Cortizo Aluminium Casement Windows
Aluminium Casement Windows
Premium aluminium casement windows manufactured in Leeds using Cortizo systems. 2–10 day lead times, fleet delivery, and manufacturer-direct pricing for trade and retail.
Lead Time
2–10 Working Days
Max Frame Size
5,000 × 2,400mm
U-Value
From 1.4 W/m²K
Glazing Range
28–44mm
Design Your Casement Window
Pick a style and size, then tap each pane to choose how it opens: side hung, top hung, tilt & turn or fixed. Add colours, glass and astragal bars, open the sashes, and set it into a brick wall to judge it against a house.
3D view loads as you scrollWe'll send your window details with your enquiry.
On-screen colours are a guide and vary between displays; the RAL code is the reference. Drag sideways on the window to turn it.
For a limited time we will price match any like for like quote!
Get so much more for your money with Mazuli's unbeatable lead times and superior quality.
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Precision-Engineered Aluminium Casement Windows
Mazuli aluminium casement windows combine slim Cortizo profiles with robust espagnolette locking hardware and thermally broken construction — all manufactured in-house at our Leeds factory. Whether you're a trade installer fitting out a new-build housing project or a homeowner upgrading from uPVC, our custom-made windows deliver clean sightlines, excellent thermal performance and a premium architectural finish.
Slim Cortizo sightlines
Clean aluminium profiles for a modern, minimal aesthetic.
Versatile sash options
Side hung, top hung and fixed light configurations.
Thermal performance
Thermally broken profiles with U-values from 1.4 W/m²K.
Large frame sizes
Frames up to 5,000 × 2,400mm for generous openings.
Made at our Leeds factory and delivered across Yorkshire & the UK on our own fleet.
Sash Types & Opening Options
Combine side hung, top hung, tilt & turn and fixed light sashes in any arrangement. Every window is custom-built at our Leeds factory to your exact measurements.
Side Hung
Living areasOpens left or right on vertical hinges for maximum ventilation and easy cleaning. The most popular opening type for living rooms, bedrooms and dining areas. Available as single or double opening sashes within a frame.
Max Sash Width
950mm
Max Sash Height
1,300mm
Max Frame Width
5,000mm
Max Frame Height
2,400mm
Frames up to 2,500mm wide with one or two sashes, 4,500mm with three or four, 5,000mm with five.
Espagnolette locking on all opening sashes · Friction stays on side and top hung · All configurations made to order
7 Stock Colours + Any RAL
Choose from our seven stock colours with the fastest lead times, or specify any RAL colour for a bespoke finish. Dual-colour options — different inside and out — are available at no extra charge on all stock finishes.
White
RAL 9016
Unglazed Lead Time
2–5 days
Glazed Lead Time
6–10 days
Dual-colour (e.g. Anthracite outside / White inside) available on all stock finishes at no extra cost.
Engineered for Energy Efficiency
Our casement windows feature thermally broken Cortizo aluminium profiles with polyamide thermal break technology, exceeding current Building Regulations. Slim frames maximise the glazed area while keeping heat loss to a minimum.
1.4
W/m²K U-value (double)
1.0
W/m²K U-value (triple)
Class 4
Air permeability
28–44mm
Glazing unit range
Exceeds Part L
Our U-values comfortably exceed the Building Regulations Part L requirement of 1.6 W/m²K. Modern thermally broken aluminium now matches uPVC thermal performance while offering slimmer profiles and greater structural strength.
Built to Keep You Safe
Every Mazuli casement window features multi-point espagnolette locking as standard on all opening sashes. Combined with internally beaded glazing and hinge-side security keeps, our windows provide reliable day-to-day security straight out of the factory.
Espagnolette Locking
Multi-point espagnolette locking system engages at multiple points along the sash for robust resistance
Internally Beaded
Glazing beads sit inside the property — glass cannot be removed from the outside
Hinge-Side Keeps
Hinge-side security keeps on all side hung sashes prevent the hinge edge being forced open
Secured by Design
SBD-accredited hardware packages available on request for projects requiring enhanced certification
Peace of Mind
Our locking hardware and glazing methods meet the security expectations of modern residential and commercial projects — without costly upgrades.
Customise Your Casement Windows
Enhance your casement windows with premium hardware options and practical add-ons to suit your project requirements.
Handle Finishes
Available in Black, White, Grey, Chrome, Satin and Gold to complement your chosen window colour.
Friction Stays
High-quality friction stays on all opening sashes for smooth, controlled operation and easy cleaning access.
Trickle Vents
Background ventilation for Part F compliance without compromising security or clean frame lines.
Georgian Bars
Internal, external or duplex Georgian bar options for a traditional glazing pattern on a modern aluminium frame.
Cill Options
Cills available in 90mm, 150mm, 180mm and 230mm depths with 20mm and 38mm head extensions.
Lead Times
Mazuli's in-house fleet of delivery vehicles mean you receive your product on time every time
Unglazed
Standard Colours (Subject to Order Quantity)
Glazed
Standard Colours (Subject to Order Quantity)
RAL Colours
Woodgrain Colours
Aluminium Windows — popular delivery areas
Made in our Leeds factory in 2–10 working days and delivered on our own fleet nationwide. Pick your area for local details.
BasingstokeAluminium WindowsHampshire
BristolAluminium WindowsBristol
CardiffAluminium WindowsSouth Glamorgan
DerbyAluminium WindowsDerbyshire
DundeeAluminium WindowsAngus
East LondonAluminium WindowsGreater London
EdinburghAluminium WindowsMidlothian
IpswichAluminium WindowsSuffolk
ManchesterAluminium WindowsGreater Manchester
NorwichAluminium WindowsNorfolk
ReadingAluminium WindowsBerkshire
South LondonAluminium WindowsGreater London
SouthamptonAluminium WindowsHampshire
WarringtonAluminium WindowsCheshire
WatfordAluminium WindowsHertfordshire
Photos: Basingstoke by Lewis Hulbert, CC BY-SA 3.0 · Bristol by Chris Lathom-Sharp, CC BY-SA 4.0 · Cardiff by Chris Morgan, CC BY-SA 2.0 · Dundee by Colin Smith, CC BY-SA 2.0 · East London by Hjamesberglen, CC BY-SA 4.0 · Edinburgh by Andrew Colin, CC BY 2.0 · Ipswich by Velvet, CC BY-SA 3.0 · Manchester by David Dixon, CC BY-SA 2.0 · Norwich by Tanya Dedyukhina, CC BY 3.0 · Reading by Smuconlaw., CC BY-SA 4.0 · South London by Robert Dimov, CC BY-SA 3.0 · Southampton by Alex Wright, CC BY-SA 3.0 · Warrington by Reading Tom, CC BY 2.0 · Watford, CC BY-SA 2.0
Frequently Asked Questions
Everything you need to know about our casement windows — pricing, sizes, lead times and more.
Ready to Get Started?
Whether you're a trade installer or a homeowner, we have the right solution for your casement windows project.
Trade Installers
Volume pricing, dedicated account management, and the UK's fastest lead times. Join hundreds of trade installers who trust Mazuli.
Homeowners
Factory-direct quality at prices that undercut national brands. Get a personalised quote with no hidden extras — it's as easy as sending us your measurements.
Known for being one of the leading manufacturers of aluminium systems for the architecture and industry sectors in Europe.
Casement Windows technical documents
Technical sheets, configuration and installation guides and the product brochure are sent on request, so you get the current version for your specification.
- Casement Windows Technical Sheet
- Configuration Guide
- Installation Guide
- Product Brochure
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