ᐅ Controlled residential ventilation air duct from supply to exhaust area: examples and sound insulation?

Hello, as the title suggests, I would like to know how, in your houses with centralized mechanical ventilation with heat recovery, the air is directed from supply air rooms to exhaust air rooms.
- Under the door? With what gap size?
- Over the door frame?
- Special transfer grilles?

How do you find the sound insulation (possibly with a note on the construction method or the general sound insulation level of the house)? Is there any draft? Is there light passing through in case of door gaps?

What else would be important?

We have a small gap under the doors (approximately 8-10mm (0.3-0.4 inches)). Since doors usually have a small gap at the bottom anyway, it is hardly noticeable. Noise is not an issue – we also chose solid wood doors. The same applies to drafts. A slight draft can be felt at the gap, but only there.

I am doing it over the door frames – 8-10mm (approximately 0.3-0.4 inches) at the door threshold is almost too narrow for proper air exchange, which you can also feel as a draft.

Above all, such a gap is not ideal in terms of light and sound insulation...

nordanney schrieb:
We have a small gap under the doors (about 8-10mm (0.3-0.4 inches)). Since doors usually have a small gap at the bottom anyway, it’s barely noticeable. Sound isn’t an issue either—we chose solid wood doors. The same goes for drafts. You can slightly feel the draft at the gap, but only there.

In my rental apartment with parquet flooring but without a mechanical ventilation system, I have a gap of about 11mm (0.4 inches) under the door.

Is your gap size the result of a design calculation? Were the door leaves shortened accordingly? Are all doors/gaps the same? What airflow rates are intended to be transmitted?

By the way, sound and light insulation with this 11mm (0.4 inches) gap is not as bad as I expected.

Lexmaul79 schrieb:
I do it via the door frames

Did that lead to an unexpected additional cost? What needed to be considered in the planning (rough opening size somewhat larger)?

The frames are only foam-filled at specific points; I might sand down a bit of the wall. This creates a continuous surface around the gap, which is significantly larger than the gap at the bottom. As a result, there is no draft.

No additional cost, no increase in the rough construction dimension.

The gap under the door was specified that way (by the ventilation specialist). Calling the airflow under the door a draft would be an exaggeration. Let’s just say you can notice a slight air movement.
We had the doors made to the exact height by the carpenter, so they didn’t need to be trimmed. Since the frame sits flush against the wall, installing ventilation above it wasn’t an option for us. A gap there would also look odd, as our doors are all fully flush-fitting – giving the wall a seamless, solid appearance.