What happens when that joist is located directly under the drain for the toilet? The first and most common approach is to cut, notch or in some way alter the joist to accommodate the drain piping. With dimensional framing a simple repair could be to “sister” on a section of scrap joist material to the appropriate size to provide the needed support. However, when this scenario presents itself with an engineered framing member the repair is not so straight forward. Any alteration to an engineered framing member must be designed by an engineer. Strict guidelines must be followed when altering the framing otherwise the integrity of the member is compromised. And NEVER are you allowed to cut or notch the top and/or bottom flanges. I find this all the time and it always makes me shake my head. Most engineered framing manufacturers have repair designs on file which can be implemented by a qualified and licensed contractor. But these steps can easily be avoided during construction if the various subs on-site would communicate better. The picture shows a relatively mild alteration to the “I” joist; I’ve seen much worse. Regardless, this type of construction defect continues to irk me every time I see it because it is so easily avoidable…it also helps to reinforce the need for a quality inspection.