As published in Glass & Glazing Products Magazine – December 2016

Chris Alderson, Managing Director for Edgetech UK, talks about the continued trend for bi-folds and wide span sliding doors and the impact they have for insulated glass unit manufacturers.

What the trend for bi-folds means for insulated glass unit manufacturers

Talk to anyone in the industry, and they will tell you that bi-folds and wide span sliding doors remain the biggest growth area. The latest Palmer Report predicts that this will continue to increase, and that aluminium doors are growing faster than PVCu – although both are up.

When we talk about bi-fold and wide span doors, it’s easy to think only about the frames. Systems companies promote the extra height and width they can squeeze out of each leaf, and bigger is better.

Door manufacturers have been looking at ways to improve the thermal efficiency of bi-fold and wide span doors. While Building Regulations require a minimum U-value of 1.8 W/m2K for doors, we are seeing more claims of 1.6 and even 1.4 and it’s the glass units that play a big part in delivering thermal efficiency.

Triple glazed units can be used to increase energy performance, but the extra weight of the glass can be problematic in these oversized units. A 6mm pane of glass in a 1.8m x 2.1m door could add up to eight and a half stone. The alternative is to choose better performing ‘clever doubles’ using warm edge technology. Using double rather than triple glazed units makes door leafs lighter so they’re easier to handle and makes them the first choice for most fabricators and installers of bi-folds and wide span doors.

Weight is an important consideration during the manufacturing process too. Automation reduces manual handling, which is a big benefit for heavier insulated glass units. It also maximises speed and efficiency in production.

However, it’s not just making standard glass units bigger, these oversized IGUs can’t be treated the same as smaller ones. To start with there’s the issue of deflection. A large rigid spacer bar frame is likely to bend and even a small variance could cause the spacer bar to protrude into the sightline. Super Spacer® is designed not to move, the acrylic seal on either side of the bar creates a strong bond with the glass which keeps it in place during manufacture. And Super Spacer references the glass edge as the unit is made so it is perfectly level.

This bond counteracts another possible issue with IGUs. Glass units are subject to cavity expansion and contraction as temperatures rise and fall, and this is exaggerated in larger units. Super Spacer’s flexibility means it can allow for movement which prevents the glass cracking under stress, whilst maintaining its exceptionally strong adhesion to the glass. It does not set under compression, so it maintains its structural integrity in pressure glazing situations and will always look to return to its original shape and dimension.

Customers tell us that large glass units are now making up a bigger percentage of their production. As well as supplying the right products, Edgetech has the technical expertise to support insulated glass unit manufacturers who are facing this change.

As you would expect from the driving force for energy efficient glazing, the Edgetech range of warm edge spacers includes a product that was developed as the ideal system for manufacturing larger units. Super Spacer Premium Plus has led the way in commercial structural glazing. It has been proven in IGUs of up to 15 metres in length without issues of movement or deflection and comes with an industry best 40-year guarantee.

If, as predicted, numbers of bi-fold and wide span sliding doors continue to grow, the importance of delivering large, high quality, energy efficient glazed units will become even more important. Super Spacer Premium Plus offers IGU manufacturers, fabricators and installers complete peace of mind.

Proven system

Royal Alexandra Hospital

Super Spacer Premium Plus is not a new product. It was actually the original version of Super Spacer introduced in 1985 and has shown exceptional performance for large glass units. It’s been used continuously over the last 32 years and has been fitted in massive projects throughout the world.

In 1992, 25 years ago, it was chosen for a new glass atrium of the Royal Alexandra Hospital in Edmonton, Canada. The city often experiences heavy snowfall, severe storms and temperatures as low as -40 degrees Celsius, but inside the humidity is kept at 50 percent to reduce the risk of infection.

For the project, more than 13,000 metres of Super Spacer were processed and to date no glass unit has had to be exchanged, nor any condensation formed on the windows. Super Spacer was specified for another development at the hospital in 2005.

You can read the full project case study here: Royal Alexandra Hospital Case Study