Windows
Cortizo Aluminium Sliding Windows
About Cortizo Aluminium Sliding Windows
Our Cortizo sliding windows use the Cortizo 4900 Sliding HI system, a thermally insulated aluminium slider with good acoustic performance and a smooth, light action. The sashes slide past one another rather than swinging open, which suits windows onto balconies and walkways or anywhere an opening sash would get in the way. Layouts run from two to six sashes on up to three rails, with a slim 35mm interlock, glazing up to 36mm and windows up to 2,200mm wide by 2,600mm high. Acoustic insulation reaches Rw 40 dB. Finishes cover the whole RAL chart, plus mottled, textured, wood-effect and anodised options.
On homes, aluminium sliding windows suit kitchens over a worktop, where reaching out to push a casement is awkward, and rooms opening onto a balcony or terrace. On apartment blocks and offices, they suit windows onto walkways and balconies, where an outward-opening sash would get in the way, and the Rw 40 dB acoustic rating helps on busy streets. The 4900 HI is tested to Class 4 air permeability, Class 7A water tightness and Class C5 wind resistance.
In England, a replacement window in an existing home needs a whole-window U-value of 1.4 W/m²K or better, or a Window Energy Rating of band B, under Approved Document L. The U-value depends on the glass and the size of the window, so we confirm it with the quote. We make Cortizo sliding windows to measure and install them across London and the South East, or supply them only to installers and builders.
Last reviewed 2 November 2026
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Key features
- Profile wall thickness of 1.6mm
- Bi-colour systems available
- Finishes: RAL, mottled, textured, wood effect and anodised
- Glazing up to 36mm thick
- Antibacterial powder coating
- Up to 6 sashes on 3 rails
- Max sash weight: 240 kg
- Acoustic insulation up to Rw 40 dB
Specifications
Frequently asked questions
Common questions about Cortizo Aluminium Sliding Windows.
Where do aluminium sliding windows work best?
Anywhere an opening sash would get in the way: over a kitchen worktop, onto a balcony or terrace, or beside a walkway on an apartment block or office. The sashes slide past one another, so nothing swings in or out.
How many sashes can a Cortizo sliding window have?
Two, three, four or six sashes on up to three rails, with windows up to 2,200mm wide by 2,600mm high and sashes up to 240kg.
Are Cortizo sliding windows quiet and weathertight?
The Cortizo 4900 HI reaches acoustic insulation of Rw 40 dB and is tested to Class 4 air permeability, Class 7A water tightness and Class C5 wind resistance.
What U-value does a replacement sliding window need?
In England, a replacement window in an existing home needs a whole-window U-value of 1.4 W/m²K or better, or a Window Energy Rating of band B, under Approved Document L. It depends on the glass and the window size, so we confirm it with the quote.
Can I order Cortizo sliding windows supply-only?
Yes. We supply and fit across London and the South East, or make the windows to your sizes for your own installer to fit.
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