Large aluminium windows flood a room with light and turn a view into a feature wall. Aluminium is the right material for them, because its strength lets a slim frame carry a big pane. But every window type has a limit on how large a single opening sash can be, so a big opening is usually built from several panes. This guide explains the largest sizes in the Coetz™ range, the sash limits, how to combine panes, and the rules for large glass.
In this guide
The largest standard sizes
| Window type | Largest standard size (mm) | Example price (White, excl. VAT) |
|---|---|---|
| Sliding (Premier) | 4 800 × 1 800 | R36 466, 4 panel |
| Sliding (Horizon) | 4 800 × 1 800 | R29 058, 4 panel |
| Fixed | 3 600 × 2 100 | R14 164, 6 pane |
| Top hung | 3 000 × 1 800 | R11 515, 4 pane |
| Side hung | 2 400 × 1 800 | R9 190, twin opener |
Prices are at the time of writing (October 2026). Each of these large aluminium windows is made in 1–2 days.
Sash limits
The opening part of a window, the sash, has a maximum size and glass weight set by the manufacturer:
| Window type | Largest sash (W × H) | Max glass weight |
|---|---|---|
| Top hung | 1 200 × 1 000 mm | 30 kg |
| Side hung | 600 × 1 200 mm | 30 kg |
| Standard sliding | 1 500 × 1 800 mm | 45 kg |
| Premier sliding | 1 500 × 3 000 mm | 160 kg |
| Horizon sliding | 2 000 × 3 000 mm | 150 kg |
That is why large aluminium windows are made of several panes: a 3 000 mm top hung window, for example, is a mix of fixed panes and top hung openers, each within the limit.
Combining panes
Large aluminium windows are usually a combination:
- Fixed panes for the view, with no sash to interrupt it.
- Openers for air: top hung vents above or beside the fixed panes, or side hung sashes.
- Sliding panels for a wide opening that also lets in a lot of air; Premier and Horizon sliding windows take the biggest panels.
Coetz™ top hung windows come in layouts with full-height side vents and 600 or 900 mm vents above fixed glass, which suit a wide window that still needs ventilation. See fixed vs opening windows and top hung aluminium windows.
Glass in large windows
Every Coetz™ window uses 6.38 mm clear laminated safety glass, which holds together if it breaks. Large, low panes are exactly where the regulations require safety glass. See where safety glass is required and SANS 10400-N, published by the South African Bureau of Standards.
Wind, height and sign-off
Large windows high up on an exposed site carry bigger wind loads, so frame depth matters; the 36 mm heavy-duty frame suits bigger windows on exposed walls. The manufacturer also notes that external glazing more than 10 m above ground level must be signed off by a competent person (glazing). See wind loads on aluminium windows and aluminium window frames.
Planning large aluminium windows
- Measure the opening and check the lintel above can carry the span.
- Decide view and ventilation: where you want fixed glass and where you want openers.
- Split the opening into panes within the sash limits.
- Choose the frame depth for the size and exposure.
- Plan delivery and handling: large frames are heavy and need at least two people.
Living with large windows
Big glass brings big views, but also more sun and heat. On north and west walls, an overhang or covered patio keeps summer sun off the glass while letting winter sun in. Blinds or curtains give privacy at night, when large aluminium windows show the inside of a lit room to the street. Clean big panes from a safe position, and use a long-handled squeegee rather than leaning out of a sash.
Ordering
Coetz™ supplies large aluminium windows only; your builder or installer fits them. We deliver across South Africa, or you can collect free from Laser Park. For standard sizes, see aluminium window sizes.
Large aluminium windows: frequently asked questions
What is the biggest aluminium window you make?
Sliding windows go to 4 800 × 1 800 mm, and fixed windows to 3 600 × 2 100 mm.
Why does a big window have several panes?
Each opening sash has a maximum size and glass weight, so large windows combine fixed panes and openers.
What glass goes in large windows?
6.38 mm clear laminated safety glass, as in every Coetz™ window.
Do large windows need a heavier frame?
On exposed sites, the 36 mm heavy-duty frame is a good choice for larger windows.
Who signs off glazing on tall buildings?
External glazing more than 10 m above ground must be signed off by a competent person (glazing).
Coetz™, Unit 2, 84 Ridge Road, Laser Park, Johannesburg. Call 010 412 0062, WhatsApp 076 613 4418 or use our contact page.
Leave a Reply