Glass is most of the area of a folding or sliding door, so it decides how the room feels in August as much as the frame does. These are the options we quote and how to match them to an opening.
Safety first: tempered and laminated
Door panels must be safety glass. Tempered (toughened) glass is heat-treated so it is several times stronger than ordinary glass and breaks into small granules. Laminated glass bonds two sheets with a plastic interlayer; if broken it stays in place, which improves security and reduces noise. Laminated glass can also be tempered. For ground-floor villa openings and homes near main roads, laminated is worth considering.
Heat: double glazing and low-emissivity coatings
A double-glazed unit has two panes with a sealed cavity. The cavity slows heat transfer; a low-emissivity (low-E) coating on one pane reflects a large part of the sun's heat while letting light through. For air-conditioned rooms with sun-facing glass, this combination is the usual specification. Single glazing is reserved for shaded, unconditioned or lightly used openings. A thermal-break frame completes the picture by reducing heat through the aluminium itself.
Glare and privacy
Tinted glass (grey, bronze, blue) reduces glare and visible light; reflective glass does the same with a mirror-like exterior in daylight; frosted or sandblasted panes give privacy on specific panels, for example bathrooms or the side facing a neighbour. Each can be one pane of a double-glazed unit.
Noise
Laminated glass and asymmetric double glazing (panes of different thickness) reduce noise more than ordinary double glazing. If the opening faces a road, say so when enquiring.
Weight and the system
Thicker and laminated glass is heavier. On slim sliding doors the glass build-up can set the maximum panel size; on folding doors it affects the hinges and rollers specified. The quotation states the exact build-up and confirms it is within the system's limits.
A short guide by opening
- Sun-facing living room, air-conditioned: double glazed with low-E, thermal-break frame if the budget allows
- Shaded terrace, often open: tempered single or standard double glazing
- Ground floor near a road: laminated outer pane in a double-glazed unit
- Bathroom or boundary-facing panel: frosted pane
See the options for folding doors and slim sliding doors.
