Single-family house without a basement - generate parking space elsewhere

Our ventilation is planned for the attic. I have built the ceiling from the attic as follows.

Gypsum board
15mm OSB
200mm WLG 035 between the collar beams
OSB 22mm

The [Kontrollierte-Wohnraumlüftung] unit is to be installed on the gable wall, with supply and exhaust air at the gables.

Plasterboard
15mm OSB
200mm WLG 035 between the collar beams
OSB 22mm

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You have a wooden beam ceiling, right? We have concrete.