How much notching is too much before you say something?

I'd say something, and I've got a reason that still stings. My sister bought a spec house about six years ago and I walked through with her before closing. I saw a duct run that had been shoved through a couple of engineered joists near the bearing ends and I figured the county inspector would've caught anything real, so I kept my mouth shut. Two winters later one of those joists cracked and the floor above it got bouncy enough that you could feel it walking across the living room. Turned out engineered lumber can't just be drilled anywhere the way regular dimensional lumber can, and the repair involved a contractor sistering boards on both sides. Not cheap, and the builder had long since stopped returning calls. So now my rule is document first, talk second. Take photos from a few angles with something in the frame for scale, then mention it to your friend casually, like hey, this looked off to me, might be nothing. If he's still early in the build, the builder can fix it for the cost of a conversation. Once drywall goes up it becomes a much bigger arguement. As for hiring someone, if your friend brushes you off, a one-time inspection from an independent inspector costs a few hundred bucks and buys real peace of mind. I wouldn't frame it as tattling, I'd frame it as cheap insurance on the biggest purchase he'll ever make.

I disagree with the idea of imediately confronting the contractor. When I saw a rough-in issue on a house my uncle was building, I didn't go straight to calling the crew out. The problem wasn't a hole in a joist, but rather that they were using inadequate sealant around the penetrations for the plumbing lines going through the sill plate area. The caulk they used looked like cheap silicone, not the proper polyurethane type needed for moisture resistance. It looked sloppy, sure, but immediately calling the GC would just turn it into an argument, and I didn't have all the answers about the building code for that specific sealant requirement. Instead, I found the local inspector's manual online and double checked the manufacturer specs for the grade of sill plate they had. I realized that while the application was poor, the material itself met the minimum requirements if the installer used the correct tool to apply it. My approach was to document everything with photos and then ask my uncle's trusted project manager to just point out the specific technical specification I was worried about. That way, the issue was framed as a technical question, not an accusation of bad work. It allowed them to fix it quietly without escalating the situation into a dispute over competence. It's ussually smarter to gather facts first.

Agree with the photos-first approach here. When my cousin's place was getting finished I snapped pics of a notched joist in the basement and sent them to him before saying anything to the builder. Turns out showing the picture at the walkthrough got the issue fixed the same week, no argument needed, because it was still all open framing and easy to touch up. Waiting untill after drywall would have made it a whole fight. One thing I'd add, go back and shoot the same spot again in a day or two, sometimes crews come through and clean up or patch stuff between inspections and you want the current state on record.

When my own place was being framed I had a similar moment with an hvac guy who bored way oversize holes for his lines. What saved me was just measuring. I pulled out a tape and jotted down the hole size and where it sat along the span, then looked up the hole rules on the lumber manufacturer's site and sent it to the builder. Having actual measurements in front of him meant the crew came back and filled the bad holes with blocking, no argument at all. So if your friend does say something, tell him to go in with numbers, not just a feeling that it looks wrong.

I don't know any of the rules myself, but when my neighbor's place was going up I'd stop by sometimes and the city inspector guy was in and out in like ten minutes. Made me realize those quick checkups prolly miss a lot of small stuff. So yeah, I'd mention it to the friend even if it turns out fine. My question is, how do you even know if the hole is too big? Is there some rule about how close it can be to the edge of the board, or does that depend on the type of wood?

I think the fundamental issue isn't just the size of the bore, which is certainly a concern, but rather where the joist is situated within the load path. If that joist is carrying a primary structural load, even a minor compromise can affect the localized stress distribution, especally if the wood material is significantly weakened at the point of penetration. I once saw a case where drilling too close to a connection point meant the remaining wood couldn't effectively transfer the load into the adjacent wall plate, leading to premature deflection years later. It makes me wonder if the crew was aware of the specific grading or the material specifications for that particlar joist. What usually happens when a hole is drilled adjacent to a fastener location, does that require a specific kind of reinforcement?

Update: I took the photos-first route and sent them to my buddy without saying much, just asked if he'd want them for the walkthrough. He actually used them and the builder's coming back to look at it. Still stuck on the measuring part though. For those who checked hole placement against the manufacturer's rules, where do you even find the limits for a regular dimensional joist? Engineering tables only, or is there a simpler spot to look?