Exterior glass walls and windows

Glazing what might once have been a solid wall is now a possibility, thanks to advances in technology, but getting the design right at the outset is vital.

TODO alt text

ABOVE: Glazing that spans two floors of the hallway of this house fills the space with light, while the glass balustrade allows a clear view of the garden beyond. Roofs from £950 per m², Sunparadise.

Glazing what might once have been a solid wall is now a possibility, thanks to advances in technology, but getting the design right at the outset is vital.

Where should it be used?

You are much more likely to be allowed to use generous amounts of glazing at the back of your house than at the front – and this makes sense to live with, since the view of a garden is much more desirable than that of the street. If your budget can’t stretch to a single vast sheet of glass, smaller panes can be joined with silicone to create a similar but more affordable option.

What are the design issues?

‘For a solid glazed wall, careful thinking should go into the glass and frame and how these connect into a wall or a piece of cladding,’ says Robert Dye, founder of Robert Dye Architects. ‘Integrating these features is difficult, which is where an architect will come into their own in getting this right. This is true of glazed walls and large windows, but particularly of glass doors, too. How they fit with the roof above and the threshold below is vitally important to the success of the design as a whole. A good architect will put a lot of effort into making these complex transitions look effortless.

‘What also drives the design will be whether or not the glass has exposure to the sun. If so, we might recess it or create an overhanging roof. More light in a building is good, but glazing brings heat loss or, more likely, heat gain. We usually put in something like a trench heater that will kill the draught that comes off a glazed door.’

David Cummings, managing director of CSGS, recommends heated glass for glazed walls. ‘Heated glass distributes heat evenly; the outer pane reflects the radiant heat to the inside and the radiant cold to the outside. It is particularly effective in houses with high ceilings or those that are open to the rafters. The starting costs of heated glass units are approximately £780 per square metre. However, the costs of fitting such technology would be offset by the energy savings in the long run.’

Which frame materials to choose?

‘In terms of comfort inside, to get the benefit of a fantastic glazed wall, you have to work hard to stop draughts,’ explains Robert Dye. ‘I’ve found timber more problematic than steel or aluminium – it shrinks, expands and twists over time, so wooden windows need to be thought through very clearly and maintenance is an important issue. We never specify uPVC frames, because we don’t think their manufacture is sustainable, plus I’ve found that the material discolours and isn’t suitable for painting. Powder-coated aluminium is good from a design point of view but isn’t as strong as steel, so it needs to be cleverly engineered if it is to remain thin. Aluminium frames tend to offer good sound insulation, if that’s what you’re looking for.

‘It’s worth bearing in mind that the frame assembly – not the glass – is the key to the success of the build. Both frame and glass will come from the frame assembler. We often use Fineline, which offers narrow frame sections, ideal for decreased interruptions to sightlines.’

All prices and stockists correct at time of publishing.