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

WildThing schrieb:
Hello everyone,

we are building with a centralized mechanical ventilation system with heat recovery. I have often heard that interior doors need to be shortened by about 1 cm (0.4 inches) after installation to allow adequate air circulation.

Is that true? And if they are shortened, there will be an "open" edge at the bottom without any coating or edge banding—is that not an issue?

How is it in your experience?

In our case, the doors were also custom ordered to size. And yes: with mechanical ventilation systems, there must be a gap—our construction plans also show the directions of air flow. The architect explained this to us as well.

ypg schrieb:
And yes: with controlled residential ventilation, there must be a gap

No, it is not necessary. Air transfer can be ensured by
- a gap under the door
- a gap at the top between the frame and the wall
- drop seals with an air transfer opening
- wall vent
There may be other options as well. If you are interested, I can share a link to a site that has been explaining this well for 10 years.

If it is a door gap, it does not have to be "we have always done it this way" 1 to 2 cm (0.4 to 0.8 inches); rather, the gap height depends on the airflow rate, the desired pressure loss, and the door width.

(Air transfer openings are also a topic that seems to be completely new for my builder ops

Neige schrieb:
Company Renson’s Invisido system

Interesting, I didn’t know that. Are you familiar with Mine drop seals from Planet?

No, I’m not familiar with that, but I’ll take a look. Thanks.
Edit: I know about recesses, but not from Planet.

Sent from my mobile device

Thanks @One00 for your link. So, you have the “overflow opening” above the doors. Did you install that yourselves? And in that area, you don’t have any spray foam or anything, it’s really open? How satisfied are you with your solution?

However, this topic doesn’t seem to be very well known among door manufacturers or installers. So far, no one has asked us if we have a mechanical ventilation system with heat recovery, and when we mentioned it ourselves to one, they didn’t know if or how much attention was needed for that.

In our execution plan, there is no information about airflow directions or special door dimensions... (Although the airflow directions are clear, since we generally have supply or exhaust depending on the room.)

WildThing schrieb:
Thanks @One00 Do you also have no expanding foam or anything in that area, so it’s really open?

The door frames are only foam insulated at specific points. By the way, I think this solution is quite good. The recesses are done quickly.

Sent from my mobile device

We will slightly adjust the door frame forwards or backwards to make the shadow gap a bit larger. It will then be insulated only in small areas so that the overflow opening between the door and the wall remains.

Advantage: No light, no sound – and definitely no large gap between the door leaf and the floor, which in my opinion is unacceptable...