Wood I-joist drill holes

Floor joists are 12" wood I-joist, I know the manufacturer installs knock-outs for running tubing etc. The plumber drilled 2-1/2" to 3" holes about 1 foot from the carrying beam end and top of beam center. Does anybody know if this creates a structural concern or not?

Sorry, I don’t have any pictures of it.



go to manufactuers web site for the joists, they always show an allowable cut / hole drilling diagram or instructions. Normaly new or larger holes are allowed near the ends or within a few feet of the end.

Sounds fine to me.

I’ve seen them as big as 6". Sounds OK here. That is the great thing about I-joists.

Hi Ron
I think you’ve got it backwards. The maximum shear stress occurs at the ends (support) so the further away from the end, the larger the allowed hole.

Hi. John;

I think Larry’s posted link explains everything here, I believe.


Marcel :slight_smile: :smiley:

Thanks Marcel
Doesn’t the table indicate that the further away from the support, the larger the allowed hole. Am I reading it incorrectly?

Dependant of the series and Manufacturer, that is what it looks like.

Marcel :slight_smile: :slight_smile:

Great thread. Thanks guys.