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Install beautiful, bespoke slimline double glazed windows with Klosen. Whether you’re restoring a period cottage or finishing a modern self-build, our designs sit flush and add that designer finish that standard windows can’t replicate. With more glass and less frame, you can enjoy panoramic views and more natural light. All the windows we supply offer exceptional thermal and acoustic insulation for modern living.
To explore your design options and get one step closer to securing windows you’ll love for years to come, download a brochure or request your free quote.
Slimline double glazed windows are a practical-yet-stylish alternative to traditional PVC or wooden frames. Long-lasting, durable and beautiful, our windows fulfil all the criteria you’re looking for, thanks to our made-to-measure service. We even offer heritage frames to suit more traditional properties.
The barely-there frames enhance views, ensure the maximum amount of natural light enters your property and lifts your property into a contemporary haven.
Built with a polyamide thermal break, these slimline double glazed windows provide good levels of thermal insulation, with low U-values.
We provide a fully bespoke, made-to-measure window service that comes with competitive prices. Double glazing can be 10-20% less than triple glazing, while still offering decent thermal performance.
We offer a 10 year guarantee on all aluminium profiles and 25 years for the powder coating element
Stay warm in the winter and cool in the summer whilst cutting down on energy bills
Our team are flexible throughout the entire process, including the design and installation of windows
Klosen have over 25 years experience working with designers, architects and homeowners
Since 1972, the esteemed Spanish window manufacturer, Cortizo, has been designing and producing slimline double glazed windows.
Expertly installed by Klosen, Cortizo’s premium aluminium systems offer ultra-slim sightlines, as thin as 20 mm for their slimline casement windows. Achieving an impressive glass surface area, these bespoke designs bring more natural light into your home.
They also offer superior energy efficiency and thermal insulation. That’s because Cortizo windows are engineered for the British climate, featuring advanced polyamide thermal breaks that provide U-values as low as 1.0 W/m²K.
As for security, each unit has a multi-point locking system and is PAS 24 certified for total peace of mind.
For sustainability, Cortizo uses materials from waste collection points in Europe, meaning your frames are crafted from recycled aluminium.
Available designs include over 150 RAL colours, including the popular black slimline windows. With a 25-year powder coating guarantee, these bespoke windows offer a durable, low-maintenance solution for both contemporary and heritage properties.
Origin is a leading supplier of high-quality aluminium windows.
Each premium-grade aluminium frame is precisely engineered and subject to strict quality control at Origin’s state-of-the-art facility in Buckinghamshire before being shipped.
Origin’s slimline double glazed windows that we supply include the OW-70 and OW-80 models.
These windows provide security and efficiency, boasting PAS 24 certification, Secured by Design accreditation, and a Nemesis multi-point locking mechanism.
With an extensive palette of 150 frame colours to choose from, as well as bespoke hardware options, you can fully personalise your windows, selecting the perfect final touches.
The thermal performance is high. The 32 mm polyamide thermal break helps achieve low U-values of between 1.2 W/m2K and 1.5 W/m2K.
Combining weather resistance with functional features like night vents, Origin windows provide a secure, energy-efficient upgrade for your property.
Based in Market Deeping in rural Lincolnshire, we cover locations within a 60-mile radius – that includes a pretty broad area across Cambridgeshire, Lincolnshire, and even London.
Popular areas you’ll regularly find our team working on their next project include Peterborough, Bourne, Stamford and Huntingdon.
We bring the same enthusiasm and attention to detail on projects big and small. From working on high-profile projects, including a Grand Designs home and the ABBA Arena in London to upgrading a local home in time for Christmas, our team offer the same level of professionalism with every project.
We’ve installed stunning bespoke windows for homes and businesses for over 25 years.
Below are just some of the reasons customers are glad they chose us:
In summary, we take the stress out of made-to-measure windows. ensuring the design fulfils the brief and future building specifications (think enhanced security and thermal insulation)
The cost of double glazed windows depends on a wide range of factors, including your choice of manufacturer, finishes and whether there are complex requirements for your installation. That being said, double glazing is significantly more affordable than triple glazing while still offering decent thermal performance.
Typically, slimline double glazed windows with aluminium frames can last around 45 years, which is significantly more than uPVC, which has an average life expectancy of 25-35 years.
Double glazed windows have a space between two panes of glass that’s filled with air or an inert gas, such as argon. This provides thermal insulation, and acts as a barrier that reduces the transfer of heat between your interior and exterior.
Yes, slimline double glazed windows reduce the level of condensation thanks to their inclusion of argon glass that keeps the glass panes from getting too cold which can cause moisture to form. While you may still encounter some condensation, this should be significantly less than outdated windows or those with single glazing.
Yes, slimline double glazed windows are considered a suitable option when replacing windows in listed buildings. Planning permission is always required when replacing windows in listed buildings. Here at Klosen, we can support your choice of window to give you the best chance of securing the go-ahead for a modern, thermally-efficient upgrade while maintaining the heritage appearance. Take a look at our slimline heritage windows to see examples of installations we’ve completed for listed buildings.
