uPVC doors and windows: Everything you need to know


While not as popular in New Zealand as aluminium framing, uPVC is a modern, European approach to windows. Although both have their ardent advocates, uPVC has some slight advantages worth considering over the widely used metal.

New Zealand housing

uPVC has been gaining some traction over the last few years, but it’s yet to become quite as popularised as aluminium. The reason builders have traditionally preferred this material is to do with the way New Zealand homes are built. Our timber-framed external walls are typically less able to withstand moisture buildup and require a fair amount of drainage. Aluminium windows aren’t susceptible to water damage and are installed outside the wall frame providing a ‘moisture-gap’, which lets the excess water drain away. Unfortunately, this becomes the main area for heat escaping and water condensing on a cold aluminium surface.

As we improve our building methods and installation, this method needs to change. Aluminium as a material is a very poor insulator, which is why uPVC is often used to achieve better results. Combined with recessed installation, it is the biggest improvement you can make to your house’s thermal performance. 

Another point worth considering is that manufacturing standard aluminium windows is less expensive than PVC processing, which requires more machinery investment. Where European economies of scale come to the fore is where you can take advantage of less expensive avenues of production. 

What is uPVC?

uPVC stands for unplasticised Polyvinyl Chloride, an extremely durable, low-maintenance plastic-like substance often used to substitute for painted wood. 

So why use one over the other?

If you’re tossing between uPVC and aluminium window framing for your new or existing build, you might want to consider the following factors;

Thermal insulation

uPVC windows have some of the best insulation properties regarding window and door frames. Our own Koffman models are certified with an R-value (thermal resistance) of 1.39, which is over five times higher than the New Zealand current standard and over two and a half times better than the new H1 proposal for coldest regions.

Unlike the traditional solid window frame, a uPVC frame contains what looks like a ‘honeycombed’ series of small chambers, which increases the material’s strength and insulative quality.

Sound insulation

uPVC windows are also among the quietest. Depending on the amount of glazing used, a uPVC window can reduce up to 47dB’s (decibels) of noise.


Using properly fitted window panes and sealants will also prevent gaps from appearing, whether you choose aluminium or uPVC window framing. Minimising these gaps is critical in avoiding heat seepage around windows and doors and will help your frames perform at their very best.


A typical factor in heat loss isn’t just the frame but also the glass used inside the frame. We suggest at least using double-glazing with low E glass and a layer of argon gas between the panes. 

Koffman’s window framing is 76 or 88mm thick, with the latter having the best sound and heat insulation quality. Both allow for triple glazing units up to 52mm thick to be used.


The greater the number of panes, the harder it is to break into a window. This adage is particularly true when reinforced with a strong, durable material such as uPVC. The strength of the material comes from its vinyl polymer manufacture, which is a process that combines chlorine atoms to make something that is strong, flexible, and that can combine easily with steel.

Koffman windows also include multiple locking points and glass fitted from the inside, making it virtually impossible for potential intruders to separate the glass and frame components.


Because of its strength and durability over traditional metals, uPVC has also replaced most plumbing, weatherboarding and drainage systems. Basically, this isn’t a frame you have to worry about getting wet! Koffman’s double or triple seal system keeps windows weathertight even in high wind zones.


Because of the low-density strength of the material, uPVC frames can be made extremely thin whilst still holding their structural integrity. This is also due to the way the frame is constructed, with the ‘honey-comb’ structure reinforcing the material’s strength against accidental bumps, crashes and balls thrown against the house.

Opening types

We offer both standard bifold and sliding window types. Both are terrific options for letting more air into your rooms whilst keeping your windows secured on a slider. 

The other more adventurous options we offer include tilt or turn windows and doors, which let you open your windows from the side, as you normally would, and from the top, to allow ventilation even when raining. Our doors have an additional tilt and slide option, which means they swing open like normal French doors and can be tilted from the top to allow for ventilation.


uPVC’s most noticeable (or unnoticeable) feature is its colouration. Many coatings systems have been developed with vinyl or acrylic foils which are fully bonded to the base frame and can be made to look like real textured wood or other materials.


uPVC can also be extended to include clip-on aluminium cladding, which combines the advantages of both materials and gives the exterior a metal finish. 


The cost of uPVC varies, with some companies citing it as the more expensive over aluminium. However, that largely depends on the cost of shipping and overseas manufacture, as New Zealand has historically relied much more on aluminium. 

At Koffman’s, we design and ship all our products from overseas, using the best European techniques. All our projects are based on a quote system, depending on the specific build requirements.

Sites sourced:
  • “Aluminium vs uPVC Windows (Pros and Cons Reviewed)” on The Aluminium Door Company. Date Accessed: 13th July, 2022. Site Link: https://bit.ly/3cbQkkD
  • “Aluminium vs uPVC windows – Which is better?” on Checkatrade. Date Accessed: 13th July, 2022. Site Link: https://bit.ly/3axaZ2a
  • Burgess, John. “Could windows be installed better?” on Build NZ. Date Published: 1st December 2017. Link: https://bit.ly/3Q9Z3Ds
  • Gupta, Surbhi. “UPVC windows: All you need to know” on Housing.com. Date Published: 16th February, 2022. Site Link:  https://bit.ly/3Slk9zU
  • “Levels of Noise in Decibels (dB) Level Comparison Chart” on Sound Proofing Guide. Date Accessed: 5th August, 2022. Site Link: https://bit.ly/3byudoO/
  • “Rethinking our windows—the case for using uPVC in New Zealand” on ArchiPro. Date Published: 21st July, 2021. Site Link: https://bit.ly/3OQnghl
  • “uPVC vs Aluminium” on Hazlemere. Date Accessed: 13th July, 2022. Site Link: https://bit.ly/3yB3uPP
  • “What is uPVC?” on Hazlemere. Date accessed: 5th August, 2022. Site Link: https://bit.ly/3yB3uPP