consents.Some recent policy changes are under way to allow construction of small stand-alone dwellings ("granny flats") without consent from early 2026:
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C
CAVITY WALL
A wall construction with a gap (cavity) between the inner and outer layers, providing space for drainage, ventilation and insulation. Common in modern NZ construction to prevent moisture transfer and improve thermal performance.
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CCA – COPPER CHROMIUM ARSENIC
Since 2011 most structural timbers must be treated to protect against insect attack and decay
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Treated timbers are likely protected with CCA (copper, chromium and arsenic) which is banned in most other countries but still used in NZ.Handling and cutting CCA-treated timber must be done with proper protective equipment – gloves, mask, goggles, long sleeves to cover skin -- and any sawdust or offcuts must be carefully disposed of to avoid soil contamination.
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CLT
Cross Laminated Timber. CLT is made from several layers of solid wood panels bonded with a structural adhesive at alternation right angles. It's ideal for large floor, roof, and wall elements, where mass timber can significantly reduce CO2 emissions compared to concrete and steel.
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CodeMark
A product certification system to demonstrate that a building product or method meets the requirements of the Building Code. A CodeMark certification must be accepted by councils for your Building Consent, provided the certificate is current and the product or method is used in accordance with details noted on the certificate.
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CONDENSATION
The moisture that collects on the inside of the windows in your home when there is a difference in temperature between the warmer interior and the colder exterior. Condensation and high moisture levels inside the home contribute to the growth of mould and mildew, and create significant health hazards especially for people with asthma or other respiratory problems. Condensation can also compromise the seals and frames of the window structures over time.

Proper ventilation systems, double or triple glazing, and maintaining consistent heating help prevent condensation.
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CREOSOTE
A black oily liquid derived from coal tar, used on timber (claddings, framing, posts, fencing) as a preservative and waterproofing. Creosote is known to cause cancer, organ damage, neurological damage, respiratory problems and other health impacts. It can release VOCs (volatile organic compounds) into the air, and can leach into soil and water, accumulating in the environment, and impacting fish and other wildlife.

Creosote was commonly used through the middle decades of the 20th century in NZ homes, but since 2003 it is not approved for public use. Offcuts and sawdust must not be burned and must be disposed of safely – check your local council for hazardous waste disposal requirements.

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D
DAMP PROOFING MEMBRANE
A barrier layer against moisture rising from the ground, to protect the structures of the home from deterioration and problems such as mould.
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DOUBLE GLAZING / TRIPLE GLAZING
Windows with two (double) or three (triple) panes of glass separated by air or gas-filled spaces. These provide superior insulation, noise reduction and condensation control compared to single glazing. Essential for achieving Superhome certification standards
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DWANGS
A horizontal bracing piece used between wall studs to give rigidity to the wall frames of a building. Dwangs / Noggings may be made of timber, steel or aluminium. Their use has lessened over the years. Dwangs should be narrower than the studs. Stopping the default practice of using framing-sized dwangs and minimising their use to only where necessary could benefit our environment and the standard of light timber-frame buildings.
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E
EAVES
The edges of the roof structure extending to provide shelter over the exterior walls of the home. The eaves are important for protection from weather and rain, and for shading to help avoid overheating especially on the northern and western sides of the building.
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EDAs
Eco Design Advisors. Help improve the comfort and health by providing independent advice on home performance. Working with clients to identify and maximise opportunities to do good (for people and planet) while performing well (for profit). Supporting sustainability disclosure, biodiversity and carbon offset strategies; corporate sustainability policies; land, water and GHG management; and philanthropic programs.
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EMBODIED CARBON
The total greenhouse gas emissions generated during the extraction, manufacture, transportation and installation of building materials. Choosing low embodied carbon materials (like timber over concrete or steel) significantly reduces a home's environmental impact. See also PARIS AGREEMENT.

EPDs
Environmental Product Declarations:
Independently verified statements of the life-cycle environmental impact of products and services, aligned to international standards:
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BRANZ Bulletin on EPD’s in the construction industry (updated in 2023):
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An EPD requires a comprehensive Life Cycle Assessment of the product, its manufacture, use or application through to eventual disposal. The standards are strict:
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F
FLASHINGS
A folded strip of metal used to create a weathertight join between roof sections and junctions, between walls and roofs, and around windows, doors, skylights, and chimneys.
Flashings are a requirement under the Building Code clauses B2 Durability and E2 External moisture.
Good flashings are essential to prevent water getting in to the building structure, and to ensure that any moisture that does get in can drain away safely:
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FOUNDATION WALLS
The foundation walls support the external walls of the home, and are usually constructed from reinforced concrete or concrete blocks: BRANZ advice:
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The formal technical requirements for foundations for timber-framed buildings are set out in NZS 3604:2011:
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G
GLU-LAM BEAMS
Glued laminated timber beams (GLT) are made from layers of timber bonded together with moisture-resistant adhesives so that all of the timber grain runs parallel. Glu-lam beams have low embodied carbon and a high strength to weight ratio allowing spans across wide areas.
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H
HARDBOARD
A high-density interior lining board made from pulped wood fibres compressed into thin sheets.
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HEAT PUMP
An efficient heating and cooling system that transfers heat rather than generating it. In winter, it extracts heat from outside air and transfers it indoors; in summer, it reverses to cool the home. Far more energy efficient than traditional electric heating.
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HESSIAN
A burlap or jute material, also known as SCRIM, used as a wall lining tacked to wooden planks before plaster or wallpaper was applied. A significant fire risk -- if you find hessian or scrim within the walls of an older home it should be removed and replaced with new plasterboard.
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HOMESTAR
A housing certification programme run by the NZ Green Building Council, rated on a scale from 6 to 10, assessing health, efficiency and sustainability of the home:
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HRVA – HEAT RECOVERY VENTILATION SYSTEM
A balanced ventilation system that extracts stale air and brings in fresh air while recovering heat from the outgoing air. Essential for maintaining air quality in airtight homes while minimising heat loss. Required for Superhome Better and Best certifications.

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I
(IEF) Indoor Environmental Quality
The quality of a building's environment in relation to the health and wellbeing of occupants, including air quality, thermal comfort, lighting, acoustics and moisture levels.
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INSULATION
The insulation requirements for homes in the different zones across NZ are covered under the Building Code clause H1 Energy efficiency, which were updated in 2023: BRANZ GUIDANCE 2025:
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There are many options for insulation materials available, including fibreglass (batts), polyester, mineral wool, natural wool, polystyrene, and loose-fill cellulose fibre. Other options include straw bales and SIPs (structural insulated panels):
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J
JOISTS
Horizontal timber beams in the subfloor structure between the floor and the bearers.
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LEAD
Lead is a dense heavy metal, commonly used in the past in a range of building materials including paint, nails, flashings and pipes. It is highly toxic, accumulating in bone and tissue, damaging the nervous system, kidneys and reproductive and cardiovascular systems, and causing neurological disorders and brain damage. Its impacts are particularly damaging to children. It contaminates the environment, accumulating and persisting in soils and water and working up the food chain to fish, birds and sea mammals.

In the 1970s most international jurisdictions banned lead in paints, and in 1979 lead-based house paint was banned in NZ. However lead paint can still be found in many older homes. Old lead paint must be removed using proper protective equipment, and safely disposed of – use a tarpaulin to ensure the paint scrapings do not contaminate the soil, and check with your local council for regulations for hazardous waste.


LEAKY HOMES
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.


LOW-E GLASS
Low-emissivity glass has an invisible metallic coating that reflects heat back into the room in winter while allowing sunlight to enter, and reflects heat away in summer. This improves energy efficiency and thermal comfort. Essential for high-performance windows in Superhome projects.


L
LVL
Laminated Veneer Lumber is a popular type of engineered wood product that uses multiple layers of thin wood assembled with adhesives. Typically used for headers, beams rim board, and edge-forming material. Made in a factor under controlled specifications, it's stronger, straighter and more uniform than typical milled lumber. It's less likely to warp, twist, bow or shrink. LVL beams, headers and columns are used in structural applications to carry heavy loads with minimum weight.

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M
MATCH LINING
Thin sheets of wood used as preliminary lining for internal walls, often covered with scrim or hessian before plastering or wallpaper.
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MCA – MICRONISED COPPER AZOLE
A timber treatment that is an alternative to CCA (Copper, chromium, arsenic).
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MDF
Medium-density fibreboard – made from wood fibres and resin, and commonly used for shelving, moulding and baseboards.
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MODELLING
Modelling, or thermal modelling, of the future performance of a home and its materials, insulation and ventilation systems is done using a software package to predict energy efficiency, heat losses and gains, and a range of other criteria for the whole house.  

Modelling is useful to identify areas where performance can be improved and problems solved by smarter design or choices of more effective materials or technologies, before the construction process begins – saving costly changes or retrofits later on.BRANZ guidance: 
‍GO TO LINK
and 
‍GO TO LINK

There are a range of modelling programmes including:
• NZ Green Building Council ECCHO (Energy and Carbon Calculator for Homes): 
‍GO TO LINK
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• Passive House NZ PHPP (Passive House Planning Package) – a requirement for compliance with Passive House Standard and Certification:
‍GO TO LINK
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MOISTURE BARRIER
A layer of material (typically plastic sheeting or treated paper) that prevents moisture from entering wall cavities, floors or ceilings. Critical for preventing mould, rot and structural damage in NZ's humid climate.
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MONITORING
Continuing assessment of the performance and energy efficiency of a home once it is completed and people are living in it. A range of monitoring technologies are available, from the basic sensors tracking interior CO2, temperature and humidity to more complex monitoring programmes collecting data on energy use, solar generation, water use, and the specific performance of particular systems in the home. Smart meters provide real-time information which can be tracked on the homeowner's phone.

Monitoring is key to identifying any problems or underperformance that need to be addressed to ensure the effective operation and cost efficiency of the home.

Monitoring is a requirement for all Certified Superhomes.

BRANZ guidance:
‍GO TO LINK
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MOULD
Approximately 50% of NZ houses are affected by mould, resulting from internal moisture and condensation on windows and interior surfaces.Mould can be a major health hazard and can cause allergic reactions, respiratory problems, asthma, eye irritations, sore throats and skin rashes. Some moulds produce toxic compounds, such as Stachybotrys (a greenish black mould that grows on timber, fibreboard, wallpaper and other materials).
Mould must be dealt with properly to ensure the safety and wellbeing of people living in the home:
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N
NZ GREEN BUILDING COUNCIL
The NZ Green Building Council (NZGBC), established in 2005, is a membership organisation of engineers, architects, builders, developers and suppliers, and industry associations. Its work includes the Homestar and Green Star certifications, training and advocacy:
GO TO LINK
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O
OUTSULATION
External insulation that is installed on the outside of the home, sometimes over the existing external cladding, to retrofit insulation to the home without having to remove the internal wall linings.
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P
PARAPET WALL
A continuous wall extending above the roof line around the front and sides of the home -- common in 1930s Art Deco homes. The low-pitched roof is not visible except from the rear of the house.


PARIS AGREEMENT
The Paris Agreement impacts our housing choices because of the need to reduce carbon emissions -- NZ housing is responsible for around 20% of the country's emissions with both embodied carbon (the materials and construction) and operational carbon (heating, lighting, appliances, energy efficiency, solar panels) -- and the need to future proof our homes for changing conditions including increasingly hot temperatures, flooding, and extreme weather.

New Zealand is committed to reducing greenhouse gas emissions to net zero by 2050. Housing renovations offer a major opportunity to reduce emissions through better insulation, efficient heating/cooling, and renewable energy.


PARTICLEBOARD
A low-density fibreboard or chipboard created from small wood particles and adhesive, compressed into panels or boards.


PASSIVE HOUSE
The Passive House Institute NZ (PHINZ) works to increase awareness of the benefits and opportunities of energy efficient buildings based on the Passive House Standard:
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Formal Passive House certification is granted after an independent verification process by an accredited Passive House Certifier:
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PILES
The piles are the solid posts or pillars that set the foundations of the house. They are usually made of concrete, with some older homes still having piles of timber or brick.The requirements for the piles for timber-framed houses are set out in NZS 3604:2011: BRANZ advice:
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PLASTER
A common finishing material for primarily internal uses on walls and ceilings, as well as some external uses, made with lime or gypsum (a soft calcium sulfate mineral):
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PLASTERBOARD
In NZ plasterboard is commonly known by the brand name GIB board -- made here since the 1920s, originally known as Gibraltar board, and one of the Superhome Movement's long-term partner supporters.Plasterboard is used for ceilings and wall linings, and has a structural bracing strength for additional earthquake resilience:
GO TO LINK
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It is made of gypsum plaster sandwiched between layers of sturdy facing paper. It is produced in many variations for particular uses and requirements including fire resistance, acoustics (reducing noise between rooms and floors in two storey homes), water resistance, mould resistance and curved walls.


PLYWOOD
Thin layers of wood veneer are glued together, with the grain (direction) of each layer alternating at 90 degrees for strength and stability. Plywood is stronger than particleboard and resists bending and splitting, giving structural resilience. Commonly used for wall and ceiling linings, subfloors and cabinetry.
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POLYBUTYLENE PIPING
Polybutylene (PB) plastic piping was used for plumbing in NZ homes from the 1970s to early 1990s, commonly known by the brand name Dux Quest. These pipes are prone to failure and leaking due to chemical degradation, especially when exposed to chlorine in water supplies. If your home has polybutylene piping, it should be replaced with modern piping systems to avoid water damage and insurance issues.
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PVC WINDOWS
See UPVC WINDOWS‍

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R
R-VALUE
The measure of thermal resistance. It quantifies how effective an insulation material is at resisting the transfer of heat. In simpler terms, a higher R-Value indicates better insulation performance. It means that the insulation is more resistant to heat flow, which is essential for maintaining consistent indoor temperatures and reducing the need for heating or cooling.
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RAFTERS
The rafters are sloping framing structures that support the roof of the house. Timber rafters in NZ homes are now often prefabricated. However if the design of the home includes complex shapes with wings or extensions, the rafters may also need to be complex. Rafter spacing and sizing is regulated under NZS 3604:2011: BRANZ guide:
GO TO LINK
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Exposed rafters can be a feature in many designer homes from the 1960s onwards.


RANCH SLIDERS
A sliding glass door, common from the 1960s onwards, using aluminium frames on a sliding track to maximise light and access.
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RED LIST
A listing by the US organisation Living Building Challenge (LBC) of chemicals representing the worst substances prevalent in the building industry that pose serious risks to human health and the environment:
GO TO LINK‍

Although Red List substances are present in many building products, safer and more natural alternatives, product designs and building designs are possible to avoid harmful chemicals in the structures of your home.Hazards include cancer, reproductive toxicity, acute or chronic organ toxicity, endocrine disruption, environmental persistence, bioaccumulation, ozone depletion, and others.
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RISING DAMP
Rising damp is a relatively rare form of damp that affects the walls of buildings. It occurs when moisture from the ground travels up through the walls by capillary action. This means that ground water is effectively sucked up through tiny tubes in the bricks, like a series of straws. Rising damp is often confused with damp caused by condensation.
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ROOF OVERHANG
The extension of the roof beyond the exterior walls. Provides weather protection, shading from summer sun (especially on north-facing walls in NZ), and helps prevent water damage to walls and foundations.
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S
SARKING
A protective layer installed under roofing materials to provide secondary weather protection, thermal performance and condensation control. Modern sarking products are breathable membranes that allow moisture to escape while blocking water entry.
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SASH WINDOWS
A typical window in turn-of-the-century villas, with two window sashes (top and bottom) that slide vertically supported by weights inside the window frame. The original windows may now have compromised weights and cords needing replacement or repair, and the original single glazing will need replacement with double glazing. If the timber frames are still in good condition, new double-glazed windows can be retrofitted into the frames.
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SCRIM
Scrim was used throughout the 19th and 20th century, before the development of plasterboard. It has been identified as a potential fire risk due to the nature of how it is manufactured and many insurance companies will refuse to insure a property where scrim or ‘sarking’ is present.
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SILICON SEALING
Commonly used to seal gaps and cracks to avoid draughts and heat escaping, and to waterproof areas around windows and doors.


SIPS
Structural Insulated Panel Systems. Each panel is a sandwich of a rigid panel glued to both sides of solid insulation. This replaces the whole timber frame and batts used in stick construction.
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SISALATION
Thin metal foil installed under floors and on some wall panelling from the 1970s onwards. Underfloor sisalation was often installed with a "draped sag" between joists with small holes for drainage of any moisture, compromising any insulation effectiveness.

Since 2016 it has been illegal to install or repair sisalation foil in residential buildings because of the risks of electrocution (under the Building Code Clause G9 Electricity) – sisalation foil itself is not illegal, but installation or repair is now banned:
GO TO LINK
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SKILLION ROOF
A low slope roof on a lean-to extension at the rear or side of a house. Skillion roofs are often joined to the exterior wall below the main roof line, and require good flashings to protect against water getting in to the structure and causing rot or mould.



SLAB FLOORS
Concrete slab floors are increasingly common in new NZ homes, particularly on flat sites. To meet Building Code requirements for structural performance they have reinforcing steel mesh and perimeter foundations tied to the slab with reinforcing steel. The Building Code Clause E2 establishes requirements for moisture control, and Clause H1 sets requirements for insulation.

Slabs should have a continuous layer of insulation underneath and around the sides, and can include water pipes or electrical cables embedded for heating and cooling.

MBIE guidance:
GO TO LINK
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SOFFITS
The underside of the eaves extending beyond the exterior walls of the home, or gable ends, to the edge of the roof line.



SOLAR GAIN
Heat increase in a space from direct sunlight through windows and other glazing. Good design maximises beneficial winter solar gain (through north-facing windows in NZ) while minimising unwanted summer heat gain through shading and glazing selection.
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STACK EFFECT
Natural ventilation driven by temperature differences. Warm air rises and exits through high openings (like clerestory windows), drawing cooler fresh air in through lower openings. This passive cooling strategy is particularly effective in NZ homes.
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STUCCO
A generic term for exterior coatings common from the 1920s onwards in NZ homes, made from cement, sand and water, with a more weather-resistant and rougher finish than interior plaster.

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THERMAL BRIDGING
Thermal bridging occurs when a component of the building with high conductive properties -- window and door frames, steel framing, metal studs and fixings, gaps in insulation, poorly designed timber framing – create a "weak point" which allows heat to pass through the insulation envelope. This impacts the amount of energy required to heat and cool the home, and the efficiency of your heating, cooling and ventilation systems. The cold areas created by thermal bridging can cause condensation and increase moisture loads in the home, contributing to mould risks.

Common thermal bridges include steel roofing purlins, aluminium window frames without thermal breaks, and gaps in insulation around framing.


THERMAL MASS
The ability of materials (like concrete, brick or stone) to absorb, store and slowly release heat. High thermal mass materials in floors and walls help regulate indoor temperatures by storing daytime heat and releasing it at night.


TONGUE AND GROOVE (T&G) TIMBER
A classic system in older NZ homes for interior walls, floors and ceilings, often made from native timbers. Planks are cut with a protruding edge or tongue along one side and a recessed groove on the other, creating strong links and an elegant profile.



TRANSLUCENT POLYCARBONATE SHEETING
Polycarbonates are strong plastic polymers that are commonly used for translucent roofing over decks and patios. Earlier products (1960s onwards) were vulnerable over time to cracking and clouding but more recent products have improved performance including options with UV protective coatings.

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UNDERLAY
A protective moisture-proofing layer running between the floor structures and foundations, wrapped around the external walls, and between the roof and roofing structures. Underlay (or building wrap) provides protection against moisture in the building structure and also helps with insulation and fire resistance.BRANZ bulletin:
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UNIVERSAL DESIGN
Universal design is design that is usable by all people, to the greatest extent possible, without the need for adaptation or specialized design.
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Universal design is the design of buildings, products or environments to make them accessible to people, regardless of age, disability, or other factors. Evaluating material and structures that can be utilized by all. It addresses common barriers to participation by creating things that can be used by the maximum number of people possible. Universal Design involves dilemmas and often difficult priorities. An example is Curb cuts/sidewalk ramps, which are essential for people in wheelchairs but also used by all.
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uPVC (Windows)
UPVC, (unplasticized polyvinyl chloride) windows are made from a plastic that is rigid and durable, making it a popular material for window frames. These windows feature multi-chambered profiles that provide excellent thermal and sound insulation.
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UREA-FORMALDEHYDE FOAM
Used from the 1970s onwards to retrofit insulation into the walls of older uninsulated homes, by drilling holes into the exterior cladding and pumping in a foam of urea-formaldehyde resin and compressed air. Concerns about effectiveness and moisture management were reviewed by BRANZ:
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There have also been concerns about health impacts of urea-formaldehyde foam insulation from the release of formaldehyde gas.


U-VALUE
The reverse of R-VALUE – measures the thermal conductivity of window glass and how well it insulates. A lower U-value indicates better insulation and energy efficiency.

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V
VAPOUR BARRIER
A material that prevents water vapour from passing through walls, ceilings or floors. In NZ's climate, vapour barriers are typically placed on the warm (interior) side of insulation to prevent condensation within wall cavities.


VILLA
A style of NZ home built primarily between 1880-1920, typically featuring a corrugated iron roof, timber weatherboard cladding, high ceilings, sash windows, and decorative fretwork. Villas often require significant upgrades for insulation, glazing and airtightness to meet modern standards.


VOCs – VOLATILE ORGANIC COMPOUNDS
Volatile organic compounds are gases that can affect indoor air quality and health, including headaches, nausea, irritation of the eyes, nose and throat, and damage to the liver, kidneys and central nervous system. Many VOCs are odourless. They are emitted at room temperature by many common products including paints, varnishes, flooring, building materials, insulation, furnishings and adhesives. VOCs common in building materials include formaldehyde, benzene, and xylene.

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W
WEATHERTIGHTNESS
A key element in any building is how well it prevents water from getting in to the structure, with implications for internal moisture, the risk of mould growth, and impacts on the health of the residents, but also major importance for the durability of the home and its compliance with the Building Code clause B2 Durability. Factors include design, permeability of materials, watertightness and wind resistance.BRANZ has provided information on designing and constructing for weathertightness and offers services to test the performance of different construction systems and materials:
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