The foaming of the door frame.
What gap is needed between door, floor and frame : The Foaming Of The Door Frame.
Quote from Article entitled What gap is needed between door, floor and frame:
Unlike interior doors, gaps between a front door and a frame must go with the standards not so much due to the possible expansion of a leaf, but because of the danger of penetration of cold air and extraneous sounds from outside. Such troubles can be avoided by installing a seal, and it is a problem of the manufacturer. If the door is certified according to the standard there is no problem. But in the case where design is not certified, gaps may be of any type and you must glue a seal by your own hands.
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