Vertical sliding windows open by sliding a glazed sash up or down inside the frame instead of swinging outwards on hinges. They are the modern aluminium version of the traditional sash window, sometimes called a vertical slider, and they suit any spot where an outward-opening window would get in the way: beside a walkway, over a patio or next to a driveway.
This guide explains how vertical sliding windows work, how they compare with horizontal sliding and top hung windows, the sizes and frame systems Coetz™ makes, and what they cost. Every price is a real shop price, excluding VAT, in White with 6.38 mm clear laminated safety glass.
Contents
How vertical sliding windows work
Each window has a sash that runs up and down in channels in the side of the frame. On Coetz™ windows in this range the sash moves on a counter-balanced mechanism, so it glides smoothly and stays where you leave it instead of dropping shut. A Fitch catch locks the sash closed and a handle is included as standard.
Because the sash never leaves the plane of the wall, nothing projects outwards. That makes them safe beside paths, braai areas and parking bays, where someone could walk into an open top hung or side hung window. Ventilation comes from the top or bottom of the opening.
Sash windows, vertical sliders and vertical sliding windows
These names describe the same idea:
- Sash window – the traditional name, from timber windows where weights and cords balanced the sash.
- Vertical slider – common shorthand in the trade.
- Aluminium vertical sliding windows – the modern, rust-free version, with powder-coated aluminium frames instead of timber that needs painting.
If you are restoring a period home, aluminium sash windows give you the classic sash proportions without the rot, swelling and repainting of timber.
Vertical vs horizontal sliding windows
Both types slide instead of swinging, so neither projects into the room or outside. The difference is the direction:
| Vertical sliding windows | Horizontal sliding windows | |
|---|---|---|
| How it opens | Sash slides up and down | Panels slide sideways on a bottom track |
| Best shape | Taller than wide | Wider than tall |
| Coetz™ sizes | 600 – 1 200 mm wide, 900 – 1 500 mm high | 900 – 4 800 mm wide, 600 – 1 800 mm high |
| Price from (excl. VAT) | R3 494 | R3 192 |
| Look | Classic sash proportions | Modern, wide view |
Choose a vertical slider for narrow, tall openings and a traditional look; choose horizontal sliding windows for wide openings and an uninterrupted view. For openings where projection does not matter, top hung windows are the most popular and usually the most affordable choice.
Vertical sliding window sizes and prices
Coetz™ makes aluminium vertical sliding windows to order in eight catalogue sizes, each in a Standard Frame or a 44 mm Commercial Frame. The actual frame is 10 mm smaller than the catalogue size in each direction, which leaves room to fit it into the opening.
| Size (W × H) | Standard Frame | 44 mm Commercial Frame |
|---|---|---|
| 600 × 900 mm | R3 494 | R3 941 |
| 600 × 1 200 mm | R4 214 | R5 643 |
| 600 × 1 500 mm | R4 411 | R6 096 |
| 900 × 900 mm | R4 203 | R5 249 |
| 900 × 1 200 mm | R4 620 | R6 017 |
| 900 × 1 500 mm | R5 093 | R7 025 |
| 1 200 × 1 200 mm | R5 327 | R7 284 |
| 1 200 × 1 500 mm | R6 587 | R8 805 |
Prices are excluding VAT, in White, as at 19 October 2026. The shop and the online estimator always show the current price. To check which size fits your opening, see how to measure aluminium windows and our guide to aluminium window sizes.
Standard Frame or 44 mm Commercial Frame?
- Standard Frame – the everyday vertical sliding sash frame, suited to most residential openings.
- 44 mm Commercial Frame – a heavier 44 mm outer frame for larger openings and a more substantial sightline, suited to busier buildings.
Both frames come with the same hardware and the same 6.38 mm clear laminated safety glass. If you are unsure, the Standard Frame suits most homes; choose the Commercial Frame for the larger sizes or where the window will be used heavily.
Where vertical sliding windows work best
- Beside walkways and paths – nothing projects outwards, so nobody walks into an open sash.
- Over patios and next to driveways – fresh air without a window swinging into the space.
- Period and heritage homes – classic sash proportions in low-maintenance aluminium.
- Narrow, tall openings – where a horizontal slider would leave panels too narrow to be useful.
They are also available as a sidelight beside a door, in the 75 mm frame – see toplights and sidelights.
Glass, colours and supply
All windows in this range are glazed with 6.38 mm clear laminated safety glass, which holds together if it breaks and meets the safety-glazing rules in SANS 10400-N, published by the South African Bureau of Standards. They come in White, Bronze, Charcoal and Black; Bronze and Charcoal cost the same as White and Black costs about 10% more. Natural Anodised is not offered on this range.
Coetz™ makes every window in this range to order in 1–2 days and supplies them nationwide. We supply only, so your builder or installer fits them. Browse the full vertical sliding windows range or every type on our aluminium windows page.
Looking after vertical sliding windows
Wipe the side channels and the sill clean so grit does not wear the seals, keep the drainage holes at the bottom of the frame clear, and wash the frames with mild soapy water. Never force a sash that sticks: clean the channels first, then ask your installer to check it. See how to clean aluminium windows for a full care routine.
Aluminium vertical sliding windows as sidelights
Vertical sliding windows also come as narrow sidelights beside a door, in our 75 mm frame, so the door and the opening light match:
| Vertical sliding sidelight | Price (excl. VAT) |
|---|---|
| 600 × 2 100 mm | R6 299 |
| 600 × 2 400 mm | R7 049 |
| 900 × 2 100 mm | R7 749 |
| 900 × 2 400 mm | R8 351 |
See toplights and sidelights for the other sidelight frames. Like all our vertical sliding windows, the sidelights are supply only and glazed with laminated safety glass.
Vertical sliding windows: frequently asked questions
What is a vertical sliding window?
It is a window whose sash slides up and down inside the frame instead of opening outwards on hinges. It is the modern aluminium version of the traditional sash window.
Are vertical sliding windows the same as sash windows?
Yes. A sash window is the traditional name for this type of window. Aluminium versions keep the sash look but do not rot, swell or need repainting.
What sizes do vertical sliding windows come in?
Coetz™ makes eight sizes: 600 mm wide at 900, 1 200 or 1 500 mm high; 900 mm wide at 900, 1 200 or 1 500 mm high; and 1 200 mm wide at 1 200 or 1 500 mm high.
How much does a vertical sliding window cost?
Coetz™ prices start at R3 494 excluding VAT for a 600 × 900 mm window in the Standard Frame, up to R8 805 for 1 200 × 1 500 mm in the 44 mm Commercial Frame, in White.
Which is better, vertical or horizontal sliding windows?
A vertical slider suits tall, narrow openings and a classic look; horizontal sliding windows suit wide openings and a modern view. Neither projects outwards.
Can I get vertical sliding windows in Natural Anodised?
No. This range comes in White, Bronze, Charcoal and Black. Natural Anodised is not offered on this range.
Replacing old timber sash windows? See aluminium sash windows.
