uPVC or aluminium: which should you actually specify?
They are not competitors so much as different answers. One insulates, one spans. The honest comparison, from a manufacturer that sells both.
We manufacture both, which means we have no particular reason to talk you into either. The choice is genuinely situational, and most of the advice online is written by someone who only sells one of them.
What uPVC is better at
Insulation. This is not close. uPVC is a poor conductor of heat, and the profiles are multi-chambered, so the frame itself resists heat transfer. The TwinSash system reaches as low as 0.8 W/m²K with double glazed units. Aluminium conducts heat well — which is exactly what you do not want in a window frame — and needs a thermal break to compensate.
Noise. The same multi-chamber construction, plus double seal technology, is what allows reductions of up to 40 dB with the right glass.
Not corroding. uPVC does not rot, split, warp or corrode, and it is termite proof — which matters more in this climate than it does in the European markets these systems came from. Wooden frames swell through the monsoon; uPVC does not.
Cost. Generally lower, for equivalent performance.
What aluminium is better at
Span. Aluminium is stronger, so it holds more glass with less frame. If the opening is large, aluminium will do it with a lighter-looking frame.
Sightlines. The aluminium series carries a visible frame of only 19 mm and a central section of 20 mm. Nothing in uPVC gets close to that. If the brief is "as much glass and as little frame as possible", the conversation is over — it is aluminium.
Load. The aluminium sliding system carries a wing load of 500 kg on two carriages, running on a stainless steel double guide.
Where it gets less obvious
Large uPVC openings are possible. Heavy Duty Patio Doors run to 5.8 m wide and 3.0 m tall with a 300 kg sash, on a 142 mm outer frame housing two 62 mm sashes. That covers most residential openings, in uPVC, with uPVC's insulation.
So "big opening means aluminium" is not automatically true. It becomes true when you want the big opening and a slim frame.
A rule of thumb
- Bedrooms, and anything facing a road or the afternoon sun → uPVC, for the thermal and acoustic performance
- Living rooms opening onto a garden or terrace, where the view is the point → aluminium, for the sightline
- Large openings where budget is the constraint → uPVC, using the heavy-duty patio system
- Commercial facades, structural glazing, railings → aluminium, by default
Mixing them
There is no rule against using both in one building, and on most projects it is the right answer: aluminium where the glass area is the architecture, uPVC everywhere else. Because both come from the same factory here, the finishes match and there is one installer and one point of accountability.
Compare the two ranges directly — uPVC windows and aluminium windows — or send us the elevation and we will mark up which system belongs in which opening.