How we designed and built the floating glass box at the Showroom
The Invisio SkyBox floating glass box is a key feature of the £1.5M IQ Glass showroom refurbishment which is now open to visitors.
This bespoke structural glass feature is fully glazed and cantilevered from the first floor office creating a floating all glass space. With a frameless structural glass floor, ceiling and four glass walls the structure is almost completely transparent, offering architect’s and their clients an idea of what is possible from structural glass design.
When we sat down to brainstorm ideas for our new glass showroom the whole team were really keen on showcasing the technical capabilities of structural glazing. We wanted to show architects and their clients what you could achieve from frameless glazing, how strong glass was and how versatile.
The floating glass box was the brainchild of our installations director who wanted to create something no one had seen before. The idea was to create an all-glass box that seemed to float in the air with no visible supports or steel structure.
We started by speaking to our glass suppliers to determine what restrictions we had in terms of feasibility for the glass structure.
What was the thickest pane of glass they could manufacture? What was the largest unit they could manufacture?
With this information we put together some simple 3D designs for the floating glazed box that we could use as the basis for our calculations and designs.
Design of the Steel Structure
A simple steel structure was desired for the glass box – we wanted something that was minimal and unobtrusive. The frameless glass was to be the feature element of the construction and the steel had to be designed in a way that was unobtrusive.
We worked with an external 3rd party structural engineer to carry out all required calculations to determine how the frameless glass structure would behave and the required specification to support the glass box.
Once the study was completed, we were able to specify the supporting structure. We then worked with a specialist steel fabricator to manufacture and install the steel structure as designed.
Design of the Glass Structure
Once the steel supports were designed, we were able to design the floating glass structure. Thanks to our expertise in structural glazing design we were able to design this glass structure in house with our design managers and installation director.
A few different options were designed and modeled using 3D design software. We were focusing on creating a frameless glass structure that could take all the necessary loads, be frameless and was efficient to manufacture and install.
The final chosen design was then put through a 3rd party check and simulation by a specialist consultant who specialises in glass engineering to ensure our calculations were correct and accurate.
The Final Design and Specification
The steel design and floating glass structure design were combined to create the overall design for the floating glass box. The glass simulation and calculations determined the glass thicknesses and specifications we required to achieve the frameless design we wanted with the accepted deflection and movement.
The glass floor of the floating glass box was being designed to support a uniform 2.5kPa live load in both pre and post break conditions as a minimum. The glass floor calculations showed us that we had two main options:
- 4 layers of 10mm TXD glass that were laminated together with a strengthening ionoplast interlayer
- 4 layers of 12mm TXD glass that were laminated together with a standard PVB interlayer.
Both options exceeded the required uniform live load with up to 4.7kPa for option 1 and 3.8kPa for option 2. We decided to opt for 4 layers of 10mm TXD with ionoplast interlayers in order to achieve a higher strength glass specification.
The specification of the glass units within the floating glazed box were very specific and highly bespoke. There were limited glass suppliers who could make the required glass and we worked with one of our regular glazing suppliers to design and manufacture the required glass units.
Our key considerations were to achieve glass units that were of the exact specification required as well as having a high glass clarity. We worked with the glass supplier to ensure the glass was made to a high quality and standard.
In addition, the glass floor had a bespoke fritted pattern on the external edges to hide the steel structure below. This had to be applied to the glass using a digital printing method which was difficult to do due to the size and thickness of the glass required.
Glass Box Installation
We carried out the installation of the floating glass box ourselves with one of highly experienced installation teams.
The glass units were heavy and large, and the installation was inside which limited our access and machinery options. The installation and lifting plan was determined by our installations director in conjunction with the crane hire company.
A combination of Hiab crane, chain pulleys, vacuum lifters and manpower were used to get the glass units into the building, up to the first floor and into position.
Due to the box’s location within the building, the Hiab crane had to reach through the doorway to lift the glass units. The ceiling height internally was not high enough to enable the Hiab to lift the glass fully in place. Instead, we had to create a series of pulleys from the roof that allowed the glass to be lifted up and into place.
Another complication was the sequence in which the glass units had to be lifted and fitted.
The glass walls for the floating glass box were designed to sit on top of the glass floor panes so had to be installed after the floor. However, once the floor panes were in there would have been no space to lift the glass walls…
In the end we lifted the glass walls up and created a temporary structure for them just off the line of installation. This allowed us to then lift the glass floor panes into place using the Hiab crane and then manually shift the glass walls into place on top using chain pulleys to create the floating glass box.
Due to the tight installation zone we had to lift very carefully and slowly. If one edge or corner of the glass unit had caught on the protruding steel then the units would have broken putting us back to the beginning.
The glass end went in next followed by the smaller glass panels for the roof which surrounded the air conditioning unit.
All glass was temporarily secured and structural silicone applied.
The end glass pane of the floating glass box is completely held in place with structural silicone, really showcasing the strength of this underestimated building material.
The End Result
The Invisio floating glass box is one of the key focal points of the new IQ Glass showroom in Amersham and is one of the biggest talking points for visitors who come. Everyone loves to have their photo taken in the floating glass box – making it look like they are floating in mid air.
Come and see the space for yourself by booking your visit to the IQ Glass Showroom in Amersham. We are happy to arrange general visits for architects or specifiers wanting to see the space. We can also organise CPD seminar sessions at Sky House for those wanting to make an event of the visit.
Click here to book your visit or contact the team on 01494 722 880.
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