A glass box extension is a complex amalgamation of various elements of structural glass, being brought together to create a glass box that can be used as a window box seat, extension or conservatory.
Roof glazing, glass walls and glass doors can all be used to create an extension or conservatory made purely of glass for a striking appearance and maximum light ingress.
With these highly glazed constructions thermal performance and solar gain can both be issues to address.
Ensure that all glass used is a double glazed unit at minimum with heat reflecting low e coatings to reflect radiant heat back inside the space. Triple glazing will provide a higher thermally performance whilst heated glass will turn your glass walls into a radiant heat source for a wonderfully comfortable space.
As there are generally no frames in a glass box extension to hold or support any internal shading so privacy and solar protection are elements of the glass design that will need to be considered at an early stage.
If there are close overlooking properties and privacy is required consider using a sandblasted unit or a translucent coloured interlayer within the glass. This can be used on the roof or sides of the glass box extension to allow light to enter the space without neighbours being able to see in.
A solar control coating to the glass is usually advised to reduce the amount of solar radiation able to enter the glass space.
When considering the access doors required to the glass extension think about what is most important to you; minimal frames or large opening elevations? Sliding doors will afford you the slimmest framing whilst bi folding or hinged patio doors will have a thicker frame but allow you to open up a larger area of the extension.