Guide
How to measure for a door flood barrier.
Measure the clear opening in millimetres — the gap water passes through, not the door leaf.
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What 'clear opening' means
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Step by step
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- Measure the width at the base of the opening.
- Measure again at mid-height and top.
- Use the smallest figure, in millimetres.
- Note the threshold and reveal condition.
Common mistakes
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Photo examples
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