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Generally for all up and over garage doors the order sizes refer to the dimensions of the inside of the fixing sub frame which can be a steel or timber frame. The overall size including the frame is the most important size if installing INBETWEEN the brickwork opening.
For example a 7'0" x 7'0" 'order size' refers to the inside dimensions of the fixing frame and if this was for example a Hormann up and over garage door with a standard 75mm frame this would mean this door would have an overall size including the frame of 2274mm and 2192mm high.
A little bit of confusion may occur with some of the manufacturers as the reference to the imperial size can on fact be the nearest rounded up size. If you take the overall frame dimensions quoted and work the measurements backwards you will find with a Hormann or Garador up and over door the internal frame size will actually be very slightly smaller than the 7'0" reference. It would be 2124mm wide for example (2134mm (7'0") minus the frame width of 75mm each side (150mm) giving 2124mm) but the tolerance for a steel frame around the door panel is always tighter than with a timber frame and as the door ordered with a steel frame is always factory pre fitted you should just focus on the overall frame dimensions. If you are fitting a new up and over door to a timber frame you need to make the internal dimensions of the timber frame the same size as the 'ordering' size and the tolerances for the panel are already included.
Purpose made garage doors with steel sub frames are best ordered with both the overall size required and the internal frame dimensions referred to ensuring everyone is clear what is required.
Different manufacturers also have different sizes for their steel sub frames so please check carefully if the measurements are critical in any way and always bear in mind what 'drive through' sizes you may end up with too.