Frequently asked questions

See our Glossary for any terms you want to clarify

The uPVC profile undergoes precision cutting and welding, with steel insertion and the fitting, testing, and glazing of opening and locking hardware all taking place in our Christchurch factory. Our glass is custom processed and cut by Viridian Glass. 

PVC is short for polyvinyl chloride, a type of plastic widely used in construction and various industries since the 1950s. uPVC, or unplasticised PVC, is a specific form of PVC that is highly suitable as a material for window frames. 

Its versatility allows it to be used in diverse applications, ranging from window frames and pipes to medical products. 

Absolutely. The roots of uPVC windows trace back to 1959 when the first commercially available windows graced homes in Germany. Over the years, technology has advanced, and yet, some of those initial uPVC windows are still standing strong. In fact, more than 60% of European homes now boast the reliability of uPVC windows and doors. 

Yes. Viewed across its lifecycle, uPVC is highly competitive in terms of environmental impact. Several recent eco-efficiency and Life Cycle Assessment (LCA) studies on the most common applications show that, in terms of energy requirements and GWP (Global Warming Potential), uPVC is at least equal to alternative products. In many cases, it shows advantages both in terms of total energy consumption and lower CO2 emissions.

The core materials for uPVC production – chlorine and ethylene – are both by-products of other manufacturing processes. Chlorine is a by-product of caustic soda production with source raw materials of seawater and rock salt. Ethylene is a by-product of the petroleum refining industry i.e. PVC is not directly dependent on crude oil. 

Our frames are also highly recyclable.

Absolutely. Our PVC profiles specifically engineered with New Zealand’s climate in mind, including those intense UV rays. The same robust formula stands resilient in other high UV environments such around the world, such as the Middle East, Australia and Latin America. 

Definitely. Many of our customer projects involve renovations. We understand the importance of preserving character, and our robust uPVC frames are perfect for bungalows and villas.

Yes! We offer a full range of outward-opening windows, with traditional or contemporary styling. Find out more here

No. “uPVC windows” refers only to the frame material. We have access to the same glass options as any window supplier through our partnership with Viridian Glass based in Christchurch. Most common options include: 

  • LightBridge Double Glazing – includes argon and Low E 
  • Laminated glass for improved security and noise reduction
  • Obscure glass for increased privacy
  • Tinted glass for improved privacy and reduced solar gain

Aluminium – there are several reasons to choose uPVC instead:

  1. Thermal performance – aluminium is highly heat conductive so they are not well suited to temperate climates and houses fitted with them require additional energy consumption for heating and cooling and often suffer condensation problems. See here for more detailed information.
  2. Health – condensation breeds mould and with mould come dangerous spores. Such environments have been proven to be associated with respiratory illnesses: nose and throat symptoms, cough, wheeze, and asthma symptoms. There is also evidence that these environments can be associated with shortness of breath, the development of asthma in people who did not previously suffer from it, and lower respiratory symptoms (coughing, wheezing, chest tightness, and shortness of breath).
  3. Environmentally responsible – aluminium is produced from the non-renewable ore, bauxite. Aluminium production requires a great deal of energy (225MJ/kg) and it generates huge amounts of environmentally dangerous pollutants like carbon dioxide, acidic sulphur dioxide, along with polyaromatic hydrocarbons (PAHs) fluorine and dust. Although New Zealand does produce aluminium, all raw materials are imported: bauxite/alumina from Australia, crude oil from Alaska USA, and coal from China and Korea – again adding to the environmental impact of aluminium windows. See here for more information.

 

Wood – there are equally strong arguments for choosing uPVC over wood:

  1. Environmentally responsible – most people believe using wood is the most environmentally sensible option for window frames because of the “natural is better than synthetic” assumption. But if wooden frames are to maintain their technical and thermal properties, they require regular treatment with chemicals that are often very environmentally unfriendly.
  2. Lifecycle – DEFRA (Department for Environment Food & Rural Affairs – UK government) commissioned a study into the lifecycles of PVC and timber in window profiles. In analysing the various impacts across the lifecycle, it was found that there are only marginal differences in the environmental performance between the two. Although trees are not a scarce resource, the facts around de-forestation, particularly logging of ancient or old-growth forests, warrant further understanding. The logging of these forests can lead to a decrease in biodiversity, as habitats are destroyed in the logging process. Tree plantations are grown, in their place, for the intense farming of timber and wood products. This itself can lead to soil erosion and nutrient degradation, vulnerability to pest attack, reduction in water supply, over use of fertilisers and social impacts.
  3. Sustainability – Caution needs to be taken in accepting claims of an increase in forested areas. Scandinavia presents an interesting example relating to the misconceptions surrounding so-called ‘sustainable forestry’. Eco watchdog, Friends of the Earth comment: “More trees are not a good thing when they are replacing valuable wildlife habitats. Scandinavia has now just 5% of its original old-growth forest remaining, yet this is still being logged. Also almost 50% of Finland’s peat bogs have been drained, mostly for planting managed forests.”
  4. Quality –  like most items of organic origin, not all wooden windows are the same. There are good quality and poor quality wooden windows available in NZ. Poor quality wooden windows can warp and delaminate. uPVC gives you a quality finish, every time.

Regular cleaning and maintenance are essential for all windows, as they can accumulate stains and damage over time due to pollution, weather, and various other factors. By adhering to proper cleaning and maintenance guidelines, you can optimize the appearance, functionality, and longevity of your windows.

See our After-care section to assist you in caring for your windows.

Navigating the regulations for planning permission can be intricate and perplexing. Permitted Development offers the opportunity to undertake specific home development projects without planning permission. However, it is crucial to adhere to planning guidelines to prevent any costly errors. Contact our team to find out more.

Under normal circumstances you will not need a builder if replacing windows and doors, we will do the work required. However, we do not carry out structural work, so in that case, the services of a builder would be required.

Special features of NK Windows

Tilt & Turn windows and doors were developed in Germany in the 1940s and are widely used in the UK and Europe. Although available in New Zealand for more than 20 years, the Tilt & Turn system is often met with surprise and intrigue.

Tilt & Turn windows and doors provide dual functionality, allowing the same sash unit to tilt inwards and turn inwards, as determined by the handle position.

Tilt & Turn windows and doors provide multipoint locking on 2, 3 or 4 sides as standard depending on the size of the window or door. On most non-locking sides a hidden compression device is used to stop the frame flexing or lifting if someone attempts to pry it open. These features provide exceptional security benefits and peace of mind.

Internal glazing beads mean the glass can only be installed and removed from inside the house – it cannot be removed externally.

The tilt opening provides excellent ventilation security at street level and is impossible for a child to climb out of. A window can be locked in the tilt position if a locking handle is fitted. Restrictors can be fitted for child safety.

The tilt position allows daytime gentle air movement ventilation whilst maintaining high levels of security and safety with a 120mm opening. The tilt position can be safely used during periods of rain.

In the turn position, large amounts of ventilation can be achieved quickly.

A night venting option is available that provides a 10mm tilt opening.

The turn position allows easy access to the exterior frame and glass surfaces for safe cleaning. 

Yes, no problem. Triple glazing can improve the thermal performance by over 35% compared with double glazing.

 

Yes. We have installed windows in high wind areas such as Mt. Cook Village, Twizel and Scott Base in Antarctica!

uPVC windows achieve a European fire classification of DIN EN 13501-1 Class E. uPVC is an inherently fire-resistant plastic, an exception in the world of plastics.

When PVC products are burned, hydrogen chloride gas resulting from thermal cracking slows down the continuous combustion reaction and prevents burning progress by warding off the PVC product surface from oxygen in the air. The gas is also detectable by its highly unpleasant odour at concentrations well below those that could be harmful to health. This feature allows early detection of a fire.

 

Yes. Consideration should be given to placement of curtains and blinds to allow for inward opening. Alternatively our windows and doors are well suited having blinds fitted to the sash. We partner with Cosiflor to provide TwinGo Blinds that are specifically designed for PVC frames.

 

Yes. We partner with Homeplus who offer a variety of styles and functional designs that work very well with inwards opening windows and doors.

 

Yes. We carry several models in stock and can source others if required including micro-chip controlled access for up to 10 pets.

 

Importing and retrofitting

No, it’s not a good idea for a number of reasons!

  1. Climatic suitability – the PVC profiles imported by NK Windows are of a formula optimised for the very high levels of UV radiation New Zealand has and of a profile design optimised for South Island winter temperatures. Any PVC imported – especially cheaper PVC – on a DIY basis is very unlikely to be well suited to South Island climatic conditions.
  2. Approvals – windows need to be approved by governing bodies in New Zealand. The approval process is expensive i.e. 10’s of thousands of dollars and time consuming and of course there is no guarantee they will actually be approved. Installing unapproved windows is illegal.
  3. Additionally, some DIY importers have come unstuck when importing glass that does not meet NZ safety standards. What can start out as a money-saving exercise can easily become very expensive!
  4. Support – importing critical products that are not supported locally comes with significant risk.

If you want to achieve an airtight seal, optimise thermal performance from the glass & frame and get good value for money, then no, it’s not a good idea.

  • Double-glazing adds a lot of extra weight to a window that the original sash and hardware were never designed to cope with. Sagging along with poor sealing are typical problems people will face after a short time.
  • Adding double-glazing does not address the issue of poor performing frames in terms of aluminium being a good thermal bridge and poor sealing.

Most of our windows and doors are installed by our own teams. We do offer a supply only arrangement if you want your builder to install, and we also have qualified regional partners that will install on our behalf in locations where it is not viable for our teams to travel.

Installation questions

It depends on the number of windows and doors to be installed and the complexity of the job including heights, hill sections, access, etc. We install a typical house lot of windows in 3-4 days. Our installation teams won’t leave your house unsecured overnight, and will also be fully compliant with H&S regulations.

Most of our windows and doors are installed by our own teams. We do offer a supply only arrangement if you want your builder to install, and we also have qualified regional partners that will install on our behalf in locations where it is not viable for our teams to travel.

Manufacturing questions

NK Windows partner with German-based aluplast GmbH for PVC profile systems. They are world-leaders in the field and focus solely on PVC for window and door systems. Their products are used around the globe. The raw materials used by aluplast for window profiles are based on a calcium-zinc chemical stabiliser that is strictly lead-free. With this eco-friendly stabiliser and aluplast’s involvement in “VINYL 2010”, that among other things dictates the use of recycled materials in their plastic profiles, aluplast offers window systems that can be fabricated and recycled in an ecologically sound way.

It comes from proven European hardware manufacturers Maco Group (Austria) and Roto-Frank (Germany) and New Zealand based Windsor Brass. All 3 vendors produce exceptionally well designed and precision engineered hardware componentry to the world. We are proud to offer their stylish, innovative, highly reliable and secure products to you including 50+ handle and lock combinations.

 

Yes, they represent exceptional value for money over their whole-of-life. No costly or environmentally damaging maintenance is required and their thermal performance outperforms aluminium (including thermally broken aluminium) hands-down, which equates to monthly energy bill savings in summer and winter. A warmer dryer home provides a more comfortable healthier environment meaning less sick days, greater productivity and less hospital admissions.

 

Let’s talk about your project

Whether you’re starting a renovation project or building new, the path to creating homes that stand out starts with NK Windows. No matter the size of your project or the scope of your vision, our team is here to guide you through every step of the process.  

You can trust us to turn your dreams into reality and your house into a home.

Download our inspirational guide to choosing windows and doors

Everything you need to know about choosing the right windows and doors for your project with tips and advice, resources and much more.