A Guide to choosing windows for your extension.

Windows are a crucial element of any building work. You need to take care in deciding which type of window will suit your house or extension. The decision-making process should begin with understanding your home and whether any new extension should match or set itself apart. It is usually more impressive to set any new building work apart from the existing building but not just for its own sake. The language of architecture is personal. At G.A.Architects, we aim to make buildings that are respectful of the existing structure (i.e. contextual) whilst making it contemporary and of its time. This method often situates the building work clearly within time (i.e. history). Ultimately the design decisions will be made by you, the client, who may have other priorities or preferences.   

There are a few different choices of window material (shown below); however, there are also the choices related to the thermal efficiency of the window and whether it should be openable; swing open, top hung, side hung or sliding. The size and position of the window are also crucial.

  • UPVC
  • Timber
  • Aluminium
  • Composite
  • Steel

The two keys parameters that will guide the window’s positioning and size will be to what extent you want to harness the view that the window will frame and how much natural daylight you want to allow into the room.

Too much natural daylight is as bad as too little daylight, so this decision is essential.  

If the total area of all new glazing exceeds 10% of the new floor area, an SAP calculation is required to show that the building does not exceed the minimum heat loss standard.

If the view through the window is significant, then the window frame should be minimised so that it is not interrupted by unnecessary fenestration.

Fenestration can be a beautiful feature in itself.  Schuco windows and doors are one of the best quality aluminium frame suppliers you will find, and a lower budget option is Kloeber.  Crittall windows (steel) have nicely proportioned fenestration and have internal and external options.  Velfac is another excellent window and external door supplier that make aluminium/timber composite windows.  And Rehau is a good supplier of uPVC windows and doors.

There are other detailed design possibilities other than the position of the window within the wall. The window can project beyond the wall to allow a window seat within the wall depth. This type of window is called an Oriol window. An external window seat or planter could be created by simply setting the window inside or making an oriel window. The depth of the exterior wall also plays an important role here.

There are further options related to the glazing itself. Do you want it to be opaque, translucent, transparent, etched or patterned? 

At G. A. Architects we consider the options carefully and with a thorough understanding.

Crittal window
Schuco Aluminium doors