Windows

The sizes of openings for windows changed as the materials and styles of casements changed. Smaller, squarer windows are a reasonable indication of age, as windows generally evolved to become larger and more elongated. See Defects, repairs and changes over time.

The repair of early glass is specialised work, and the care needed to undertake this type of work should not be underestimated in financial or project planning terms. Breakage is likely and the value of the glass may mean that frames have to be sacrificed.

The Georgian period of house construction is dominated by vertical sliding sashes. These are very effective mechanisms for ventilation and provide one of the main style characteristics of the iconic Georgian house. Although a very robust design, they are prone to decay through age or poor maintenance. See Sash windows.

Crittall metal-framed windows became the most popular form of window. They were particularly used to create swept curves on houses and flats and were often referred to as 'suntrap windows'. See Defects in metal windows.

The summary timeline drawing below sets out the types of window types most likely to be encountered, and the approximate date at which they appear. Windows are the most likely element to be changed in a house, so it cannot be stated categorically that one particular type of window defines the age of the property. Other features should also be observed.