How to Measure a Composite Front Door
These guidelines are designed to help you accurately measure for a new external composite front door and frame. If you are unsure at any stage, we strongly recommend contacting a professional door installer to carry out a full site survey.
General Measuring Guidelines
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Always measure from the outside
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Measure the brickwork opening, not the existing door or frame
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Take at least three measurements in each direction
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Use the smallest measurement
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Deduct 10mm from both height and width to allow a 5mm fitting tolerance all round
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This allowance ensures the new frame can be installed plumb and square, with packers and silicone used to secure and seal the frame
Please note: We do not apply fitting tolerances to the sizes you submit.
Important Reminders
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Do not measure the existing door or frame
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Measurements must include the full frame, cill, and any frame extenders
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All dimensions must be supplied in millimetres (mm)
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All door designs are viewed externally
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Always double-check measurements before ordering
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The finished frame size must be smaller than the brick opening
Trade Doors Online cannot accept responsibility for incorrect measurements. If in doubt, always use a qualified fitter, joiner, or builder.
Measuring a Double-Glazed Door and Frame
Width
Measure brick to brick at: Top, Middle, Bottom
Use the smallest measurement, then deduct 10mm.
Height
Measure brick to brick at: Left, Centre, Right
Use the smallest measurement, then deduct 10mm.
Measuring a Double-Glazed Door With Top Light
Side Panels
Measure total width brick to brick (top, middle, bottom), Deduct 10mm
Measure side panel width from the centre of the frame mullion to the outer edge of the side panel frame
Top Lights
The height should be measured brick to brick at three points – left, middle and right of the opening. The smallest of these measurements is taken as the height. Always deduct 10mm from the final height.
