ᐅ Bathroom ventilation dripping despite pipe insulation

Hello everyone,

We already had the problem in March that condensate was dripping from the bathroom exhaust air duct. The pipe passes through the vapor barrier layer and goes through the uninsulated roof to the outside. It has a bend and includes a "condensate trap" – whether this makes sense or not is unclear.
Last time, the trap was full. The solution was to empty it and, of course, properly insulate the uninsulated pipe on all sides (which the carpenter did).
Now the problem is happening again. From a physical point of view, I would say just wrap more mineral wool around the pipe – or are there better solutions?
The building inspector is hopefully coming by tomorrow to have a look.

Thanks for your tips.

Yes, the exhaust air probably cools down too quickly, causing condensation to form. So, more insulation is needed, and above all, airtightness... the length of the duct will likely be another issue as well.

Thank you.
So, should I try once more? That’s frustrating.

There are calculators and formulas for this kind of thing. Actually, the ventilation specialist should have told you that this won’t work and that more insulation is needed, or a different approach.

The bathroom exhaust was a joint effort by the plumber, general contractor, and carpenter... fortunately, it is still fully accessible.
However, I think the design is now quite difficult to change...
By airtight, do you mean the duct must be sealed airtight on the room side? It almost certainly is not.

BeHaElJa schrieb:
Bathroom exhaust

Pure curiosity: Could you briefly describe or sketch the airflow path and where exactly it is dripping?