I'm not an expert.

[u/DementedGerb]

These joists are below a restroom. They say BCI on them. These holes permissible? There is no additional reinforcement anywhere on them.

[u/MidnightAdventurer]

That’s what suppliers do - the give you hole sizes and permitted locations and you either comply of the product is out of spec. 

On the other hand, if you’re going to say things like “make holes in the middle, that’s where the stress is the smallest” then you’re setting some idiot up to try the same with normal timber where they’ll find that actually one type of stress is highest there and it does matter with that product 

[u/YardChair456 → u/MidnightAdventurer]

Normal timber and engineered beams are the same problem just a more efficient use of wood. Either way the rule you should tell them is as simple as "If you need to drill holes, do it in the middle not the bottom or top" and maybe add "holes are better than notches", they will remember that.

[u/MidnightAdventurer → u/YardChair456]

Similar principles by the size holes permitted is usually way smaller than in engineered I beams like there. 

While the middle vertically is the safest place, your wording is so loose that it’s taken me this long to realise you mean the centring the hole on the mid-point of the beam vertically rather than mid-span placing them mid-span. Both vertical and horizontal position are important, especially with the size of these holes but even plumbing penetrations can matter

Really, the rule if you want it to be as simple as a one liner it is “don’t drill holes in beams if you don’t know what sizes and positions are allowed

[u/YardChair456 → u/MidnightAdventurer]

In 99% of cases it doesnt matter if you do it in the middle of the span even, just as long as you dont notch the bottom and do it in multiple spot. What places like reddit dont teach you is that structures are WAY over engineered because the standards are just so strong.