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.
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.
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.
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.
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.
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.