TECHNICAL ADVICE
Bonded vs Beaded Glazing
What is bonded glazing?
Bonded glazing is a strong chemical connection between a glass unit and a structure, frame or other unit of glass.
It is most often used in frameless or very minimal glass installations. The process of bonding the glass to structures minimises the use of additional bits of frame meaning that the installation has less structure.
Glass that is bonded always must have a silicone seal to the double or triple glazed unit in order for the bonding to be successful.
What is beaded glazing?
Beaded glazing is a more traditional form of fixing glass into framing systems. The glass unit is placed into the frame and then a glazing bead is clipped into the frame, securing the glass unit in place.
The bead can be made from a variety of materials including vinyl, wood, aluminium and uPVC. Although in most cases the glazing bead is in the same material as the frame.
Bonded vs Beaded
Both bonded glass and beaded glass installations have their place in construction. There will be many factors to consider when looking to choose between a bonded and beaded system.
Design
Bonded glass is most often used in aluminium windows and doors with a very minimal frame design. By bonding the glass into the frame you reduce the amount of frame in the opening and therefore reduce the sightlines.
Our Sieger Slim sliding door system is a bonded system. This means that we need no glazing bead to hold the glass in place and the sightlines are a very minimal 20mm.
Due to bonded glazing having slimmer sightlines, it may seem more suited for a contemporary aesthetic, however sightlines are not the only reason that bonded glass could be used on a project.
Security
An advantage of bonded glazing is that it offers a more secure glass fixing technique. The glass unit is chemically adhered to the outer frame, meaning that it simply cannot be removed.
Beaded glazing must be done from the inside to ensure the glazing beads cannot be removed by a potential intruder who could then remove the glass unit.
You may see the phrases ‘internally beaded’ used to describe aluminum windows and doors. This is what they are referring to.
Lead times
Bonded glass or bonded glass systems will have a slightly longer lead time to typical beaded systems. This is due to a few different factors.
One factor is that when bonding glass you must use a silicone sealed glass unit. These units have a longer lead time from manufacturers as they are more specialist units, the silicone seal takes longer to apply and cure.
When the glass unit is made you have to allow time for the glass unit to be bonded to the frame.
With beaded glazing there are shorter lead times as there is no curing necessary. The materials used for bonded glazing are easier to source which also contributes to shorter lead times.
Glass Replacement
Due to the strength of a bonded glass unit it is impossible to remove a piece of glass from the frame without damaging one or the other. If a unit of bonded glass needs to be replaced it is likely that the frame will also need replacing too.
For example, if you needed to replace a unit of glass within one of our Sieger aluminium slim sliding doors we would also need to replace part of the outer frame of the siding unit (not the entire outer frame).
Another factor to consider in your glass replacement plan is that bonded systems tend to be large units of glass. That means specialist glass lifting equipment may be required to remove and replace glass if it is classed as overweight.
Beaded systems tend to be easier to replace. First, because beaded systems tend to use smaller, lighter pieces of glass so replacements can be done by hand.
Another reason is that, with beaded glazing the glazing beads can be removed from inside the building, the glass removed, replaced and the beads put back with minimal disruption.
Silicone as a bonding agent
Structurally bonded glazing uses silicone as the bonding agent. Using silicone has many benefits, it can withstand more extreme temperatures and is more water resistant than many other sealants.
Even in products where the glass is not bonded to the frame and instead has a bead locking in in place, if the unit is double or triple glazed there needs to be something round the edge of the glass to join the pieces together to seal and weatherproof the unit.
Some companies use butyl or hot wax to seal the edge of the glass and prevent water and condensation getting in between the glass panes however both come with issues.
Neither butyl or hot wax sealants have the same level of water resistance or thermal performance as silicone. These materials can also become unstable at certain temperatures
At Sieger even on our beaded glazing silicone is used to seal the edge of the double and triple glazed units.
We have a range of both types of glazing products, and our team can help you figure out which is best suited to your project.
Sieger’s Slim Sliding Doors are bonded as are the Sieger Lux and Super Lux Bifolds, these products are known for their slim sightlines. Siegers 120 Bifold Door and the Sieger Legacy Systems are beaded and tend to be used in more traditional designs.
When it comes to the Sieger Thermally Broken Rooflight, if multiple panes are being used next to each other structural silicone bonding will be used to join the panes together.
For more information contact our technical team or book a showroom visit where you can discuss your project in person and see the Sieger systems.
To talk to the team, call 01494 722 882 or email [email protected]
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