The size of opening is large so I expect that you will need to accommodate some structural beam and possibly column support to carry the roof over the windows. Depending on window type, you may also need the new structure to carry the windows, particularly if they are sliding or bi-folding types – which can be top-hung.

At 8m, the new steelwork required is likely to be quite substantial in depth so you may want to consider splitting up the span into smaller sections (i.e. columns every 2m to 3m so the beam spans a shorter distance). The columns are relatively slender at around 10cm. The beam can be shallower and this works well as part of the overall glazed screen.

Because it’s an existing building going from commercial to residential use; Building Regulations will require upgrades to the thermal envelope so do bear this in mind, especially when adding so much glass. Glass, whether double or triple glazed, is a relatively poor performer when it comes to retaining heat. With so much glazing, without including other thermal improvements, you may find this very expensive to heat.

I would suggest looking at introducing as much insulation where practical to the floor, walls and roof. If you wanted to gain better performance still; look at improving air-tightness by using an internal membrane. If you do this also consider that you will probably need a ventilation system to control airflow. The end result will be a greater performing building that should be cheaper to run in the long term.

Lastly, consider orientation of the glass for privacy and potential overheating issues. I guess that the large amount of glazing is looking onto a private garden? If the windows happen to face south, you may need some external shading device or internal blinds to minimise heat gain and glare into the building in the height of summer.

Opinder Liddar (Build It expert)