The idea of frameless glass derives from some of the great Modernist architects, especially Mies van der Rohe and his ideas that a building should be rooted in its landscape. New techniques in the 1920s and 1930s of using glass and steel meant that these uninterrupted visual spaces, as some architects call them, could be created.
Walls of glass like this have been relatively common in high specification houses in California since the 1950s, and in recent years the technique has been creeping into contemporary domestic buildings in the UK.
What can you use Frameless Glazing for?
Frameless glazing is most frequently used to offer unobstructed views of the home’s surroundings. As one architect put it, the idea is that the frame does not get in the way of the views so the occupants can live as part of the landscape rather than locked away in a house with small windows and entirely cocooned from the world outside.
Therefore this style demands as few glazing bars as possible and fixings are kept to a minimum to preserve the integrity of the view. Today many self builders like to use variants of this technique because it is a good means of allowing optimum light into a house.
Other uses inside the home include frameless glass shower panels, glazed balustrades on balconies and stairwells, and frameless doors. Whatever its application, frameless glass has to be strong enough to hold its own as a wall, door or screen and be safe from fracture.
How Safe is Frameless Glass?
Toughened glass and laminated glass are used to produce frameless glazing that is safe for most applications.
Toughened or tempered glass is made by heat-treating float glass in order to change its physical characteristics. This makes it much stronger than normal glass and also means it breaks more safely. Instead of shattering into sharp splinters, toughened glass crumbles into granular chunks, which is why it is used for car windows.
The main disadvantage of toughened glass is that it has to be cut to size and drilled before toughening takes place.
Laminated glass is made from sheets of glass sandwiched together. These are separated by a thin film of material such as polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA). If it cracks, the film holds it together.
How Energy Efficient is Frameless Glazing?
Part L of the Building Regulations demands certain U values for walls, floors, roofs and windows. This is to ensure the overall fabric of the building is efficient, reducing heat loss and thus saving energy. Windows must achieve a U value of 1.4W/m²K or lower (the lower the better).
Modern frameless glass tends to be manufactured to these standards, with some surpassing it and offering added thermal efficiency. It is also worth noting that where glazing is used for a roof or wall, it does not have to meet the U values for these elements as specified in Part L — it is sufficient if it meets the U values for windows, rooflights and doors.
Frameless glazing is not to be confused with structural glazing, in which the glass actually holds up the building. Structural glass works by using toughened glass that has been laminated, or set in layers. Sometimes these layers can be four or five layers deep. The resulting glass can be double or triple glazed.
The structural requirements are defined by the Building Regulations. The actual strength of the glass is determined by the size and thickness of the sheet and, consequently, the cost of using structural glass varies enormously depending on how large the spans involved are.
How Much Does Structural Glazing Cost?
Structural glass balustrades (which require a horizontal load set at 0.74k/Nm to stop breaking or bending from a sideways force), work out at around £700/m. This means a stairwell solution could cost more than £2,000.
An all-glass rooflight costs from £1,200/m² for a fixed light. This could be up to three times as much if you want them to open or slide. You can also get glass which is strong enough to walk on (to use for a roof terrace or between floors), which can be ‘fritted’ with small ceramic pieces to make them less slippery.
Sliding Door Systems
If you want an opening glass door system with the minimum of framing, a sliding door system is the best solution. The glass doors are supported continuously along the base, designed to glide past each other, rather than folding into a concertina.
IQ Glass provides a range of slim-framed systems with multiple opening configurations available. With its double-glazed system you can achieve a tiny 21mm vertical profile between frames; for better thermal performance, the triple-glazed systems have a minimal 26mm vertical profile. Individual leaves can measure up to 12m2 in size — in other words, as much as 5m long. The Hedgehog Aluminium Sieger 30 system has a 30mm vertical sightline and is a more cost-effective option, albeit with a few more restrictions on sizes and configurations.
Both systems can supply glass doors designed to open on to a corner. Here the doors are installed to meet at a corner connection and both doors can be opened away from this point, leaving no post at the junction. Another popular option for those wanting a complete break between inside and out is to use external pocket doors which slide away into a recess in the side wall. Obviously the more door panels that are designed to slide into the pocket, the wider the pocket— and the wall— have to be.
Overheating and Privacy Solutions
There are other clever things that glass technology can now supply with a frameless glazing system. If overheating is a potential problem, as it can be with some rooflights or with south-facing façades, you can add an electric shading capability to the glass (at around an added £1,600/m2).
Privacy glass (which puts an electrical charge through it to change translucent glass to obscure) and heated glass are also options, albeit at similar price points.
While these sorts of costs will only appeal to high-end projects, the fact that they are becoming available at the residential level shows just how much glazing techniques are progressing. And although apparently expensive, they can solve a range of problems that can be even more expensive to achieve by other means.
Architectural Glazing Specialists
Self builders wanting to incorporate frameless glass within their structure are probably best advised to speak to an architectural glazing company. Their architect doesn’t have to be familiar with structural glazing or specific systems, as the specialists will design and detail the structural glass connection, building connection and glass specification themselves.
There are an increasing number of architectural glazing specialists and more and more of them are moving their attentions onto the residential market as the popularity of the product continues to grow.
It can be a difficult area to research, but one facility well worth getting an appointment to visit is the IQ Glass Courtyard Showroom in Amersham, Buckinghamshire. The company has set up a demonstration area where you can get hands on with everything from privacy glass to pocket doors, plus there are many other products likely to be of interest to self builders planning on using frameless glass in their projects.