We moved into a new building a few days ago. And immediately the huge gap between the bottom edge of the door and the floor caught our eye. We pointed this out when we handed over the building, but always responded that it must be due to the internal ventilation system or something. Measured today. There is a 25mm gap between the bottom edge of the door and the tile! Could this be normal? Is the construction company's argument correct? It looks stupid and dragging. That's not the whole point of a new building that is considered extremely energy efficient.
For the bottom air gap between the bottom edge of the door leaf and the top surface of the finished floor, the mathematical nominal size is 7 mm. Taking into account allowable tolerances, the bottom air gap can range from a minimum of 1.0 mm to a maximum of 11.5 mm, although these extreme dimensions are unacceptable in practice.
Is that the door to the bathroom/toilet? If so, it's okay for the "steam" to come out into the bathroom. There was a time when they built ventilation grills into doors.
For other doors 1 – 1.5 cm is fine
We usually have it handled differently for the necessary circulation for residential ventilation. The maximum gap at the bottom of the door is 3-5mm, the door frame is specially milled at the factory on both sides for this purpose, not visible at the top .
A few millimeters is fine, but 2.5 cm is definitely not acceptable either. It looks terrible.
Our ventilation system manufacturer provided us with a calculation that shows how big the appropriate gap under the door needs to be to guarantee that the ventilation system will work smoothly. In the living room and bedroom, we have to leave a gap of about 5 mm high under the door, and in the bathroom it was 1.2 cm. And even this 1.2 cm I consider too big and would not fit me, so now we solve it with a small gap under the door and additionally using milling in the door frame.
I consider a maximum of 5mm normal.
What you got delivered is definitely not okay, and even with the venting system it's too much.
I mentioned this to the carpenter because we are also getting a ventilation system. Said about 5-7mm is about right, no more than that.