110mm hole cutting in 220mm floor beam

[jon]

I'm going to make a hole for the drainage ventilation in a 220mm beam. Spontaneously, it feels like a 110mm hole would reduce the load-bearing capacity, but according to Träguiden, it's okay. Have I misunderstood something or is it just okay to go ahead and drill?

 

[anaitis]

It completely depends on where in the beam's longitudinal direction and how it is supported - continuous over the middle support (3-support beam) or with only one span. Additionally, the length is a factor.

 

[jon]

Oh, there wasn't much I understood from that...
It's barely 2 meters long. What do you mean by middle support, compartment, etc.?

 

[anaitis]

With that length, you can easily place the hole anywhere you want along the beam's longitudinal direction. Try to position it centrally in the vertical direction.

 

[jon]

Thank you for the quick and straightforward answer!

 

[Stefan N]

Can't you lower the dimension? 110 is quite a strong air vent.

 

[jon]

It would have been convenient, but I don't want to go up a dimension when I splice onto the cast iron pipe.

 

[JOW]

Just as a tip then...
I go with 75mm for the exhaust/intake ventilation, and increase to 110mm immediately after passing the vapor barrier towards the cold attic.

 

[jon]

I understand that it doesn't need to be 110 for the ventilation, but it feels completely wrong to change the dimension in the wrong direction. Imagine if someone ever decides to install a toilet on the roof