Aluminium Casement Windows

The flush casement window system from Instadoor offers exceptional thermal efficiency, beautiful aesthetics, and the same industry leading 20 year guarantee and 1 week lead time as our aluminium bifold door range.


Thermally Efficient

Durable Powder Coated Finish


Industry-Leading 20 Year Guarantee

High security locking mechanisms

Slim, Lightweight, Durable Aluminium Frames

Metallic or colour coordinated handles

  • Lead time from just 1 week in any standard colour or woodgrain finish, regardless of size


  • 20 Year Comprehensive Guarantee


  • Compliant with Fire Escape Regulations (subject to opening sash size)


  • Available as fixed, top hung, side hung, gable or bay

Engineered to perform and built to last.

Our beautifully crafted and expertly finished aluminium flush casement window system is designed and manufactured in Great Britain. Modernising the design of traditional 19th Century timber windows, our suppliers have created a highly durable and blissfully functional solution which is perfect for the 21st Century.

With unrivalled good looks, security and thermal performance, our aluminium casement windows also offers the added benefits of being maintenance free and manufactured from a premium grade aluminium for long-term reliability.

Manufactured and assembled in a state of the art factory, our casement windows face rigorous quality testing at each stage of the manufacturing process to ensure that every window leaves at a consistently high standard.

Unlike most aluminium products, which have a profile manufacturer and then a 3rd party fabricator, our suppliers have complete control of each product – from sourcing through to manufacturing and delivery –and use high quality components, specifically designed in-house. The emphasis on quality control in all operations enables us to offer an industry leading manufacturer-backed 20 year guarantee for absolute peace of mind. You won't find an aluminium casement window system with an equivalent guarantee for the same price.


Safe and Secure

As well as looking stunning, our casement window range is highly functional and satisfies Building Regulations for emergency exits, restricted openings and marine based dwellings. Side hung and top hung windows can be designed to serve as an emergency exit window by meeting the minimum width and height required to comply with British Building Regulations.

Attention to design is matched by high levels of security, as every window is installed with Yale’s highly renowned and dependable Encloser Lock, which has been tested to PAS 24: 2012 and significantly exceeds the latest security standards for optimum peace of mind.

Low Maintenance

The high grade aluminium our manufacturers use means that expanding and contracting is minimal, so it is guaranteed to offer the right combination of strength and weight to allow the windows to work flawlessly for decades to come. Its impeccable powder coated finish removes the need for periodic painting, maintenance and even protects against scratches and colour fading, ensuring that the windows maintain their good looks.

Inspired by colour

With over 150 different RAL shades and woodgrain finishes to choose from, you can be sure to find a colour that suits your style, no matter how subtle or outrageous it may be. Ranging from bright primary shades through to candy pastels and deeper earthy tones, the extensive colour palette is guaranteed to offer inspiration to homeowners and interior designers alike.

Dual Colour Option

Additionally, with a dual colour option available, it means that the exterior colour can complement the building style while the interior frame can blend in with or contrast your internal colour scheme. Many of the RAL colours also come with the option of offering a matt, satin or gloss finish.

Stay warm in the winter and cool in the summer...

Featuring an advanced triple weather seal that achieved unrivalled weather testing results, our casement window ensures that the elements are kept outside and that energy bills stay low. Fitted as standard with a bespoke thermal break that drastically reduces air flow through the system. The net result is a phenomenally thermally efficient window.

As an option, you can specify your windows with Aerogel for even better thermal insulation. As the world’s best insulator, Aerogel has the lowest thermal conductivity of any known solid material. Composed of up to 99.89% air by volume, the super-insulating silica Aerogel can be used in the thermal break of your windows to considerably limit the heat transfer from one environment to another, allowing an astonishing 0.9 U-Value to be achieved.


Bay Windows

Because all elements of your windows are bespoke, it means the options are vast when specifying a bay. Indicate the quantity of windows, their size, the ones you want to open, the angles between them and the colour scheme, and allow us to create a truly beautiful window that will add an enormous amount of character to your home.

Gable Windows

The gable window can bring the ultimate striking look to a home. Beautifully designed in symmetry and sightlines, a gable window can turn a home into a masterpiece.

It can be installed into even the shallowest of roof pitches, and the mullion sightlines can be aligned with door leaves below for a truly breath-taking architectural solution.

Contact us now for a quote


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