Cortizo GT70 Aluminium Window

The Cortizo GT70 Tilt & Turn Window delivers professional-grade versatility and high specification for modern homes across Essex and the South East. Designed with inward opening tilt & turn functionality, it offers secure ventilation, easy cleaning access and full-opening capability for a complete connection with the outside. Engineered with deep thermal breaks and slim aluminium profiles, the GT70 achieves U-values as low as 1.2 W/m²K. Ideal for replacing timber or plastic units or for new-build applications, the GT70 offers robust performance, smart style and long-term reliability.

Key Benefits

Tilt & turn operation allowing safe tilt-ventilation and full inward opening for access or egress
Slim aluminium profiles and deep thermal breaks for improved energy efficiency — U-values from 1.2 W/m²K
Maximum sash sizes of up to 1,800 mm wide or high, enabling large window openings
Fully bespoke sizing, configurations and finishes, tailored to your home’s style
Flush-face, minimalist aesthetics suited for both contemporary and traditional properties
High-security multi-point locks and advanced hardware that meet PAS24 standards
Durable, low-maintenance powder-coated aluminium suited to UK weather conditions

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.

How does the tilt & turn function work in the GT70 window?

The GT70 allows the window sash to tilt securely for ventilation or open fully inward for cleaning or emergency egress, giving you safe flexibility and access.

What energy-efficiency can I expect from the GT70?

With double glazing, the CT70 achieves U-values as low as 1.2 W/m²K, helping maintain comfort and reduce energy bills.

Are GT70 windows suitable for large openings?

Yes. They support sash sizes up to 1,800 mm wide or high, enabling expansive glazing and modern light-filled interiors.

Can the GT70 be matched to my property’s style?

Absolutely. Fully bespoke configurations, colours and finishes allow the GT70 to suit both modern and traditional homes seamlessly.

How secure are the GT70 windows?

Very. They feature high-security hardware, multi-point locking systems and meet PAS24 or equivalent standards for intruder resistance.

What maintenance do GT70 windows require?

Minimal. Their premium powder-coated aluminium finish resists corrosion and wear, a simple wipe-down keeps them looking and performing like new.

Are GT70 windows suitable for coastal or exposed locations?

Yes. Their robust aluminium construction and high-quality finishes make them well-suited to challenging environments.

What guarantee is included with GT70 windows from Essex Bi-Fold?

Our GT70 windows are installed by Essex Bi-Fold and come with full manufacturer warranties and our own workmanship guarantee, giving you long-term confidence in performance and finish.

Cortizo GT70 Window