Why fabricators love uPVC Liniar doors

Early in 2007, Liniar’s former MD Roger Hartshorn sat down with a trusted team of designers and a blank sheet of paper. With a wealth of experience between them they set about creating a totally new profile design. They knew what worked and, more importantly, what didn’t.

While other companies could only attempt to modify and improve the old systems they already had, Liniar had the luxury of working without limitation, removing past faults and adding in elements that they knew would improve performance, plus making the fabrication process simpler and quicker.

It was Liniar’s mission to design a unique system that combined security with energy efficiency while offering fabricators the additional benefit of saving costs through faster production times and reduced steel.

Simply secure

The team identified that the weakest area is generally where the hardware is located, at the front of the main frame. By adding a small pocket behind these areas they could insert a small piece of uPVC.

When using the correct screw, through what is effectively three layers of uPVC, they managed to enforce the profile with the same pull-out strength as if it were going into 1.2mm of thick steel.

With no reinforcing in the outer frame or the sash this was independently tested by BSI to PAS 24 standards.

Gaskets had long been a bone of contention in the industry. The two different styles of gasket, glazing and weather seal, had been inserted by hand in the past into a gasket groove in the profile at the fabrication stage.

Once co-extruded gaskets were introduced to save time, this created a problem. One type of gasket was attempting to do two different jobs and was succeeding at neither and causing serious fabrication issues with hard points in the corners.

For a weather seal to work effectively it has to be able to compress to zero, while a glazing gasket should only compress so far before letting the bead take over. If this isn’t the case then the glass will move within the frame.

A glazing stop was used to prevent this but, if one gasket had been extruded fractionally larger than the other, which is often the case, it would only seal on one side, resulting in a draughty, whistling window.

Eureka moment

Liniar’s ‘eureka moment’ came when they switched the pip of the gasket from the outside to the inside of the profile. This meant that the gaskets being used as weather seals would have 8mm cover on the profiles, while the simple bubble seal will carry on compressing to nothing.

So no matter what size the gasket is extruded at they will always find the nominal compression and the glazing gasket will get more cover with the unit.

Did this mean that a gasket groove was no longer needed?

The major problem with traditional gasket grooves is caused when a gasket was positioned over the top it led to hard lumps forming in the corners during the welding process. It was a lengthy and time consuming process for fabricators to clean these out.

The Liniar system was designed with this in mind. The back of the profile was hollowed so that any build-up of material was pushed into the groove. This meant that there were no issues at all with the corners, making the cleaning process far more efficient and removing the need for expensive machinery – yet another huge saving for fabricators.


Another big criticism of the industry was the lack of consideration given to drainage. To combat this, Liniar designed a unique yoke within its system. This clever little addition, combined with drain slots, allows the water to flow to the outside.

Other systems are designed to hit the wall at 45°, creating burrs and swarf that can cause the water to dam up over time unless cleaned out. This is another way that Liniar’s profile helps fabricators to speed up operations.

Another slick innovation with the yokes is that one is 3mm deeper than the other one. This miniscule difference means that if a fabricator uses a hand drain slot machine then the settings are identical whichever way the profile is, allowing for it to be symmetrically drained and removing the need for settings to be constantly altered.

Bigger mainframe

A common problem with residential doors is that quite often, the depth of the plaster line and the skirting board means that the door can’t be opened fully to 90°. The answer to this is usually to use a frame extension, but this means extra work and extra cost.

Because Liniar’s mainframes are available at 77mm this means that extensions are required far less, saving fabricators time and money.

Another disadvantage of a door frame extension is that one is usually needed on both sides to prevent an offset appearance. Making it look symmetrical means that the opening will be narrowed.

Low thresholds

Liniar has two low thresholds, 15mm and 25mm. Both of these are Part M compliant for wheelchair access. The thresholds passes underneath the mainframe and is connected together quickly and simply. Everything is square cut, again making it extremely fabricator friendly to create a low threshold uPVC door.

Continued development

Since its launch, Liniar’s philosophy to create and innovate has continued relentlessly with a long line of new designs, products and ranges taking the industry by storm – including the first bespoke uPVC bi-folding door, since re-launched with the amazing ModLok technology.

Fabricate the range of Liniar doors

Liniar Web2Print Services Designed by You


Liniar had the luxury of working without limitation, removing past faults improving performance, making the fabrication process simpler and quicker.

Clean Corners

Clean corners

With Liniar windows, the cleaning process is far more efficient, with no hard lumps forming during welding, there is no need for expensive machinery.

Bubble Gasket

Fantastic gasket

Liniar's patented co-extruded bubble gasket eliminates the the time-consuming gasket insertion process and creates a more reliable seal at each joint.

Bigger Mainframes

Bigger mainframes

Because Liniar’s mainframes are available at 77mm this means that extensions are required far less, saving fabricators time and money.

Low Thresholds

Low thresholds

Liniar has a number of Part M compliant low thresholds. The thresholds passes underneath the mainframe and is connected together quickly and simply.

Customer Feedback

Customer feedback

Liniar works closely with fabricators, taking into account feedback to continuously improve and innovate our range, making it quicker and more cost effective to fabricate.

The Liniar product range

QNX Passive House Secured By Design Corgi Fenestration BSI12608 PAS24 Security ISO 14001 ISO 9001 bhhpa Bali NCC Queens Awards Sustainable Midlands Supporter

Enter Your Postcode To Get Directions!

View Full Map, Share & Print
Contact Us