(TECH, 3.5.7.1)

• "rough opening" term not used;
  • When measuring to the actual frame is not possible:
    • Measure the glazing and add 76 mm (3 in.) for fixed windows or 152 mm (6 in.) for operable windows, to the glazing's width and height to approximate the frame size.

• Window size based on manufactured frame size
• Where single or multiple windows have no structural vertical separations between them, assess the windows as one window system.
• A door system may consist of one or more doors and may include glazing surfaces such as door lights, side lights and transoms. Windows installed within a door system are considered part of that door system.