Controlled residential ventilation: Is an air gap under the doors required?

Hello everyone,

we are installing a central controlled residential ventilation system. I have heard several times that the interior doors need to be shortened by about 1 cm during installation afterwards to allow sufficient air circulation.

Is that true? And if they are shortened, then there is an "open" edge at the bottom without any coating or edge banding, is that not a problem?

How is it with you?

The doors must be ordered and installed to fit, then you won’t have to shorten them afterwards. It has worked without any problems with all our doors.

Doesn't it cost a lot extra if the doors are then ordered to fit?

Nope, the price was the same. But even when installing standard doors, there should actually be enough space. We have our (solid wood) doors from the carpenter.

Have a look here, almost the same topic. In post #13 you can see how we solved it.

Allow me a question here. Does anyone of you from the company Renson know the Invisido system and has installed it? The background of my question is that an acquaintance is retrofitting controlled residential ventilation as part of renovation measures, which apparently requires shortening doors. As far as I have read, shortening the doors by about 8mm would probably be necessary. He does not particularly like that for aesthetic reasons (but will accept it if there is no other way). An alternative would be soundproof door grilles, which, as it seems to me, would also not look very appealing. Hence the question about the above-mentioned system.