What you cannot see in a showroom
Two uPVC sliders sitting side by side can look identical and cost very different amounts. The difference is inside.
Steel reinforcement
uPVC profiles are hollow and multi-chambered. Over any real span they rely on galvanised steel inside those chambers to carry load, resist wind and constrain thermal movement.
uPVC expands and contracts more than aluminium with temperature. On a Mumbai west elevation that is a meaningful daily cycle, and reinforcement is what keeps a wide sash straight through it. Omitting or undersizing it is the single most common corner cut, and it shows up as a bowed frame two summers later.
Roller load rating
Rollers carry the whole sash on a small contact patch. Specified for the actual glass weight — including a sealed unit if you are double glazing — they last for years. Specified optimistically, they flat-spot and the window becomes heavy to move.
Track drainage
The bottom track is a drained gutter. Weep holes have to be correctly sized and positioned, and the track detailed so water runs to them. This is what separates a slider that copes with monsoon from one that puts water on your floor.
Why uPVC rather than aluminium
Thermal. uPVC is a poor conductor. An aluminium frame without a thermal break conducts outdoor heat straight into the room; on a sunny elevation you can feel the difference in the frame itself.
Acoustic. The multi-chambered section damps sound better than a hollow metal one.
Cost. For equivalent performance, generally lower.
Maintenance. No repainting, no corrosion in coastal air.
Aluminium wins where you need very slim sightlines or a span uPVC cannot reasonably reach. For most flats, uPVC is the right default — see best uPVC windows in Mumbai for the fuller comparison.
Configuration
Two, three and four-track systems, with the choice driven by how much of the opening needs to clear and how deep a frame the reveal will accept. The general sliding windows page covers the track systems in detail.
An insect screen can run in its own track on a three or four-track system, which is much neater than a retrofitted screen — worth deciding at order rather than later. See insect screens.
Finish
Foiled profiles in woodgrain and solid colours, inside and out, and the two do not have to match. Because the colour is in the foil rather than a paint film, there is nothing to flake or repaint. See colour options.
Made here
We fabricate these in Bhandup West, so sizes follow your survey rather than a stock list, and the reinforcement and roller specification are decisions we make rather than inherit. See how we manufacture.