April 27, 2022

The Construction of the Double Height Vertical Sash Window and minimal windows 4+ Opening

Written by Rebecca Clayton

double height glass doors with vertical sash window

Discover the process behind the construction of the oversized sliding façade at the IQ Glass glazing showroom.  

When the new IQ Glass showroom was redesigned, a double height glass façade stretching 6.5 metres tall was designed as part of the exterior design. The frameless structural glass façade sits next to an opening where a vertical sash window and an automated single pane sliding door have been installed, both reaching over 6 metres tall.  

double height glass doors with slim aluminium profiles

The oversized glazing solutions were designed to showcase what bespoke engineered glazing can achieve when specified on a large scale, with the technical team of designers at IQ having the ability to adapt the solutions to create innovative glazing designs to suit specific project requirements.

To reach the large sizes at the glazing showroom, the vertical sash window was designed on a completely bespoke basis and alterations were made to accommodate the weight of the oversized panes.  

Due to the height of the double height glass doors, IQ adapted the profiles within the moving panes to include reinforced interlocks, using a steel rod to reinforce the interlocking profiles to enhance the stability without altering the appearance. The vertical sash window was designed with a U profile to hide the frame inside it and this U profile aligns with the reinforced interlocker to keep the sightlines as slim as possible. The glass specification for the vertical sash window was 8/14/8, with an argon gas cavity filling.  

vertical sliding sash window and double height glass doors

The minimal windows automated slider required a larger spacer bar than a typical specification - this was needed due to the size of the pane, to accommodate the deflection of the glass and prevent Newton rings from occurring.

The argon gas cavity within the insulated glass unit was 22mm and the minimal windows 4+ profile was utilised for the installation, to accommodate the depth of the glass unit. The specification for the sliding glass door was 15/22/10 with a low E coating on the glass surface for enhanced clarity.  

Both double height glass doors are complete with a flush threshold detail, merging indoor and outdoor areas when the glass door solutions are open. The flush threshold is perfect for creating step free travel between the two environments and is even safe to drive over, having been used for luxury car garages previously.  

construction of double height glass doors with flush threshold detail

The automation of both glazing solutions was designed on a bespoke basis, with upgraded motor systems to accommodate the weight of the double height sliding glass door that was programmed in a way which allowed the initial movement of the 1.4 tonne glass. The vertical sash window uses high output automation with a pre-programmed slow movement at the start and finish to ensure the oversized systems do not get damaged when opening or closing. Both sliding systems are operated via a deadman switch, with soft closing mechanisms to protect the exposed profiles when in use.  

The installation was extremely complicated and the vertical sliding panes had to be temporarily lifted into place, allowing the cables to be threaded before fixing the panes in place. Using 3 cables on each side that run through the profile and connect to a pulley system, the cables had to be adjusted and the placement of the panes tested before they could be secured into place.

Once the cables were adjusted correctly for the counterweighted technology, each pane could be securely fitted in place. The solution included a number of back up tension rods which would take the weight of the glass in the unlikely event the primary tension rods failed.

Each of the panes within the vertical sash window were bonded on 3 sides on the stillage, prior to installation. The last profile (at the bottom of the glass) was bonded after installation due to the size of the glass, it was too heavy to be spun around with a crane.  

double height glass door construction in glazing showroom Amersham

The main challenge of this installation at the glazing showroom was the size of the systems, which meant deflection had to be carefully considered. This was achieved using the steel rods inside the interlocker sections of the profiles, giving the system extra weight and security to accommodate the deflection and create a safe oversized glazing installation.

The team of installers are used to installing glazing solutions on a large scale, with experience in adjusting the installation process to suit these bespoke engineered solutions.  

To see the impressive double height glass doors in action, book your showroom visit today. The team are on hand to answer any technical questions and assist with specification.  


"I was amazed by the Sky House and showroom. Having worked in the Luxury property market for 9 years – I was blown away by the quality, innovation and creative design of the Sky House, reception and range of tailored glazing solutions that they can offer. I can see why they are leaders in their field. “  - Russell Rhys-Davies, Marketing Director at Abode2