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Slimline Aluminium Doors and Windows


Klosen / Slimline

Slimline Sliding Door To Garden
External view of slimline aluminium windows
external view of slimline bi-fold door


With their narrow aluminium frames, slimline aluminium doors and windows are an attractive choice for commercial and residential properties. Bringing excellent thermal and noise insulation levels, you can have a home environment that feels comfortable all year round.

We offer a large range of slimline sliding doors, bifold doors and narrow frame windows that are luxurious in design and elegant in function. Enhance the ground floor of your property with natural light and uninterrupted access to your outdoor spaces.

Klosen are leading slimline aluminium doors and windows installers. We work on commercial and residential installations, and our past work includes a Grand Designs project and the purpose-built ABBA arena.

Customise your designs with a range of opening mechanisms and frame finishes to choose from. Download a brochure to browse your options in more detail.

Get a free quote with us today to get your project started.

Aluminium Bifold Doors

Aluminium bifold doors are installed as a row of floor-to-ceiling doors with large glass panels set in slim frames. These folding glass doors can be pushed to one side to extend your living areas and create a seamless entranceway between your interior and exterior spaces. Discrete bi-folding offers a 95% opening aspect, increasing natural light exposure.

Sliding Doors

Slimline sliding doors blend functionality with aesthetics by optimising your entranceways’ panoramic views. Their streamlined design opens up your interior spaces, with minimal frames. Their design ensures seamless opening and closing, while the durable double or triple glazing and strong aluminium profiles ensures maximum security.

Slimline Aluminium Windows

Slimline aluminium windows offer maximum light and offer a contemporary design that will fit with any home. Not only are the slimline windows stunning in design, but they offer maximum durability and strength.

From casement to traditional sash designs, our windows bring timeless appeal to your property, perfectly matching function and appearance.

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Our Customer Reviews

Great Price & Quick Delivery

This company have been amazing and came to our rescue when another company let us down repeatedly over a period of 4 months during our building work. We got a great price, a quick delivery time and the same product but this time with lovely fitters who knew exactly what they were doing. Now we will will have a warm house for christmas HOORAY !! We went for 3 large sliding doors and the quality of the product is excellent . Many thanks to Audrey Cieran and the team I would recommend highly
- Esther Young


Delighted with the product and the service provided by Klosen. The installation team were excellent and very helpful.
- Sara Hyem

Very Happy

We’ve been very happy with the work Klosen recently completed for us. They installed a variety of windows and sliding doors for us on our new build project. All of the information we requested early on was provided promptly and they were great with our architect. Very happy with the end result and the colour they helped us chose.
- Sarah Munton

Brands We Work With

Designs are selected from leading brands across Europe, including Senior Architectural Systems and Cortizo.

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office with desk and chair and shelving with views over patio area with sliding doors

10 Year Guarantee

We offer a 10 year guarantee on all aluminium profiles and 25 years for the powder coating element

Thermal Efficiency

Stay warm in the winter and cool in the summer whilst cutting down on energy bills

Complete Flexibility

Our team are flexible throughout the entire process, including the design and installation of windows

25+ Years Experience

Klosen have over 25 years experience working with designers, architects and homeowners

Why Choose Us

Klosen has been a trusted name in the industry for over 25 years, providing customers with exceptional bespoke slimline aluminium windows and doors. We specialise in luxury brand doors and windows, combining flair, style and innovation to create contemporary, secure living spaces.

Where We Work

We work across a 60-mile radius from our premises in Lincolnshire. Popular areas we cover include Peterborough, Cambridge, Lincoln and London. From Stamford to Covent Garden, we’re proud to supply luxury doors and windows that enhance properties in urban and rural locations.

Not sure if we operate in your area? Contact our team today.


Are aluminium windows slimmer than uPVC?

Aluminium windows tend to be slimmer and stronger than uPVC. You can have a larger glass surface area due to the strength and support of the frames.

What is the lifespan of aluminium windows?

Aluminium windows and doors typically have a life expectancy of 45 years. This is much longer than uPVC frames which have a life expectancy of only 25-35 years. With Klosen you also receive a 10-year guarantee with your windows and doors.

Are aluminium windows and doors low maintenance?

Yes – aluminium windows and doors require very little maintenance. Make sure you check the guidelines on the best practices for cleaning your frames to ensure a maximum life span.

Get in touch with us today to receive your free quotation!