Cortizo GW70 Aluminium Window

The Cortizo GW70 Aluminium Window combines refined aesthetics with outstanding performance, providing a high-quality glazing solution for modern homes and commercial spaces. Designed specifically for the UK market, the GW70 is available in both flush and standard casement variants, offering flexibility for any style of property.

With slim aluminium frames, deep thermal breaks, and advanced weather performance, the GW70 achieves impressive U-values from 1.0 W/m2K. Supporting large sash sizes of up to 1,800 mm wide or high, this system delivers clean sightlines, excellent insulation, and durable operation. Perfect for new builds, extensions, or replacing tired timber and uPVC units, the GW70 combines sleek design with long-lasting quality.

Key Benefits

Available in flush or standard casement variants to complement any architectural style
Slim aluminium profiles maximise natural light and provide a clean, modern look
Deep thermal breaks ensure outstanding insulation, achieving U-values from 1.0 W/m2K
Compatible with double or triple glazing for enhanced efficiency and noise reduction
Supports sash sizes up to 1,800 mm wide or high, among the largest in its class
Smooth, precision-engineered hinges and hardware for effortless opening and closing
Suitable for residential and light commercial applications
Durable, powder-coated aluminium for minimal maintenance and long-term reliability

Why Choose Essex Bi-Fold?

30 years Experience

Over 30 years of experience and 2,500+ successful installations across Essex and the South East

Origin Premium Partner

Recognised Origin Premium Partner – trusted for excellence in installation and service.

Extensive range

Extensive window range: bi-fold, casement, gable, picture, French, and bay styles to suit any property.

Essex Showroom

Dedicated Essex showroom where you can view and test our full range of aluminium windows

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Jeanette White

"The Bi-fold doors are amazing. The showroom has a few full set-ups which allowed me to have a good look and try it out before deciding. "

Raymond Law

"We visited Essex Bi-Fold doors and met with Clive and were impressed with there showroom and expertise. The doors we ordered look great, and the quality is excellent. "

Lester Wadden

"Essex Bi-fold Replaced our two old Kitchen roof windows with new Korniche roof lanterns. The whole experience, from initial enquiry to completion of installation, was excellent. The design of the new windows is so much more efficient, allowing more light into the kitchen."

Vicky Knight

"Wonderful experience from start to finish. We purchased Origin Bi-folds from Essex Bi-Folds August 2025. Easy to purchase, great showroom with lots of options, good price, amazing quality. "

The Bootlegger

"Great service and communication. OS-29 sliding door went in without issues. We’re really glad we found Essex Bi Fold as they’ve been on point. Loving the door quality and look. Feels very strong, door glides open with ease. 10/10."

Karen Scarsbrook

"Highly recommend this company. Everyone we dealt with from Lee in the office, his manager and the installers were extremely nice and super helpful - going the extra mile to get the finish we desired. "

Paul Marsh

"Absolutely fantastic team Clive Lee and the guys couldn't do enough for you. The difference its made to our lives is insurmountable."

Recent Projects

Real projects, real results - crafted with precision and care

Explore our latest projects featuring bi-fold doors, sliding doors, entrance doors, and windows - transforming homes with light, space, and modern design, all crafted with precision and care.

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A Modern Touch for a Countryside Classic

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Open-Plan Garden Transformation

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Beaumont Hall Barns Restoration

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High Spec Essex Development

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Chelmsford Conservatory Transformation

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Light-Filled Kitchen Extension

Questions? We’re Here to Help

Find answers about our services - or ask us anything you don’t see.

What makes the Cortizo GW70 different from other aluminium windows?

The GW70 has been purpose-designed for the UK market, featuring slim sightlines, deep thermal breaks, and advanced glazing options to combine contemporary style with superior energy performance.

How energy efficient are GW70 windows?

Highly efficient, the system achieves U-values from from 1.0 W/m2K, helping reduce energy bills while keeping your home comfortable all year round.

Can I choose between flush and standard designs?

Yes. The GW70 is available in both flush-fit and standard casement profiles, allowing you to select the look that best suits your home’s style and character.

What sizes can GW70 windows be made in?

Each window is fully bespoke, with maximum sash sizes of 1,800 mm wide or high, providing greater flexibility and larger glazed areas than most alternatives.

Are GW70 windows suitable for both new and replacement projects?

Absolutely. They’re ideal for new builds, extensions, or replacing older timber or uPVC frames, offering a premium upgrade in both appearance and performance.

Can I upgrade to triple glazing?

Yes, the system is fully compatible with triple glazing for enhanced insulation and acoustic control.

How much maintenance do aluminium GW70 windows need?

Very little. The powder-coated finish is durable, weather-resistant, and easy to clean — a simple wipe with a soft cloth keeps them looking like new.

What warranty comes with the Cortizo GW70?

Every GW70 window installed by Essex Bi-Fold is backed by a 10-year manufacturer’s warranty and our 5-year workmanship guarantee, giving you total peace of mind.

Cortizo GW70 Window