Cortizo Windows
Cortizo Cor 70 Hidden Sash: tilt-and-turn / casement aluminium window on a 70 mm thermally broken frame. The 'hidden sash' detail conceals the opening sash within the frame depth, so a closed window reads as a single fixed glass panel. Uw from 1.0 W/m²K, 66mm visible section, Class 4 air permeability (BS EN 12207, the maximum), PAS 24 certified. Vitrum Solutions fabricates the Cortizo windows range in our own Uxbridge workshop and installs it across Buckinghamshire, Berkshire, Oxfordshire, Surrey and Hampshire.
Cor 70 Hidden Sash Specifications
System
Cor 70 Hidden Sash
Frame Depth
70 mm thermally broken
Thermal
Uw from 1.0 W/m²K
Air Permeability
Class 4 (BS EN 12207, the maximum)
Why Cor 70 Hidden Sash
Hidden Sash — concealed sash detail
The Cor 70 Hidden Sash hides the opening sash within the frame depth so a closed casement reads as a single fixed glass panel — there's no visible step where the sash meets the frame, just an unbroken glass plane and a slim outer frame. The architectural detail is most noticeable from outside, where the elevation reads cleaner than a standard casement window.
Tilt-and-turn / casement function
Two opening modes from a single handle position: tilt the top of the sash inwards for secure ventilation (the window is open but not hinge-clear so it can't be reached); full turn for cleaning the outside glass safely from inside (so the window is its own access point on upper floors). Used most often on first-and-above floor casements where escape access matters or where outward-projection is restricted by walkway / planting / boundary.
Uw from 1.0 W/m²K
Cortizo's thermally broken Cor 70 Hidden Sash, paired with Class 4 air permeability (BS EN 12207, the maximum air-tightness rating), reaches Uw from 1.0 W/m²K. Used on premium contemporary new builds and low-energy refurbishments where the window's thermal performance directly affects the building envelope's overall rating.
70 mm thermally broken frame
Polyamide thermal break separates the cold outside metal from the warm inside metal across the 70 mm frame depth. Multi-chamber profile keeps the structure dimensionally stable across UK seasonal temperature swings. Steel-reinforced frame internals on opening profiles for long-term frame straightness.
PAS 24 + Class 4 air permeability
All Cor 70 Hidden Sash opening profiles are PAS 24 certified with multi-point shootbolt locking, hidden hinges, internally-beaded glazing and laminated inner glass options. Tested to BS EN 12207 Class 4 air permeability — the maximum air-tightness rating, meaningfully reducing draughts and heat loss versus standard aluminium frames.
Aluminium Windows on Our Range
Cor 70 Hidden Sash feeds into our two aluminium window product pages depending on whether the architectural detail wanted is the standard casement frame or the slim flush-casement variant.
Get a free quote for Cortizo Cor 70 Hidden Sash Windows
Free no-obligation written quote. Fast response times. FENSA registered with a 10-year CPA insurance-backed guarantee. Serving Buckinghamshire, Berkshire, Oxfordshire, Surrey, Hampshire, Hertfordshire & West London.
Other Cortizo Systems
Bifolds, sliders, lift-and-slide and aluminium front doors are covered by purpose-built Cortizo profile systems — all fabricated in our own workshop and fitted by Vitrum Solutions.
Cortizo Bifold
Bi-Fold and Bi-fold Plus Door (slim premium 110 mm reduced central junction).
View Bifold →Cortizo Sliding
Cor Vision Sliding (20mm central junction) and Cor Vision Plus Sliding (25mm central junction).
View Sliding →Cortizo Lift-and-Slide
The lift-and-slide version of the 4700 Sliding Patio.
View Lift-and-Slide →Cortizo Millennium Plus
70 / 80 mm aluminium entrance door range with PAS 24 multi-point locking.
View Millennium Plus →Cortizo Windows — Frequently Asked Questions
Do you fabricate Cortizo windows or just install them?
Both. Vitrum Solutions is a Cortizo manufacturer, fabricator and installer — we fabricate Cortizo windows in our own Uxbridge workshop, cutting, machining and assembling Cortizo profiles into finished windows, then survey, deliver and fit them with our own team. That means one company and one point of accountability from profile to finished installation, rather than buying made-up units from a third party. FENSA registered, with a 10-year CPA insurance-backed guarantee.
What is Cortizo Cor 70 Hidden Sash?
Cor 70 Hidden Sash is Cortizo's tilt-and-turn / casement aluminium window system on a 70 mm thermally broken frame. The 'hidden sash' detail means the opening sash sits concealed within the frame depth, so a closed window reads as a single fixed glass panel without the visible step where a standard casement sash meets the frame. Used on premium contemporary projects where the architectural priority is the cleanest possible elevation.
What is a tilt-and-turn window?
Tilt-and-turn gives two opening modes from a single handle. Turning the handle 90° lets the top of the sash tilt inwards for secure ventilation — the window is open but not hinge-clear so it can't be reached. Turning the handle 180° unlocks full hinge function so the sash opens fully — useful for cleaning the outside glass from inside (relevant on upper floors) or for fire-escape access. The function is standard on Cor 70 Hidden Sash.
What U-values do Cortizo Cor 70 windows achieve?
Cor 70 Hidden Sash delivers excellent whole-window U-values when paired with the right glazing spec. With double-glazed Low-E units the whole-window Uw lands in the 1.2-1.4 W/m²K range, comfortably exceeding Approved Document L's 1.4 W/m²K maximum. The system reaches Uw from 1.0 W/m²K. Specific Uw is calculated per opening at quote stage.
How does Cor 70 Hidden Sash compare to Schuco AWS aluminium windows?
Both are premium aluminium casement systems on a 70 mm frame. Cortizo Cor 70 Hidden Sash's distinguishing feature is the concealed-sash detail — a closed casement reads as a single fixed glass panel. Schuco's AWS family includes AWS 70.HI (workhorse with 105 mm outward / 117 mm inward sightline + 52 mm glazing capacity), AWS 70 SC Slimline (architectural slim 63.5 mm sightline) and AWS 70 Tilt-and-Turn (inward-opening). Where the brief is open, we walk you through both at the survey stage. Side-by-side: Cortizo vs Schuco: Which Aluminium System is Better?.
Are Cortizo aluminium windows energy efficient?
Yes. Cortizo's thermally broken Cor 70 Hidden Sash paired with Class 4 air permeability (BS EN 12207, the maximum) reaches Uw from 1.0 W/m²K. Even with standard double-glazing the whole-window Uw comfortably exceeds Approved Document L's 1.4 W/m²K maximum for replacement windows. The 70 mm thermal break separates the cold outside metal from the warm inside metal so condensation on the inside frame is minimised.
Can I get Cor 70 windows in any RAL colour?
Yes. Full RAL palette plus anodised finishes (champagne, bronze, dark grey, black) and dual-colour configurations. The Cor 70 Hidden Sash detail conceals the opening sash behind the outer frame, so on the elevation the window reads as a single fixed pane regardless of colour. Bold anthracite, bronze and matte black finishes are particularly common on this system because nothing interrupts the colour band. The finish bonds to the aluminium substrate (powder-coat or anodise), not to a foil, so it does not fade or peel across decades.
Other Systems We Install
We supply and fit the full premium-brand glazing range across the Home Counties. Compare specifications and pricing across our brand hubs.
Schuco
German aluminium systems
Visit Schuco hub→Origin
Premium aluminium, up to 20-year guarantee on parts
Visit Origin hub→Rehau
A-rated uPVC profiles
Visit Rehau hub→Palladio
Irish monocoque composite doors
Visit Palladio hub→Gerda
Polish RC2 steel security doors, RC3 upgrade on Optima/Thermo Premium
Visit Gerda hub→Korniche
UK-made aluminium roof lanterns
Visit Korniche hub→SteelR
UK-made RC4 bespoke steel front doors
Visit SteelR hub→Quote for Cortizo windows?
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