Ventilation in windowless rooms

When is the blower-door test performed?

Sorry, it should of course be door. Word finding greets you ;)

Why? A small bathroom without a window should have a fan, shouldn't it?

Good evening,


Who sells/installs something like that?

Rhenish greetings

Sounds strange...

If it really stays that way, in my opinion, you can forget the Blower Door test.

In our Blower Door test, there was exactly one opening in the building envelope, and that was the flue pipe connection on the chimney on the ground floor, because our stove had not yet been installed.

That must be somewhat similar to your "ventilation through the roof" in your interior rooms.

However, our flue pipe connection was very thoroughly sealed so that no drafts could occur.