At Liniar we have an absolute commitment to ensuring that each and every one of the creations we produce provides our end users with exceptional advantages over those of our competitors.
Because we have been able to design our range from scratch rather than attempting to improve out-of-date systems, we have been able to consider and factor in future legislation and industry guidelines.
We set our stall out to cut out unnecessary costs and to provide products that are easy to manufacture, easy to install and to include a whole host of benefits and features for the end users.
This is why we firmly believe that our products are the best on the market.
Many old ‘first generation’ uPVC windows relied heavily on steel reinforcement. It was considered essential to securely fix hardware such as hinges and locking mechanisms, in addition to increasing the stiffness of the frame and reducing deflection when subjected to wind gusts.
For many years, this was the accepted make up of a uPVC window – and some are still manufactured this way.
In more recent times energy efficiency became a more prominent topic and the evolution of window products continued with the introduction of uPVC thermal inserts.
These inserts replaced the thermally inefficient steel, occupying the same internal chamber and creating a multi-chambered thermal barrier in the same three-chambered profiles.
Not exactly a giant technological leap but more of a ‘gap filler’ and not without its drawbacks – these thin inserts add very little to the stiffness of the profile, nor do they provide a secure fixing for hardware.
This resulted in many window systems providers having two different offerings – one which is thermally efficient (with thermal inserts) and one suitable for enhanced security (with steel).
Firstly, there were to be no thermal inserts – the multi-chambered effect was designed to be part of the profile, with both the amount of internal webs and their spacing being fine-tuned with Therm software to achieve exceptional thermal performance.
This principal could only be applied to specific profiles within the system, with transoms and mullions remaining steel-reinforced using a steel box section within the central chamber – this provides the rigidity needed within the frame.
Secondly, the issue of secure fixing for hardware was addressed by incorporating a rectangular pocket directly behind areas where fixings would be used, achieving screw pull-out forces rivalling that of 1.2mm thick steel when inserted with a uPVC screw retainer.
The Liniar window system has been independently tested and verified by the British Standards Institute, meeting PAS 24 with reduced steel and BS6375; air and water leakage and wind loading for structural strength.
By making the most efficient use of materials and avoiding the need for expensive triple glazing, the overall cost of manufacturing a window has also been reduced – delivering benefits to fabricators, installers and end users.
Historically, uPVC window systems were fitted with a range of rubber gaskets at the fabrication stage, similar to the method still used on timber and aluminium windows. The resulting permeability of the assembled frame was dependent upon the quality of each seal joint, with many suffering from draughts and wind noise.
The uPVC extrusion process lends itself to the well-established technology of co-extrusion – adhering the gasket onto the frame using a separate extrusion machine during manufacture. This evolutionary step eliminates the time-consuming gasket insertion process and creates a more reliable corner seal at each joint.
Many uPVC window systems make use of co-extruded gaskets, most adapting existing profiles to the process.
Starting from scratch, the Liniar team had no constraints, and spent a significant amount of time developing its patented bubble gasket to outperform all others in speed of fabrication and in permeability – achieving a zero air leakage during independent tests at BSI.
The design of both the gasket and the area behind the gasket is crucial, not only to the permeability of the finished window, but during the welding process where hard lumps can form in the corners of each joint, creaking sealed units.
Liniar’s dual-action gasket performs equally well as a soft dynamic seal on opening sashes as it does as a firm glazing for sealed units, its tolerance-friendly design always ensuring a whistle-free seal inside and out – and no gaps, not even in the corners.
As the quantity and spacing of internal webs reduce thermal transmittance through Liniar frames, the flow is directed towards the path of least resistance. To address this, the Liniar design team introduced a brace of simple but effective ancillary products.
The first is the innovative glazing flipper – this can be clipped onto the short central up-stand within the glazing area, creating a thermal barrier and additional gasket, and sealing the perimeter of any glazed unit – keeping the heat in and moisture out.
The second is the patented thermal dam – introduced to address heat loss at the outer edge of the frame, Liniar’s clip-in thermal dam creates a multi-chambered barrier with optimized leg spacing and is manufactured from recycled material produced during the extrusion ‘start-up’ procedure.
The result is a supremely energy efficient 70mm double glazed product, one capable of achieving a cost-effective A+ Window Energy Rating, or 1.2 W/m²k U-Value and if required a triple glazed 0.85 W/m²k U-Value window.
These innovations have also been included in Liniar’s latest 90mm product range, Zero|90 – which includes the UK’s first uPVC Passivhaus-certified casement window, a Passivhaus-certified tilt & turn window and a full suite including French, bow, bay and mock sash windows as well as residential and French doors. The Zero|90 range was launched in early 2023 and is ready for future building regulations way ahead of the 2025 Future Homes Standard, also including a retro-fit casement window to address the refurbishment market.
Zero|90 windows can achieve U-Values as low as 0.66 W/m²k with standard Argon-filled triple glazing – a feat no other UK uPVC window can yet match.