Exhaust hood with only 100 HT pipe installed for exhaust air

Hello,

I just had to realize with alarm that currently the extractor hoods for exhaust air require a diameter of 125mm to 150mm. However, in October, the roof outlets were installed with zinc extractor pipes of 100mm each. One for the kitchen and one for a new bathroom.

As I now find out, this is fatal. Sufficient for the bathroom, but unfortunately not for the kitchen. Additionally, the roofer's recommendation was to install an S-bend so that no condensate leaks out. The pipe leads through a flat (cold) roof.

Unfortunately, the work has already progressed far since October, so the ceiling is already closed. But that should not prevent me from opening the ceiling again.

The only question is, who pays for the necessary work. The offer mentioned "installation of new extractor pipes." The roofer should actually know what the standard is in the kitchen and bathroom. I did not... until now.

PS: Or is it enough to use a 150mm HT pipe + condensate trap from the extractor hood to the 100mm extractor pipe, after all, there is a narrowing again, albeit shortly before the outlet, but still!?

Regards
Obsthaendler

I have meanwhile spoken with two independent roofing companies. Both had installed a 100mm zinc vent pipe and said sometimes also 125 and 150 almost never. What is correct now?

mM: "correct" can only be what is prescribed by the manufacturer of the hood. The fact that this is almost never adhered to does not mean that it should not be adhered to.